Parktool  repair manuals
	Are you looking for help on how to perform a repair or maintenance exercise on your bike? You have come to the right place. We have provided an extensive library of repair instructions free for your use right here on our website.

TIRE AND INNER TUBE REPLACEMENT

Typical Tools and Supplies Needed

• Repair stand (optional, makes the work a lot easier)
• Tire levers TL-1, TL-2, TL-5, or body of various take-a-long tools. For professional use, see TL-10.
• Patch Kit such as the GP-2, or VP-1.
• Air pump PFP-2 or PFP-3, hand pump, or air compressor.
• Wrenches for non-quick-release type wheels that use outer axle nuts.

This article will discuss the removal and installation of tires. See also Inner Tube Repair

The wheel must be removed to replace the tube and tire. If possible, begin by mounting bike in stand. If no stand is available, bike should be laid on its left, non-derailleur, and side when the rear wheel is removed. Do not stand bike upright without the rear wheel in place, as this will damage the rear derailleur.

1. Rear wheels, shift derailleur to outermost gear and innermost front chain ring.
2. Release brake quick-release, if any. Typical MTB brakes and road brake quick release mechanisms are shown below.
   
   
   
   
   
   
3. Release wheel quick-release by pulling quick release lever outward. Pull outward on end of quick release skewer lever. If necessary, loosen quick release adjusting nut to clear any tabs at end of fork. For wheels with axle nuts, loosen both nuts outside of dropouts.
4. Front wheels guide wheel down and out of fork. For rear wheels, pull back on rear derailleur to allow cogs to clear chain. Lower wheel, guiding the wheel down through brake pads and forward to clear chain and derailleur. Guide the wheel through the brake pads and out the fork ends.
   
   
   
   

Removing Tire and Tube from Rim

Tires can be tightly fitted to the rim. Use tire levers to pry tire bead up and over rim sidewall. Do not use a screwdriver, knife, or other sharp object, which might damage tire or tube. Fully threaded valve shafts may have a locking nut next to rim. Loosen and remove locking nut before deflating.

1. Deflate tire completely. Even a small amount of air left in the tube can make it more difficult to get the tire off. For best results, press downward on wheel while depressing the valve.
2. Push one bead of tire toward rim center. The tire bead will be pressed tight against rim. Pushing it inwards loosens the bead from the rim. Repeat on other bead.
   
   
   
   
3. Engage one tire lever under bead of tire. Engage second lever 1-2" (25-50mm) from first lever then pull both levers toward spokes to lift bead off rim. Disengage one lever. Move it two inches (5cm) along the rim and engage lever in the bead. Pull lever to lift next section of bead off rim.
   
   
   
   
4. Repeat engaging the lever until the bead loosens. Then slide the lever along the rim under the bead.
   
   
   
   
5. Starting opposite the valve, pull inner tube from tire. Lift valve from valve hole and remove tube from wheel.
6. Remove second bead from rim, which removes tire completely from rim. To fully inspect the tube and tire, it is best to remove both completely.

Other tire lever options:
Some tires remove easier with a thinner and wider lever such the TL-2



Some tire and rim combinations require a very strong steel lever, such as the TL-5

Inspecting the Inner Tube

When servicing a flat tire, always inspect tire and tube carefully to locate the cause of failure. This will help prevent future flats from the same cause.

1. Inflate inner tube if possible. Inflate until tube is twice its normal width.
2. Inspect for air leaks by holding tube close to the sensitive skin of lips or by holding tube near your ear to hear leaks. Move the tube around its circumference. If these steps do not work, submerge tube in water and watch for bubbles at the hole.
3. If you plan to repair the inner tube, use a marking pen to mark hole. Make four marks, one to each side of hole. Do not mark close to hole, as the mark may be sanded off.

   The type of cut or hole in the tube will help determine the cause of the flat. Common causes of tire and tube failures are:

• Cut at valve core, commonly from misalignment of tube in rim or riding with low pressure. Be sure tube is mounted straight in rim and check pressure before rides.
• Leaky valve core, tighten with a valve core tool. More common with Schrader type valves, but also possible on some Presta valves.
• Blow causing a large shredded hole. These are usually not repairable. Check tire and rim as well for damage.
• Hole on inside edge of tube indicates a problem inside the rim, such as from rim strip failure, a protruding spoke or other sharp object inside the rim.
• A long cut or rip may indicate a tire blow out. Typically this is not repairable. Use care when seating tire during installation.
• A single puncture or small hole is commonly from a thorn, wire, or small nail. These may be repairable. Check tire as well for thorn, etc.
• Double slits are commonly from a rim pinch. The tube was pinched between rim and object in road/trail. Increase air pressure or use wider tires.
• V-shaped slits may be from nails or glass.

Inspecting the Tire

It is important to always inspect the tire as well as the inner tube. The cause of the flat, such as a nail or piece of glass may still be embedded in the tire or tread. Inspect both the outside of the rubber tread and the inside of the casing.

1. Inspect outside of tread for protruding nails, pieces of glass, thorns, or other objects. Squeeze any cut to look inside for objects such as slivers of glass.
2. Visually inspect inside of tire casing for nails, glass or debris. Wipe inside of casing with a rag, and then carefully feel inside with fingers.
3. Inspect sidewall for rips, holes, or damaged rubber and casing.
4. Inspect wire or fabric tire bead for damage.

Rim Strip and Rim Cavity

The wheel rim is made with holes between the rim sidewalls for spoke nipples. A rim strip covers the holes or nipples. The rim strip can be made out of different materials such as cloth, rubber, or polyurethane plastic. The strip protects the inner tube from sharp edges in the base of the rim and from spoke ends and nipples that might puncture the tube.

Inspect inside the rim cavity, looking at the rim strip and for any sharp corners or protruding spokes.

The rim strip should be wide enough to cover the bottom of the rim, but not so wide it interferes with the seating of the tire bead. Inspect the rim strip whenever changing a tire or inner tube. Look for tares and rips, and make sure rim strip is centered over the nipple holes. In the image below, the rim holes are exposed, which may cause a flat tire.

Valve Types

There are two common types of valve stems on bicycles, the schrader ("American" type) and the presta ("French" type). The schrader or American-type valve is common on cars and motorcycles. It is also found on many bicycles. The valve stem is approximately 8mm (5/16”) in diameter and has an internal spring plunger to assist in shutting the valve. To deflate the schrader valve tube, it is necessary to stick a small hex wrench or other object into the valve in order to press on the stem and release the air. Upon release of the stem, the stem spring shuts. Schrader compatible pump fittings press on the internal stem with a plunger, allowing the tube to be filled.

The schrader valve core can be removed if necessary. This is rarely required, but a valve can become stuck and cause a slow leak. A loose core can also be the source of a slow leak. A special tool will remove and or tighten the core.

The presta or French-type valve is common on mid and higher priced road bikes and on higher priced MTB bikes. Presta stems are nominally 6mm (1/4”) diameter, thinner than Schrader valves. At the top of the stem is a small locknut, which must be unthreaded before air can enter the tube. To deflate the inner tube, unthread the locknut. Depress the valve stem to deflate. To inflate the tube, unthread the locknut and tap the valve to insure it is not stuck.

Presta valve tubes come with different length valves. The longer valve stems are needed for the deeper aerodynamic rims.

The rim valve hole should match the valve of the tube. It is possible to use the smaller presta valve in a rim intended for the larger Schrader by using an adapter sleeve.

Repairing an Inner Tube

Simply replacing the punctured inner tube with a new tube is always the safest and most reliable procedure. However, it is possible in some cases to repair a small hole in an inner tube. If the hole is quite large, it may not be possible to repair. When in doubt replace the tube.

The GP-2 Super Patch Kit uses pre-glue patches. There is no tube of glue to leak or dry up. The VP-1 uses a vulcanizing fluid to bond the patch to the inner tube.

For inner tube repair, click here

Installing Tire and Tube on Wheel

1. Note directional arrows of tire manufacturer, if any. Directional arrows printed on the sidewalls indicate rotation of wheel. Not all tires have direction orientation.
2. Inflate tube enough for tube to just hold its shape.
3. Install tube inside tire. Install with tube valve adjacent to air pressure recommendations written on tire sidewall.
4. Lower tire and valve into rim valve hole and align valve so it is pointing straight toward hub. A crooked valve can lead to a flat tire later.
5. Install one bead at a time. Work tire bead onto rim with hands. If tire bead will not seat using hand, use tire lever as a last resort. Use caution when using tire levers to avoid pinching inner tube. Engage tire lever using same orientation as removing bead.
   
   
   
   
6. Work tube over rim sidewall and into rim cavity.
7. Install second bead onto rim. Use care if using a tire lever.
8. Inspect both sides of tire for bead seating and for any sign of the inner tube sticking out. Re-install if necessary.
9. Inflate to low pressure and inspect bead again on both sides. Look for small molding line above bead. This line should run consistently above rim.
   
   
   
   
10. Inflate to full pressure and check with pressure gauge. It may be necessary to press downward above the valve in order to engage the pump head. For fully threaded valve shafts, re-install the locking nut, if any. Do not use wrench or pliers to tighten nut. Tighten finger tight.

Installing Wheel on Bike

The wheels must be properly mounted to the bicycle frame. Misalignment can result in problems with shifting and bike handling. If the wheel is not securely mounted in the dropouts, it may come out when the bike is ridden, possibly causing injury to the rider.

Quick release wheels use a hollow hub axle fitted with a shaft, a lever that operates a cam mechanism, and an adjusting nut. The cam puts tension on the shaft and pulls both the cam and the adjusting nut tight against the dropouts. This tension is what holds the wheel securely to the frame. The adjusting nut determines the amount of tension on the quick release lever and cam. Lubricate the cam mechanism if it appears sticky or dry.

The quick release is fitted with two conical shaped springs. The small end of the spring faces the axle, and the large end faces outward. These springs make the wheel easier to install. If one or both springs become twisted or damaged they may be removed. The springs serve no purpose once the wheel is tight on the bike.

Disc Brake Note

Bicycles using disc brakes at the hub need special attention to skewer use. Rim brake systems (Dual Pivot, Linear Pull, Cantilever, Sidepull, etc.) tend not to apply significant pressure on the axle. Disc brake systems are mounted on the fork and apply a load on the rotor, which is attached to the hub. There is an outward load on the hub axle that tends to push the axle out of the dropout.
It is especially critical the skewer be properly and fully secure on disc brake systems.

Non-quick release hubs use axle nuts outside the dropouts. The axle nut will have a washer built into the nut, or a separate washer. If the washer has teeth or knurling, these face the dropout to help secure the wheel. Lubricate the axle threads while the wheel is off the bike.

It is often easiest to install the front wheel when the bike is standing on the ground. The quick release skewer must be fully engaged on the dropout surfaces. By placing the bike on the ground, the axle will be fully up in the dropouts.

1. Check that the quick release skewer lever is in open position. Check that brake quick release mechanism is open.
2. Install front wheel between dropouts with skewer on left side (from rider's point of view). Pull wheel fully up into dropouts. For non-quick release wheels with axle nuts, washers go to outside of dropouts.
3. Rear wheels, pull back on rear derailleur to open chain. Place smallest cog between upper and lower sections of chain. Guide wheel between brake pads and engage smallest cog on chain.
4. Determine final closing position of hub quick release lever. Rotate front lever and adjusting nut so the lever will end up just in front of fork. Position the rear lever so it falls between the chain stay and seat stays. Reposition the lever as necessary if it will not fully close.
   
   
   
   
5. Adjust closing tension of quick release skewer. For most skewers, hold lever parallel to the hub axle, which is half way through its swing from fully open to fully closed. Tighten adjusting nut snug against dropout. Check results by moving lever back and forth through its swing. Lever should meet resistance to closing half way through its swing. Close lever fully.
   
   
   
   
   
   
6. For non-quick release wheels, tighten axle nuts fully.
7. Close brake quick-release mechanism. View wheel centering in fork. Wheel should be centered between fork blades. To adjust wheel centering, open skewer, move wheel either left or right until wheel appears centered, then close skewer. For non-quick release wheels, loosen axle nuts and center wheel, then tighten nuts fully.
8. Inspect brake pad alignment and centering by closing and opening pads with brake lever. If brake pads are not centered to wheel, see Chapter 6, Brake Systems. If wheel fails to adequately center in frame, either the frame or wheel may be miss aligned.
9. Spin wheel and double check pad alignment to rim. Be sure pads do not strike tire.
10. Orient skewer so lever will end up between the seat stay and chain stay, unless this prevents lever from fully closing.
11. Close brake quick release or attach MTB brake release wire.
12. View centering of wheel between chain stays and seat stays. Also sight rim centering to brake pads. Open skewer or loosen axle nuts and adjust as necessary to center wheel in frame. If brake pads are not adequately centered to wheel re-adjust brakes. If further attempts to align the wheel fail to adequately center it in frame, either the frame or wheel may be miss aligned. Seek a professional mechanic for help.

Note: So called "open cam" skewers may require more tension from the skewer. These skewer levers have the cam mechanism exposed, and should be lubricated often. Always check with skewer manufacturer for specific procedures.

Axle Nuts

Wheels may also be held on with a nut. The rear dropouts may also have a derailleur hanger that bolts to the dropout. There should be a bolt and nut that holds the hanger to the frame. The wheel installs over hanger bracket. The axle should extend to the back of this bracket. However, the left side axle will appear not to sit at the back of the dropout. This is because the right side is displaced forward by the hanger bracket. Center the wheel and fully secure nuts.

Front axles on some bike may include a tabbed washer. There will be a hole in the fork for the washer tab.

TUBULAR TIRE GLUING

Tubular Mounting

Typical Tools and Supplies Needed:

• Truing Stand to hold wheel. Use rags to protect stand from glue drips
• Acid brush or other clean narrow brushes, such as old tooth brush
• Acetone or other strong solvent
• Floor Pump PFP-2, or PFP-3
• Knife or scrapper

This article will discuss the mounting and gluing of tubular tires. The tubular tire is made from a tire casing that is then sewn around an inner tube. The stitching is covered with a strip of cloth called "base tape". The tubular is then glued to a special rim, called a tubular rim. The tubular system is not interchangeable with the common "clincher" system.

NOTE: The tubular tire system, even when mounted properly, is still susceptible to failure during use. Every precaution should be taken when bonding the tubular to the rim. At this time there are no industry standards for tubular mounting.

The basic principles that apply to gluing and adhesive bonding apply to tubular mounting. Generally, there should be enough adhesive to bond the tire and rim but not excessive amounts of glue. Excessive amounts of glue can become especially susceptible to failure from heat. There will be limits on the strength the bond between rim and tire.

• The tubular tire shape may not be a good match with the radius of a particular tubular rim. The tubular bond strength comes from the outer edges of the rim more than the center. If the tire is too small for the rim, there will not be good contact at the outer edges. In the cross section image below, there will be poor contact between tire and rim at the outer edges.
  
• Contact cements tend to soften and loose strength when they are heated. Hard braking during a descent can cause enough rim heat build up to soften tubular glue.
• Wet conditions tend to weaken the bond. Never glue a tubular out in rain or when the base surfaces are wet. Use care when washing tubular and avoid scrubbing the rim/tire interface.
• The tire is held on to the rim by glue, tension from the cord, and by air pressure. If a tire flats, the grip to the rim is weakened, and the tire is susceptible to coming off the rim.
• During use, the wheel and tire are subjected to several different types of stresses. The worst stress for the tubular system is a lateral load or lateral impact. Hitting bumps during a corner, where the wheel comes of the ground and then lands with an impact tends to push the tire sideways. This may cause the tire to come off the rim, either partially or entirely, which may result in a crash of the rider.

Most bicycle tubular glues are variations on contact cements. Tubular cement must hold the tire to the rim, but yet be somewhat flexible and giving when the tire is impacted laterally. Expoy or hard glue would tend to shatter when impacted rather than yield during a shock. Tubular cements tend to use volatile solvents that must bleed or dry out before the bond is fully secure. While the application technique is critical to maximum bonding strength, glue brands will vary in quality and adhesive strength. For more detail on tubular bonding see a technical article by Dr. Colin Howat at the Kurata Thermodynamics Laboratoryand download the aricles on Tubular Tire Adhesive Performance.

The safety of the rider depends on the best possible gluing procedures. A clean work area is important, as is time and patience. Ideally, it would be best to have three days to bond a tubular to the rim. This would allow for full drying of base coats. It is possible to glue a tire in a shorter amount of time, but it is important to understand that tubular adhesive require time for proper curing. The bond strength increases after the tire is initially mounted.

Gluing Procedure - New or Bare Rim

As with all bonding procedures, clean surfaces are important. Use a clean rag and a solvent that will not leave an oily film, such as acetone or alcohol, to clean the rim surface. An oily surface will tend to reply the adhesive. Allow rim to dry completely before continuing. Wipe with a clean cloth only. Always take precautions when using strong solvents such as acetone. Use protective gloves.

Carbon gluing surfaces have special considerations. Most manufacturers of carbon rims state that acetone is acceptable for cleaning the gluing surface. Contact manufacturer for their recommendations. Abrading the carbon can be useful for cleaning surface. This is especially true if there is "mold release" on the rim. This is a slick substance that allows the carbon to come out of the mold during manufacturing. Use only a medium grade sand paper or emory cloth (approximately 120 grit). Do not abrade down to the fibers themselves. Clean with an oil-free solvent after any sanding.

The tubular tire can be a tight fit to the rim. It can help to stretch the tire on a dry rim and inflate it to full pressure. Allow wheel to sit overnight. If time is an issue, the tire can be manually stretched by placing it over your back "bandoleer" style. Place a knee in the tire and stretch, using your back.

Inspect base tape. If the base tape is covered with latex, attempt to scrape clean with a sharp edge. If scraping does not appear to remove any glue, do not scrape further. If scraping appears to clean and clear the tape, continue until full width of tape is finished.

Ideally, a bonded joint should have a little glue as possible but without "starving" the joint. It typically takes quite a bit of glue, however, to get a full bond with many tubulars. If you are using the typical tube of glue, you can expect to use one tube per new wheel set. If the rim has a good base coat already, you will need less glue.

Apply a single coat of glue to the base tape. Inflate tubular until base tape rolls outward. Handle the tire by the sidewalls. Pinch tire in the middle to form a "figure 8". Apply a bead of glue a few centimeters at a time. Use an acid brush or tooth brush to spread the adhesive evenly across the base tape. Continue applying small sections of glue at a time until entire base tape is coated, including the area at valve.

Use care not to get glue on sidewall of tire. However, if glue does get on sidewall, do not remove with solvent. Simply allow drying and leave it alone. Hang tire off ground in a dust free environment allow to dry completely. A dry tire will be easier to handle when mounted to the rim.

It can be useful to hold the wheel in a TS-2 Truing Stand.Place rags to protect the stand from glue. Set the calipers to drag slightly on the rim braking surface. This will keep the rim from rotating while glue is applied to the top.

If rim has no base coat, apply a first coat. Apply an adhesive bead a short section of rim. Spread evenly the full width of the rim with a clean brush. Allow this first coat to completely dry, ideally overnight. Apply an additional coat and allow this coat to dry as well. The third and perhaps final coat will be used to mount the tire while it is tacky, and not completely dry. If there is a poor fit between tire shape and rim shape, more coats may be required.

It is important the adhesive be applied fully to the edges of the rim. Most of the holding power will come from the outer edges of the tubular rim. Test edges for glue, as seen in the image below:

After applying the final coat the rim, allow to only partially dry. This may take literally 60 seconds to only a few minutes, depending upon the glue and atmospheric conditions. Deflate the tubular until it is soft, but leave enough air so the tire holds its shape. This will help keep the sidewalls clean during mounting. Find a clean floor area to work on, such as tile, or even a toolbox lid. Do not mount on carpet, grass, or any surface that may contaminate the rim. Place the wheel vertically and place the valve in the valve hole. Begin to pull outward on the tire, holding the tire approximately 12-inches (30cm) to either side of the valve. Work the tire on a section at a time, while continuing to maintain pressure on the tire. The last section may be especially tight and difficult to get on the rim. Use thumb pressure to force tire onto rim.

After the tubular is mounted, IMMEDIATELY begin to true and align the tire on the rim. Sight the base tape on both sides of the rim. Generally, the base tape should appear even and centered. Check that the center of the tire is if fact centered on the rim. Pull and twist the tire as necessary. It can help to deflate the tire further to align, but re-inflate to check final alignment.

Check proper adhesion at this time. Roll the tire back in several places and inspect the glue at the rim and tire interface. Glue should be apparent at this area, as seen in the two images below.

A lack of glue will again show up at the edge of the tire and rim. The image below shows evidence of an inadequate amount of glue, referred to as a "starved joint". Remove this tire and apply more glue to the rim.

After the tire is aligned, inflate tire fully. High tire pressure will help press the base tape fully in the radius of the rim. It can also help to roll the tire along the floor while applying downward pressure.

Clean braking surface of any glue. Use a strong solvent and a rag is the rim is aluminum. For carbon rims, wipe off glue as best possible without solvent.

Lastly, the tire MUST be allowed to fully cure. This will require time for the glue solvent to bleed out. It is recommended that a tire be allowed to cure for 24-hours. Gluing and using a tire in a short amount of time will not allow proper bonding, and can lead to failure, no matter the brand of glue.

Mounting to Used Tubular Rims

The gluing procedures will vary depending upon of the condition of the used rim. If the rim already has a base coat, it typically can be re-used. The old tire, once removed, will give indications of the previous gluing. In the image below, the base tape shows very minimal contact.

There will often be a layer of dirt on the edges of used rims. Use a scraper and remove this glue and dirt. Remember, it is the edges that do most of the holding. It may be necessary to build up the previous coat. It is also possible that the old coat is thick in some area and bare in other. Apply glue accordingly. If the base coat is very old, or if it is dirty and contaminated, it should be stripped off. It is possible to use heavy bodied paint removers. Use a biodegradable remover when possible, and follow stripper directions.

NOTE: Do not use paint stripper on carbon rims. Many manufacturers recommend acetone to cut old glue. Contact manufacturer for their recommendations.

The base tape of a tubular is adhered to the tire with glue. If the base tape comes loose from the tire, it is difficult to repair to a "like new" condition. Use a thin coat of glue on the base tape. Install tire to a dry rim and inflate fully to push tape to rim.

It is impossible to fully inspect the mounting of a tubular without its removal. This of course is not practical. Roll the tire back away from the rim to inspect the glue at the rim/tire interface. If popping and cracking is heard, it is an indication the bond is old or there was inadequate glue in the bond. The tire would be suspect.

CARTRIDGE BEARING TYPE BOTTOM BRACKET SERVICE

Typical Tools and Supplies Needed.

• Park Tool BBT-2 (a splined driver to fit the bottom bracket rings).
• Park Tool BBT-8 for Truvativ®, and Bontrager® cartridge bottom brackets.
• Park Tool torque wrench TW-2 (or other torque wrench, 3/8" drive). Optional, but recommended.
• A 32mm headset wrench, or a large adjustable wrench, if you do not have a torque wrench.
• Medium grade thread locking compound, such as Loctite #242
• Anti-seize, if frame is titanium or aluminum.
• Grease, such as Park Tool PPL-1 Polylube 1000

This article will discuss the removal and installation of the common cartridge bottom brackets of the three-piece cranksets.

Most cartridge bottom brackets are held by retaining rings or cups on either side. The description below is based on the Shimano® brand of bottom bracket, but most other cartridge type bottom bracket bearing units install in a similar fashion. NOTE: Shimano® XTR BB950 bottom bracket and Dura-Ace BB-7700 bottom brackets are adjustable type bottom brackets. See Adjustable type Bottom Brackets

For the External Bearing System Cranksets, such as Shimano® Hollow Tech II bottom bracket-crankset systems, see External Bearing System Service.

There are two different styles of Shimano® cartridge bottom brackets. One type has a fixed flange on the right side (drive side). The other type has a fixed flange on the left side (non-drive side). Each one uses a removable ring opposite the fixed flange. See the figure below.

There is a fairly simple test to determine if the bottom bracket bearing is worn out. Shift the chain to the inner most rear sprockets front and rear. Drop the chain off the smallest front ring, and arrange it so it will not strike the chainrings. Spin the crank while holding the bike with one hand. If you feel an obvious rumbling or grinding feeling, the bearing are wore out and the unit should be replaced. Very worn bottom brackets will actually make a grinding noise.

Removal of Cartridge Bottom Bracket

Begin bearing service by first removing both cranks. For square taperred spindle types, see Crankarm Removal. For round splined type spindles and arms see Splined Arm Removal.

Some bottom bracket models use a steel or aluminum ring on one side and a plastic ring opposite. On these models, remove the metal side first regardless of left or right side. Otherwise, insert BBT-2 fully into splines on left side. Some brands use an eight notched ring, which will accept the BBT-8. Use care to hold either tool firmly in place. Remove the non-drive side by turning counter-clockwise. For some models, this removes the ring, in some models this pull the cartridge body out.

Insert BBT-2 or BBT-8 fully into splines on opposite side. For non-drive side, remove by turning counter-clockwise. For drive side, turn clockwise to remove.

The spline system used on many cartridge bottom bracket is very shallow. If the spindle is hollow, use the rear hub skewer to hold the tool firmly in place. When using this technique to remove the spindle, break the threads free, then loosen the skewer as the cup comes out.

THREADING NOTE: Most modern bikes use an ISO thread standard for the bottom bracket. The left side thread is a right-hand direction thread, which tightens clockwise and removes counter-clockwise. This standard is also called English or BSC. The right side (drive side) thread is a left-hand thread, which tightens counter-clockwise and remove clockwise. There are some exceptions to the ISO. Bikes made in Italy may use "Italian" threading, with both drive and non-drive sides right hand thread. There may be markings such as "36 x 24" on the cups. Older bikes from France may have right hand threads on both sides (35mm x 1mm). It is especially recommended for bikes with a right-hand thread for the drive side to use a thread locker in addition to full torque. See more on thread preparation and thread lockers a Basic Thread Concepts.

Below is an image of the common ISO threaded cups. Note the threads of the left-threaded (drive side) cup slope upward to the left. Threads of the right-threaded (non-drive) cup slope upward to the right.

Cup direction for non-drive (left side of bike) and drive side (right side of bike) are shown below for the common ISO/English bottom brackets.

Non-drive (left side) cup direction.

Drive side (right side) cup direction.

Seized Cups

It can occur that the cup becomes seized in the frame. Be sure to double check thread direction when in doubt. The common 20-tooth internal spline cup has shallow splines for tool engagement. Use a long bolt to secure the BBT-2 to the cup. A skewer can be used if the spindle is hollow. Use a bench vise to hold the tool. The frame become the lever. Again, double check thread direction before turning. Soak threads with a penetrating fluid before attempting removal.

Cup and Lockring Type

There several variations on the cartridge bottom bracket system. One type uses cups and seperate lockrings on both side. The bearings are typically common industrial types. The cups are removed and then the bearings replaced. In the image below, the cup looks similar to the adjustable bearing types. A lockring spanner is used on the lockring, and then a spanner such as the SPA-4 is used in the cup. The cup is run up to the bearings and then the lockring is secured. There is no bearing adjustment in this sytem.

Installation of Cartridge Bottom Bracket

Begin by preparing the threads of the bottom bracket. Steel bottom bracket frame shells with aluminum or steel lockrings, use a thread locking compound such as Loctite® #242. (Note: the #242 and comparable thread lockers are considered "service removeable". This means that the parts are removeable with normal tools and without taking extreme measures.) Place a bead of the compound around the first three threads on both lockrings. Thread locking compounds are available from some bicycle stores, automotive parts store and better hardware stores. (If no thread locking compound is available, grease threads heavily or apply anti-seize.) For more on thread preparation see Basic Threadr Concepts.

If the bottom bracket frame shell is aluminum or titanium, use anti-seize compound. Even if lockrings are steel, use anti-seize. Anti-seize is available at some bicycle stores, hardware stores, or automotive parts stores. Grease can be used in place of anti-seize, but anti-seize is more durable and provides better lubrication during tightening. Apply this only to the threads.

Plastic lockrings or cups need only grease on the threads. Do not use thread lockers on plastic as the chemical may cause the plastic to become brittle.

It can sometimes happen a bottom bracket can creak where the lockring or cups meet the bearing body. To prevent this, apply a thread locking compound such as Loctite #242 to the inside area of removable ring, where it meets the body. This will help prevent any creaking in the future. With plastic rings, do not apply any thread locking compound.

Look on body of cartridge for "L" and "R". "L" goes to left side of bike, and "R" goes to right side of bike. For most bikes, the right side ("R"), has left-hand direction threads, thread this side in turning counter-clockwise. The left side ("L") has right-hand direction thread, so thread this side in turning clockwise. (See THREAD NOTE on thread direction above.) Thread the cartridge body into bottom bracket by hand, being careful not to cross thread.

Use BBT-2 or BBT-8 as appropriate to snug fixed flange against face of bottom bracket.

Thread in removable ring to appropriate side.

Secure removable ring to at least 360 inch pounds using torque wrench. If you are using hand wrench, and are holding the wrench 6 inches from axle, apply 60 pounds of pressure… which is tight. By securing removable ring, you are securing the other side at the same time. Removable ring pushes against fixed flange.

Install cranks.

EXTERNAL BEARING CRANK SYSTEMS (HOLLOW TECH II, MEGAEXO, GIGAXPIPE, X-TYPE) Typical Tools and Supplies: Park Tool BBT-9 Hex Wrenches Thread preparation, options include Polylube® 1000 grease, anti-seize, and thread lockers This article will discuss service of the "external bearing cranksets." Examples are Shimano® Hollowtech II, Race Face® X-type Crankset and FSA® MegaeXo, and Truvativ® Giga X Pipe. These systems integrate the bottom bracket bearings, crank and spindle. The spindle is a permanent part of one arm. The opposite arm slides onto the spindle splines and is then secured. While conventional bottom bracket system have the bearing inside the bottom bracket shell, these types of cranksets have external bearings that sit outboard of the shell face. Example of these systems are Shimano® Hollowtech II, Race Face® X-type Crankset and FSA® MegaeXo, and Truvativ® Giga X Pipe. The external crankset bearing systems integrate the bearings, cranks and spindle. The bearings sit outside the face of the bottom bracket shell face. The spindle is a permanent part of one arm. The arm slides onto splines and is then secured. These systems use a cartridge bearing. The bearings cups of these systems thread into the bottom bracket, and press against the shell face. The bearings then sit outside of the shell. It is important that the left and right shell surfaces are adequately machined square to the threads and one another. Miss aligned shell faces can cause the bearing cups to twist as the seat into the bike. MTB-Type Cranksets The table below outlines the spacer arrangement for the Shimano® XTR FC-M960, XT FC-M760, Saint FC-M800, Race Face® X-type, and FSA® MegaeXo bottom bracket bearings as installed into 68mm and 73mm shell widths. The E-type brackets and International Standard Chain Guide bracket options are also listed. The bearing cups are of a similar design, and cups are designed to be spaced 75.5mm apart. Three spacers of 2.5mm are supplied to achieve this width. E-type front derailleur brackets, or a chain guide mount, are counted toward the width total. Bottom Bracket Shell Width Front Derailleur or Chainguide Non-Drive (left side of bike) Drive Side (right side of bike) 68mm Clamp on 2.5mm spacer 2 x 2.5mm spacers 68mm E-type derailleur bracket 2.5mm spacer 2.5mm spacer plus E-type bracket 68mm Chainguide system 2.5mm spacer 2.5mm spacer plus chainguide 73mm Clamp-on No spacer 2.5mm spacer 73mm E-type front derailleur No spacer E-type bracket 73mm Chainguide No Spacer International Standard Chain Guide bracket only             NOTE: The Shimano® FC-M761 is sometime used with a "crankcase" shifting system. More spacers are included for this model:68mm shell band type: Left cup-2.5mm spacer; Right cup-1 each of 2.5mm, 0.7mm, and 0.8mm 68mm shell chaincase stay type: Left cup-2.5mm; Right cup- chaincase stay, 0.7mm spacer, 2.5mm spacer 68mm E-type bracket: Left cup- 2.5mm spacer; Right cup- E-type bracket, 2.5mm spacer, .8mm spacer 73mm band type: Left cup- no spacer; Right cup- no spacer 73mm chaincase stay type: Left cup- no spacer; Right cup- chaincase, 0.7mm spacer 73mm E-bracket type: Left cup- no spacer; Right cup- E-bracket only Road-Type Cranksets The Shimano® Dura-Ace FC-7800 crankset, Truvativ® and FSA® road cranksets are designed for a 68mm bottom bracket shell. No spacers are required or used for the road systems. Frame Preparation The bearing cups thread into the bottom bracket shell and press against the shell face. It is important that the left and right shell face surfaces be machined square to the threads and one another. If a bearing cup is secured to a shell with miss aligned faces, the two bearings will not align properly with each other. Unlike conventional cartridge bottom brackets, these bearings use the shell face as a reference for alignment. Shell faces that are not parallel may cause a twist or load to the bearings. See Bottom Bracket Machining for details on facing and machining. Prepare threads of shell with either grease, anti-seize, or a mild thread locker. For more on thread preparation, see Basic Thread Concepts. Install correct amount of spacers on cup marked with "R" (left-threaded cup) and install dust sleeve on cup. Thread cup counter-clockwise into right side (drive side) of bike. Use care not to cross thread cup. Tighten fully, approximately 305 to 435 inch pounds. When using the BBT-9, and grabbing the tool about 6-inches (15 cm) from the cup, apply about 60 pounds (27 kilograms) of effort to tighten the cups. Install correct spacers as needed on cup marked “L” (right-threaded cup). Thread cup clockwise into left side (non-drive) of bike and tighten fully as before. Shimano® Hollowtech II Procedures The Shimano® XTR FC-M960 Hollowtech II is seen below. The Dura-Ace system is similar in design, but uses different cups and no spacers. The right side arm contains the spindle. The left arm is secured with two pinch bolt. A crank cap is used on the left arm for bearing adjustment. The cap does not hold the crank, it is only for adjustment. After bearing cups are installed, grease spindle surface and place right crank with spindle through the right side cup (drive side). Push from right side until spindle comes out left cup. Fit is snug, and in some cases gentle use of a mallet may help. If spindle appears to catch and will not come out non-drive side cup, may be an indication that shell faces need machining. Grease splines of spindle and install left arm. Notice splines are keyed, and left arm will only install 180-degrees opposite of right arm. Grease threads of arm cap and thread cap into spindle. This cap acts only to push arm fully over to cup bearing. This cap does not tighten the arm onto the spindle. IMPORTANT NOTE: Secure cap gently. Use the eight sided stud a the end of the BBT-9 and tighten only 4 to 6 inch-pounds. Over tightening will side-load the bearing and cause premature wear. Spin arm to test. Use a hex wrench and secure bolts at compression slot. Secure to 88 to 132 inch-pounds. Secure bolts evenly, working first one and then the other. Disassembly IMPORTANT NOTE: First, loosen the two left crank pinch bolts at end of arm. Next, loosen and remove arm cap and slide arm off. It it sometimes necessary to gently tap arm with mallet. Pull crankset to right to remove right arm and spindle. Use BBT-9 to remove both cups. Non-drive side removes counter-clockwise. Drive side removes clockwise. FSA® MegaeXo Crankset The FSA® system shares some of the same service features as the crankset previously described. The right side arm contains the spindle. The left arm is pressed gently against the bearing cups by the arm cap. Begin by installing bottom bracket bearing cups as described above. The arrangement of spacers is the same as shown in the table. Grease spindle surface and press right crank through right side. The fit is snug, and mild use of a mallet may at times be useful. Place left arm on to spindle splines. Grease thread of crank cap and thread into spindle. Use a 8mm hex wrench and GENTLY snug the cap. The left cap simply bring the arm over to the bearing. It is used as a bearing adjustment, and it does not secure the right arm. Secure the left crank with the pinch bolts in the arm. Alternately tighten each bolt until both are fully tight. Check arms for play. Race Face® X-Type Service The X-type crankset left arm has a permanently pressed spindle. The spindle has ten splines, but these are not symmetrically aligned. The ISIS Drive® system arms will not fit this spindle. The drive side arm is secured to the spindle with a crank bolt. Begin installation by installing bearing cups as describe above for Shimano®, using the BBT-9. Arrange cup spacers as described in the table above. The left crank uses an elastomer washer that will preload the bearings. The chainline is adjusted with 1mm spacers. No spacers are used on the right arm to achieve the 48mm chainline. One spacer on the right arm will give a 49mm chainline, and two spaces a 50mm. Grease spindle surface and install spindle through left side on bike after installing appropriate chainline washers. The fit of the spindle may be snug and some mild force may be necessary. Use a rubber mallet with care. Guide the spindle through the right cup, and install any needed chainline washers. Grease internal threads of spindle, and grease spindle splines. Align right arm 180-degrees from left arm and begin to turn bolt clockwise using a 8mm hex wrench. Secure bolt to a torque of 360 inch-pounds to 600 inch-pounds. Bolt will come to a “hard stop” as the arm fully presses to spindle. The X-type right side crank has a one-key release system. The retaining cap use a left-hand thread, and is secured to the arm with a 10mm hex wrench. It is not necessary to remove the one-key system. To remove the arm, use a 8mm hex wrench on the crank bolt and turn counter-clockwise. One-key system will remove arm from the spindle. After removing the right arm, pull the left arm to remove. It may be necessary to use a mallet and tap spindle to free the arm. The image below shows the one-key system. It is not necessary to remove the system for either removal or installation. Truvativ® Giga X Pipe The Truvtiv® Giga X Pipe is a road-type crankset system. The bottom bracket cups are designed for the 68mm bottom bracket shell width. Cups are marked with thread direction arrows and torque specifications. The spindle is a permanent press fit into the driveside arm. Each cup is tightened into the bottom bracket shell as with the systems above. No spacers are need or required. Both cups are tighten to 300-360 inch-pounds. Grease the splines and surface of the spindle and insert through the right side cup. Install left arm and tighten. There is no "bearing adjustment". The drive side cup has a rubber lip that compresses as the arms are pressed. As the splined left arm is tightened, it compressed the lip. Tighten left arm to 360 to 420 inch-pounds. The left arm has a one-key release system. No puller is required to remove, simply use 8mm hex wrench and turn crankbolt counter-clockwise.

ADUSTABE TYPE BOTTOM BRACKET SERVICE

Useful Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• Lockring Spanner, such as HCW-5
  Shimano® Dura-Ace 7700 and XTR 950 lockrings use BBT-7.
• Adjustable cup spanner, such as SPA-1 or SPA-6. Shimano® Dura-Ace adjustable cup uses BBT-2.
• Grease PPL-1 Polylube® 1000
• Marking pen, and masking tape.
• Rags

This article will discuss the service of adjusting bottom bracket bearings. It will also review the types of tools required. The basic concept for bearing adjustments is to get the bearings adjusted as loose as possible but without play. This can be done by purposely beginning with play in the adjustment, and then tightening in small increments until play is gone. With much use the bottom bracket bearings, cups and cones may become worn and pitted. In this case, a smooth bearing adjustment will not be possible. The bottom bracket will need a complete overhaul and most likely new parts as well.

There are three common types of bottom brackets.

1. Three piece bottom bracket- Cartridge type: Bikes made the last few years tend to come with a "cartridge" bottom bracket. For the most part, these are unserviceable, and the entire unit is simply removed and replaced when they wear out. They can not be greased or adjusted before that time. Some brands use common industrial bearings, just like ones found in cars, pumps, electrical motors, etc. Generally, the bearings are intended to be used until they wear out. With most brands, the entire unit including the spindle is replaced. For service of cartridge bearing bottom brackets, see Cartridge bearing type bottom bracket service.
2. Three piece bottom bracket- Adjustable type: These usually contain four major pieces: lockring, adjustable cup, spindle, and fixed cup. The left side lockring has notched rings, and the adjustable cup may have holes for a pin spanner, or notches for a wrench. The right side cup will have wrench flats, but no lockring. Cups may be removed and replaced separately, and the spindle may be replaced separately. A set of round ball bearings are found in each cup, typically eleven ball per side of 1/4-inch diameter. This type of bottom bracket may be cleaned, greased, and adjusted.
   
   
   An older adjustable type bottom bracket.
3. One-piece or "Ashtabula" bottom brackets: These are found on some older Schwinns, juvenile bikes, some BMX bikes and on many department store-type bikes. One piece of steel forms the crankarms and goes from the pedal, through the bottom bracket, to the other pedal. See One-piece Crank Service for procedures.

Bearing Adjustment and "Feel"

Bearing surfaces are made from hardened steel. The surfaces are cut typically by grinding. Round ball bearings roll on the curved surface of the cup and cone. Even the highest quality bearing surfaces will have slight grinding marks. In the left image below is a high quality cone magnifed two hundred times. Notice the parallel marks from the grinding stone. Also note a slight pit from wear. The right hand image is a bearing magnified the same amount. It does show some surface marking, but is generally smoother than the cone or cup. Bearing surface smoothness will vary between manufacturers and between models. Some bearing system will simply "feel" smoother because they are smoother. This is why it is difficult to adjust by using a subjective feeling of smoothness. Generally, adjust bearings for the loosest setting that has no knocking or play, regardless of this relative smoothness.

There is a fairly simple test to determine if the bottom bracket bearing is worn out. Shift the chain to the inner most rear sprockets front and rear. Drop the chain off the smallest front ring, and arrange it so it will not strike the chainrings. Spin the crank while holding the bike. If you feel an obvious rumbling or grinding feeling the bearing are wore out and the unit should be overhauled. It will be likely internal parts will be required. Typically, the spindle will wear out before the cups. The ball bearings tend to wear out last.

Adjustment Procedures

The adjustment procedures below assume the bottom bracket axle, cups and bearings are not badly worn. If a good adjustment cannot be found, it is likely the parts are wore out and need replacement. Trace the bearing path with a ball point pen. Pitting

When adjustmenting the bottom bracket, work in small increments. To help in this, begin by taking about two inches of tape and making marks on one edge every 1/8". Stick the tape on the left side of the bottom bracket shell so the marks face outward. These will be reference marks when adjusting the bearings and represent the small increments used when turning the adjustable cup.

Adjustable bottom bracket consist an axle and two cups, one on either side of the bike. The drive-side cup (right side) is sometimes refered to as the "fixed" cup because it is secured into the frame. Adjustments are made to the non-drive (left side) cup. If you did not assemble the bottom bracket yourself, it is recommend you check the security of the drive-side cup. A drive-side cup will not allow a proper adjustment. When overhauling and regreasing the bottom bracket, the drive-side cup can remain in place.

1. Remove crankarms. See Crankarm Removal.
2. Loosen left side lockring by turning counter-clockwise.
3. Loosen left-side cup by turning counter-clockwise 1/2 turn.
4. Hold fixed cup spanner firmly to right side fixed cup and check its security by tightening counter-clockwise. If cup seems tight, it is tight.
5. Re-install right crankarm only and tighten. This will be used as a lever to check for play in adjustment.
6. Gently tighten (clockwise) the adjustable cup, just to the point you can feel it bump into the ball bearings.
7. Use marker and make a line on the cup face. Have a look at the tape and note which mark aligns with cup reference mark. It is also possible to use a mark already on the cup, such as the first letter of the manufacturer if the cup is stamped.
   
8. Hold the adjustable cup firmly with the correct spanner. Using the lockring wrench, tighten the lockring very tight.
9. Check for knocking in the spindle: Grab end of right crank arm and push back and forth. Repeat this as you rotate the crankarm all the way around.
10. If there is no play, adjustment may be too tight. Loosen lockring and loosen cup to create play. Secure lockring and check for play. Once you have play, move to step 11.
11. If there is knock (play), make note of which tape mark aligns with the cup mark. Loosen the lockring counter-clockwise. Move the adjustable cup clockwise a small amount using the 1/8" mark of the reference tape. Secure the lockring again, check for play again.
12. Repeat tightening one mark at a time until play disappears, checking for play as the right crankarm is in different positions. You want the adjustment to be as loose as possible, BUT WITHOUT KNOCKING.
13. Use mild solvent to remove pen mark from cup or frame.

NOTE: If bottom bracket bearing surfaces are worn out, it will not be possible to have a smooth adjustment when play disappears. The bottom bracket parts will need replacement.

Shimano® Dura-Ace and XTR Adjustable bottom brackets

These bottom brackets use a cup and cone type system. The bearing adjustment is from the left side, similar to other adjustable bottom brackets. The bottom bracket uses both a ball bearing and a needle bearing system on left and right side cups. When overhauling, it is recommended to leave the needle bearing and ball bearings in the cup. Clean by flushing with solvent.

Dura-Ace

The non-drive side (left) of the Dura-Ace bottom bracket uses 20 internal splines in the cup. These tend to be shallow. When adjusting the Dura-Ace, use the BBT-2 to adjust and hold the cup. Secure the lockring with the BBT-7 lockring spanner. Use care to hold the BBT-2 fully into splines of the cup. Note in image below the right crankarm is mounted. Use this as a lever when checking for play.

XTR

Adjustable type XTR BB-950 use the BBT-8 for both drive and non-drive cups. The lockring is the BBT-7, as seen in the image below. The procedures for service is similar to the procedure described above.

Bottom Bracket Tapping, Threading, Chasing and Facing

Typical Tools and Supplies Needed

• Repair Stand
• Bottom Bracket Tap Set (tapping and facing) BTS-1.
• Bottom Bracket Facing Set (facing only) BFS-1.
• Cutting Fluid CF-1.
• Measuring Caliper
• Thread pitch gauge
• Degreaser, to clean frame after work, such as CB-2

This article will discuss use of the Park Tool BTS-1 and the Park Tool BFS-1. See also related articles:

• Service of cartridge bearing type bottom brackets
• Service of adjustable type bottom brackets/A>
• Service of external bearing crankset systems
• Basic thread concepts

Most bottom bracket shells have an internal thread to accept bottom bracket bearing units from numerous manufacturers. If these threads are not in acceptable condition, they may need preparation. Threads may need realignment, or may have weld splatter from manufacturing that prevents the threading of the bearings. Shells may be out of round due to welding during manufacturing. Additionally, some bearing system benefit from having the faces of the shell square to improve bearing adjustment and bearing longevity. If the shell faces are deformed, and are not parallel to one another, the left and right bearing may not be concentric to one another. Machining the shell face improves concentricity.

The Park Tool Bottom Bracket Tapping and Facing Set BTS-1 will prepare thread and also allow facing of the shell. It consists of two handles, two taps, and a facer. The taps are installed and are left in place as guides for the facer, if facing is desired. Facing is done with hand pressure, which is typically adequate for most bikes.

The Park Tool Facing Set BFS-1 consists of one handle with spring pressure system, two threaded bushings, and one facing cutter. It is intended for facing only. Threaded bushings require a properly threaded bottom bracket. If the threaded bushings do not thread into the shell, the shell must be tapped. The spring pressure system on the BFS-1 allows much greater load to be applied during facing, and will remove material in a shorter time as compared to the hand pressure of the BTS-1 system.

The common thread norm for the bottom bracket-bearing unit is 1.37” x 24 TPI. In some countries outside the USA, this is referred to as 35mm x 24 TPI. This is because the number 1.37" has little meaning, and the term 35mm is common terminology. It has been the habit to name the thread standard by the country of origin, even if the thread is no longer used there. France for example now uses the ISO 1.37" x 24 TPI, but the 35mm x 1mm is called "French" threading. The following is a table of threading used in bicycle bottom brackets:

Bottom Bracket Thread Name	Nominal Thread Description	Cup Ouside Diameter	Shell Inside Diameter
ISO/English	1.37” x 24 TPI Park Tool tap part number #691-RH (for non-drive) #692-LH (for drive)	34.6-34.9mm Left-hand thread on drive side	33.6-33.9mm
Italian	36mm x 24 TPI Park Tool tap #693 (two required)	35.6-35.9mm Right-hand thread both sides	34.6-34.9mm
French obsolete, rarely seen	35mm x 1mm	34.6-34.9mm Right-hand thread both sides	33.6-33.9mm
Swiss	35mm x 1mm	34.6-34.9mm Left-hand thread drive side	33.6-33.9mm
Whitworth (Obsolete found on older English 3 speeds)	1-3/8" x 26 TPI	34.6-34.9mm Left-hand thread drive side	33.6-33.9mm

IMPORTANT NOTE: The common ISO/English thread standard found on most bikes uses a left-hand thread on the drive side of the bike. The drive side is also called "chainring side", and is the right side as seen from sitting in the saddle. A left-hand thread on the drive side is done so the cups tends to be self tightening. This may on the surface appear counter-intuitive, but because the ball bearings are rotating, the load direction of pedaling is reversed. The taps of the BTS-1 and the threaded bushings of the BFS-1 are marked for thread direction with LH, for left-hand, and RH for right-hand. These marking DO NOT refer to side of bike. Some bottom brackets are marked with LH and RH that do refer to side of bike. Always check slope of thread if in doubt.

The image above shows threaded bushing of the BFS-1, a cartridge bottom bracket, and taps for the BTS-1. Notice cartridge bottom brackets with "Left" and "Right" marking are referencing the side of bike, while bushing and taps reference thread direction.

Procedure for Tapping and Facing Using BTS-1

The image below shows the bottom bracket taps in left-hand thread and right-hand threads. Notice red arrow pointing at first section of each tap. A right-hand threaded tap begins with the lead thread on the right. A left-hand threaded tap begins with the lead thread on the left.

Inspect lead section of each tap to confirm thread direction.

1. Identify thread type of bike. Measure bottom bracket cups removed from the shell and check chart above.
2. Check taps are correct on BTS-1. If ISO/English thread, identify left-hand thread for drive side (right side) of bike.
3. Install taps simultaneously into bottom bracket, with correct tap on correct side. This ensures each tap is aligned as it starts into the internal thread.
   
   
   Guide taps simultaneously into shell.
4. Stop and apply generous amounts of CF-1 cutting fluid.


Use a good quality cutting fluid applied often during the cut.
5. Turn one tap until tap is recessed in bottom bracket shell. Turn tap in SLOWLY ¼ turn, then back slightly, then advance again ¼ turn. This breaks the chip created by the cutting teeth. Add more cutting fluid each full turn.
6. Turn other tap until tap is recessed in shell, again repeating process above.
   
   Taps must be recessed in shell if facing is also performed.
7. If facing shell is desired, remove one tap handle by pulling outward on handle. Install facing tool #690 on tap handle.
8. Apply cutting fluid to face of cutter, and bring gently into contact with shell.
9. Hold in middle of handle, and turn CLOCKWISE while applying pressure. DO NOT rotate facer counter-clockwise, this may dull the facer teeth.
   
10. Pull back on handle after several turns and check progress.
    
    Check the progress of the facing every few turns.
11. When cut metal appears in a complete circle, facing is finished. The facing cut in complete when there is a flat milled surface in a 360-degree circle around the shell face. The full width of the shell face does not need to be cut. Continue cutting if necessary.
    
    Note shell face near red arrow. Full width of shell is not needed. Black paint here represents a low area to the lock ring or bearing cup.
12. After cut is complete, turn facer gently on shell to remove burrs.
13. Remove second handle, install on other side and repeat process on second face.
14. Remove facer from handle and install handle into tap. Remove both taps. Use care to unthread taps simultaneously to prevent thread damage.
15. Clean taps, and clean inside of bottom bracket shell using a brush.

Procedure for Facing Using BFS-1

The BFS-1 uses two threaded bushings that are installed inside the shell. The internal threads must be acceptable in order for the threaded bushings to fit. Use the BTS-1 if the threaded bushings do not thread in place.

The image below shows the left-hand thread and right-hand threaded bushings of the BFS-1. Notice the thread slopes at an angle. The left-hand thread direction slopes upward to the left. The right-hand thread direction slopes upward to the right.Inspect thread slope to determine thread direction

1. Check threading direction of threaded bushings.
2. NOTE: Before installing threaded bushings, GREASE or use an antiseize both bushings and inside frame shell.

3. If there is a left-hand threaded guide, install into the drive side (right side) of bike. Use handle of BFS-1 to thread bushings until both are recessed into frame.
4. Note: If threaded bushings are difficult to install, remove and tap shell with BTS-1. Threaded bushing must be recessed into bottom bracket shell.
5. Place handle with #690 facer through either side. Install on other side washer, spring, keyed spacer, and tension adjusting nut.
   
6. Turn handle clockwise only to begin cutting. Increase pressure as necessary by tightening tension adjusting nut.
7. After making several rotations, loosen the adjusting nut and draw the #690 cutter away form the shell face to inspect cut. See explanation in BTS-1 procedure above for a complete cut.
8. After cut is complete, loosen adjusting nut and use light-hand pressure at center of handle to remove any burrs left by #690 cutter.
9. Remove adjusting nut and remove handle from shell. Remove #690 facer and use handle to threaded bushings from shell. Clean frame of any cutting fluid.
10. Clean facer, threaded bushings, and inside of bottom bracket shell. Do NOT use compressed air to clean metal shavings.

NOTE: All cutting tools will eventually require re-sharpening. With use, the cutting edge will dull. While there are many variables that play a role in how long a cuttisng tool will stay sharp (e.g. technique used, amount and type of lubrication used, type of material being machined, etc.), in general the tool re-sharpened once a year. Tools can be re-sharpened by The Tool Grinder (phone 805.574.0414), a service that specializes in sharpening cutting tools for the bike industry, or by a local industrial tool grinding company.

ONE-PIECE BOTTOM BRACKETS (ASHTABULA)

Typical Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• HHP-2 bearing press (for installing cups only)
• HCW-7, (30 and 32mm common) or large adjustable wrench
• Pin Spanner SPA-4 for one-piece cranks
• Grease PPL-1 Polylube® 1000
• Rags

This article will discuss service on one-piece crank bottom bracket bearings("Ashtabula").It will also discuss pressing the three-piece cartridge bearings into the Ashtabula bottom bracket shell.

The One-piece bottom bracket and the one-piece bottom bracket shell are found on some older Schwinn® bicycles, many juvenile and BMX bikes, and on many department store-type bikes. One piece of steel forms the crankarms and goes from the pedal, through the bottom bracket, to the other pedal. This crank also acts as the bottom bracket bearing axle.

The one-piece crank system can be replaced with a three-piece bottom bracket system, using a different bearing system and a spindle that is separate from the cranks.

One-Piece Bottom Brackets

The crankarm is threaded in the middle, and acts as the bottom brackets spindle. The crank drive side threading is a right-hand threading, and the non-drive side (left side) is a left-hand threading. It is necessary to first remove the left side pedal in order to remove the crank. Turn the left pedal axle counter-clockwise to remove. See Pedal Removal for more detail.

1. Loosen left side locknut clockwise using the HCW-7, or large adjustable wrench. Locknut is left hand thread on one-piece cranks. Use opposite arm for leverage.
   
2. Remove washer. Note washer has keyed tab that alings in slot in thread.

3. Remove adjusting cone clockwise with SPA-4 spanner.

4. Pull both left right bearing retainers out of cups. Arm will not remove with bearing in place.


5. Slide arm out of bottom bracket shell.
6. Inspect drive side cone for wear. It is not necessary to remove cone for cleaning. If replacing, clamp arm in vise with right side cone facing up. Remove drive side cone clockwise.


7. Clean and inspect parts. Inspect bearing cups in frame.

Cup replacement

Generally, if the bottom bracket is overhaul, there is no reason to remove the cups. If the cups are worn, or if the bottom bracket is being replaced, the cups must be removed. Use a punch and hammer to remove the cups. Tap on alternate sides until cup is removed.

Assembly and Adjustment

1. If the cups were removed, begin by installing cups. Use the HHP-2.
   
2. Install drive side cone, if necessary. A thread locker is recommend.
3. Pack bearings fully with grease.
   
   
4. With bearing on cone, feed arm into bottom bracket and through shell. Install non-drive side bearing, and thread on adjusting cone. Adjusting cone is a left-hand thread, turn counter-clockwise to intall.
5. Install keyed washer and locknut.

The HHP-2 can also be used to press the cartridge bearing style cups.

Bearing Adjustment

The basic concept for bearing adjustments is to get the bearings adjusted as loose as possible but without play. This can be done by purposely beginning with play in the adjustment, and then tightening in small increments until play is gone. With much use the bottom bracket bearings, cups and cones may become worn and pitted. In this case, a smooth bearing adjustment will not be possible. If bottom bracket is correctly adjusted, but bottom bracket grinds when spun, cups and or cones are worn and should be replaced.

1. Begin with locknut loose. Turn adjusting cone counter-clockwise until it hits the ball bearing, then turn back clockwise to loosen 1/4 turn.
2. Secure locknut
3. Grab end of crankarms and rock sideways to check for play. If play is present, loosen locknut and turn adjusting cone counter-clockwise slightly to tighten. Re-secure locknut and check again.
4. Repeat process of checking for play and re-tightening cone a slight amount until no play is felt. NOTE: The one-piece crank systems do not use a polished bearing system. There will be some roughness to a correctly adjusted bottom bracket. Adjust as loose as possible but without play in the bearings.

REMOVAL OF CHAINRING SPIDERS This article will discuss the use of the BBT-8 to remove some crankset spider lockrings Some MTB crankarms use a detachable spider or chainring mounting arms. These spiders use internal splines at the center, and are held to the crankarm with a lockring. The Park Tool BBT-8 is designed to fit this eight notched lockring. The tool also fits the cups of the Shimano® XTR 950 Bottom Bracket. If the lockring becomes loose, it will cause a creaking sound when the bike is ridden, similar to a loose crankarm bolt. Check the security of this ring using the BBT-8. Procedure for Servicing Lockring Remove the crankarm from the bike. For help removing the crankarms, click here Notice there is a snap ring over the lockring. Remove this with a screwdriver. Place the BBT-8 in the notches. Use the pilot to hold the tool securely to the crankset. The pilot is double sided. The smaller side fits the 8mm crank bolts of the square type spindles, and the larger size fits the 15mm bolts of the spline spindle types. Insert the bolt back in the arm and thread it snug into the pilot. Hold the crankset secure in the soft jaws of a vise. Use a rag to minimize any scratching on the arm. Loosen the lockring counter-clockwise. Note the BBT-8 has a 36mm wrench flats. A HW-2 wrench in preferred, as it wraps around the tool flats. The TWB-368 crow's foot extension will also fit the flats, and allows measured torque when re-securing when used with a torque wrench. Grease or oil the threads. Alternatively, you may also apply a mild thread locking compound such as Loctite® #242. Secure the lockring fully. Shimano® recommends 443-620 inch-pounds on their lockring. If you are attempting to torque by feel, that is 38 to 50 pounds of effort on a wrench held twelve inches from the center of the lockring. Again, use of the TWB-368 allows measured torque with the TW-2 torque wrench. Reinstall the arm. This should keep the spider secure and noise free. If the bike was ridden much with the locking loose, damage to the spline system may occur. Replace the arm if this is the case.

BRAKE LEVERS

Useful Tools and Supplies

• Repair Stand.
• Hex wrenches

This article will discuss the cable (inner wire) installation in brake. MTB levers secure to the handle bar by a clamp bolt. It is generally acceptable to secure the bolt so the lever body will move when forced. This may help prevent damage during a crash. Because the rider's body weight held by the handlebar, not by the brake lever body, it is possible to not have the body fully secure. Generally, begin alignment so the lever body is in line with the rider's arm.

MTB-type Brake Lever Cable Attachment

MTB-type brake lever.

The MTB-type brake cable uses a disc shaped end. The lever will have a fitting in lever for this disc. Typically, begin by lining up a slot in the adjusting barrels.

SRAM® levers feed from the inside through the lever body.

For Shimano® type levers, engage cable end in lever first, the fit into adjusting barrel.

Dropbar or Road Bike Type Brake Levers

The dropbar type lever body often is used by the rider to support his/her weight. This effectively makes the lever similar to a "bar-end" extension. Secure these levers fully. The body should not move, even with the full weight of the user pushing downward.

Shimano® aero-type levers body bolt is on the under rubber hood of the outside of each lever.

Campagnolo® aero-type lever mounting bolts are under the upper outside corner of each rubber hood.

CABLE ATTACHMENT
The brake cable end attaches to the lever by fitting through a socket called the brake cable anchor pivot. Feed the cut end of the wire through the hole in the pivot and out the backside. If the handlebars are taped, it is necessary the housing end be aligned with the cable hole in the lever body. It is sometimes necessary to wiggle the end until you find the housing end.

Campagnolo® brake lever cable installation.

Move brake lever inward as you pull back to expose cable anchor pivot of Shimano® brake/shift levers.

LINEAR PULL BRAKE SERVICE (V-BRAKE TYPE)

How Do I Work on My Linear Pull Brakes?

Useful Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• Hex wrenches (commonly 5mm and 6mm)
• Cable cutter, Park Tool CN-10
• Grease, Park Tool Polylube® 1000
• Light liquid lubricant
• File, or grinder to finish housing ends
• Rags

Service Procedures

Properly adjusted brake systems require attention to small details. This article will begin by discussing the brake lever, inner wire fitting at the lever, and brake housing. Caliper attachment to the frame, pad adjustment to the rim, and pad centering and clearance are then reviewed.

Brake Levers

Brake levers should be positioned so they are easy and comfortable to reach. Loosen the lever mounting bolt and rotated the lever so it is in line with the rider's arm, making it comfortable to reach and use. Re-secure brake lever body. Additionally, brake levers commonly have a setscrew on the lever body that allows the lever to be set closer to the grip. Use reach-setting screw to adjust lever reach according to hand size and riding style.

Cable System

The cable system connects the brake lever to the caliper at the wheel. The brake inner-wire has a fitting on one end, which sits in the lever. Upright bar levers use a round disc shaped end about 7mm (9/32") in diameter.

The brake inner wire end is held by the lever. The common system is shown below. Align the slot in the barrel adjust with the slot in the lever body. Fit the disc into the lever and pivot the wire into the adjustingbarrel. Turn the barrel to hold the inner wire in place.

The Shimano® levers may use a clamp on the lever. Pull this clamp upward, and fit the inner wire disc in place.

The inner-wire passes through a brake housing, which allows the inner-wire to connect from the levers to housing stops on the frame. Housing also allows for bends around corners on the way to the brake caliper.

To determine correct housing length, see How do I cut and size cables and housing?

Calipers and Pads

Linear pull calipers are attached to the frame or fork at the "braze-on". If you are mounting the calipers or have removed them, grease the braze-on before installing the caliper. There may be three different spring hole options, it is typically best to choose the middle hole.

Brake pads are bolted to the caliper arms. When the bolt or nut is loosened, they can be adjustable in several directions. The pad should be correctly adjusted for vertical height alignment, tangent alignment, vertical face alignment and pad toe. Not every brand or model of brake caliper has every adjustment, and sometimes you must simply compromise when setting pads.

Vertical height alignment: This is the setting up and down on the rim-braking surface. View caliper face-on and move the arms, watching the pads move to the rim. For most linear pull calipers, set the pad to the upper edge of the rim-braking surface.

Some linear pull models, such as Shimano® XT and XTR, use a parallelogram movement for the pad, and the pad travels straight to the rim. Set these pads to strike in the middle of the rim-braking surface.

Tangent Alignment

This is the setting of the pad tilt. Viewed pad from the side, the front and back of the pad should be level to the rim. One side should not be higher or lower than the other side. Use care when tightening the pad fixing bolt and hold the brake pad to keep it from twisting.

Vertical face alignment

This is the setting of the pad vertical surface relative to the rim vertical surface. The vertical face of the pad should be set parallel to the face of the braking surface.

Pad Toeing

This is the setting of pad angle as it touches the rim. Toeing refers to setting the pad so the pad's front edge strikes first, which tends to reduce squeal during braking. Caliper arms tend to have play in the pivots and the arms flex when the brake is applied. This may cause squealing in the brake pads. It is simplest to first ride the bike and see if the brakes squeal.

Front of pad strikes rim first for "toe".

Most models of linear pull calipers use a "threaded stud brake pad." Some models use a smooth stud pad with fixing bolt. For the threaded stud types, a threaded bolt is fixed into the pad. The bolt is sandwiched to the caliper arm by a series of convex and concave washers, creating a ball and socket system. The bolt and pad move in the caliper arm for toe and vertical face alignment.

Threaded-stud pads use curved washers to align pad face to rim.

Setting Pads

Before setting pads, begin by double checking that wheel is adequately centered in frame. If wheel is moved from current position, pad alignment will be effected.

1. Loosen pad nut/bolt and lubricate curved washers and thread. Adjust one pad to the rim at a time.
2. If desired, install rubber band shim at back edge of pad. This helps set toe.
   
3. Push caliper arm to rim and view pad alignment. Align pad correctly in four positions.
• Set pad vertical height on rim braking surface.
• Set pad vertical face to be parallel to rim face
• Set front and back edge of pad should be level to rim, so it is tangent to rim.
• If toeing with shim, set so front edge and back edge with rubber band should be touching rim at same time.
4. Tighten pad nut and remove rubber band. Inspect pad alignment again.
5. Repeat alignment of other pad.

Attach inner-wire to brake caliper. Secure wire fixing bolt. Squeeze lever hard several times and set pad clearance at lever for rider preference. If brake feels tight, turn barrel adjuster into lever clockwise to loosen inner-wire tension. If brake feels too lose, turn barrel adjuster counter-clockwise to tighten inner-wire tension. If barrel adjuster is all the way engaged at lever and brake lever still too tight, loosen inner-wire pinch bolt and allow slack to feed through pinch plate. Tighten pinch bolt and test again, doing final adjusting at brake lever barrel adjuster.

Use barrel adjuster to set tightness of pads to rim.

Inspect pad centering to rim. Use set screw on sides of caliper to center pads to rim. Tighten setscrew on arm with pad that is closest to rim. Inspect that pads are not rubbing tire. Re-adjust if necessary. Clean the rim surface and test ride bike.

Use centering screws to move arms and center pads to rim.

Pad Wear

Pads will wear out with use and require replacement. Pads will also harden and become ineffective with age. Pads may also become embedded with aluminum or other contaminants. Inspect and remove as necessary. Pads that are aligned too low on a rim will tend to develop a lip on the low edge. This lip makes correct alignment impossible.

DUAL PIVOT BRAKE SERVICE

Useful Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• Hex wrenches (commonly 5mm and 6mm)
• Grease, Park Tool Polylube® 1000
• Light liquid lubricant
• Bench vise with soft jaws, such as the AV-3
• Hex wrenches
• Metric wrenches, 13mm and 10mm commonly required

Properly adjusted brake systems require attention to small details. This article will discuss caliper arm adjustment, brake attachment to the frame, pad adjustment to the rim, pad centering, and pad clearance. For purposes of this article, the terms "left" and "right" will be from the "mechanic's point of view", not from sitting on the bike.

See also related articles:

• Cable Housing Length
• Shift Lever and Cable Attachment
• Sidepull Caliper Brakes
• Linear Pull and Shimano® V-brake Calipers
• Cantilever Caliper Brakes

This article discusses primarily Shimano® brakes, but the concepts also apply to Campagnolo® and other dual pivot type brakes.

The dual pivot caliper rim brakes are used on many modern road bicycles. It is a combination of a "center-pull" and a "side pull" brake. One caliper arm has its pivot off of wheel center, the other arm pivot directly over the wheel center.

Left side and right side dual pivot brake caliper arms move on separate pivots. Pads move in different arcs as they approach the rim. The left side arm acts as a sidepull. This pad swings downward as it travels toward the rim. As this pad wear thinner, it will travel downward even more. The right side acts as a centerpull. The right pad will travel upward as it approaches the rim. Set the right pad lower on the rim braking surface, and the left pad high on the braking surface.

Pad and Caliper Adjustment

1. Inspect the wheel for centering in the frame/fork. Pad alignment is effected by wheel centering. The image below shows a wheel off to the mechanic's right. Center wheel before adjusting brake.
   

2. Inspect that caliper is approximately centered to wheel (after wheel is centered in frame). Loosen mounting nut and move caliper arms until centered to rim. Re-tighten the mounting nut.
3. Loosen and lubricate threads of pad bolt/nut. Adjust height of right pad to strike upper edge of braking surface. Adjust height of left pad to strike lower edge of braking surface. Most dual pivot pads adjust only for height and tangent. Vertical face and toe alignments are not typically adjustable on dual pivot calipers. Tighten pad-fixing bolts.
   

4. Squeeze lever to test pad clearance. Use barrel adjuster to adjust pad clearance. Set clearance for approximately 3-4mm (1/8 ") per side from pad to rim. Draw slack from system using inner-wire pinch bolt if barrel adjuster is set out to its limit.
5. View pad centering to rim. If right pad appears closer to rim, tighten setscrew. If left pad appears closer, loosen setscrew.
   

6. For Campagnolo® dual pivot type brakes, the centering screw is located on the left caliper arm. See image below.
   

NOTE: It is generally not recommend that dual pivot brakes be bent for "toe". On less expensive brakes with thin caliper arms, it is sometimes possible to bend the arm so the leading edge of the brake contacts the rim first. This can help in reducing brake squeal. If the caliper arms are thicker and stiffer, as with better quality brakes, there is a risk that the caliper arm will snap and break rather than bend. If squeal is a problem in the brake, consider filing the pad so there is a slight gap at the back of the pad.

Pads will wear out with use and require replacement. Pads will also harden and become ineffective with age. Pads may also become embedded with aluminum or other contaminants. Inspect and remove as necessary. Pads that are aligned too low on a rim will tend to develop a lip on the low edge. This lip makes correct alignment impossible.

Some brakes use a brake pad holder. The pad can be removed and a new one installed. The holder will be open in the back and closed in the front. There is often a set screw at the back of the pad holder. Loosen the set screw, and use pliers to pull the back backwards. The new pads are then pushed into the holder. If the fit is tight, a vise with soft-jaws can be used to press the pad into place. Re-install set screw.

Caliper Arm Pivot Adjustment

Because each arm has a separate pivot, each arm pivot is adjusted separately. Neither arm should have play, or a back and forth knocking. Additionally, neither arm should bind as it moves. The caliper arm bridge behind each arm is threaded for each arm pivot bolt. Behind each pivot bolt is a locknut. Dual pivot use a spring to push open the side-pull type arm. A setscrew in the side-pull type arm pushes on the center-pull arm to open it.

Adjustment Procedure

1. To adjust the center pivot of the right arm, begin by removing the brake from the bike.
2. Loosen set screw located under bridge. Not all brands and models use a setscrew on this bridge. Campagnolo® uses a setscrew in the locknut behind the brace.
   
   

3. Release spring tension by un-hooking the spring from the right caliper arm (center-pull type arm). Use care not to damage plastic spring-guide.
   


4. Loosen locknut at base of mounting bolt. It is not necessary to remove locknut. Shimano® typically uses a 12-point 13mm nut. Other brands vary.
   

5. Mount a L-shaped hex wrench vertically in a vise. This will act to hold the pivot bolt and free up your hands.

6. Pivot center pull side inward to expose center bolt. Place brake down on hex wrench. Center bridge is threaded, and can also act as its own lever. Turn brace clockwise slightly (10-15 degrees) to tightened adjustment. Hold brace and fully secure locknut (about 70 inch-pound torque). Test center-pivoting arm for knocking and play. Test arm for adequate free movement. If a rm binds, loosen locknut and loosen bridge slightly. Re-secure locknut and test again. Repeat as needed.
   

7. Move caliper arm to full open position and re-attach return spring. Use care not to damage plastic spring-guide.

8. Mount brake to frame, or use soft jaws in vise to hold mounting bolt.

9. Use hex wrench to hold right-arm adjusting bolt, and loosen locknut on backside of arm. Tighten adjusting bolt slightly. Hold bolt and secure locknut fully. Test for play in arm, and squeeze arm to rim and test for adequate free movement.
   

Mount caliper to bike and adjust pads as described above.

AVID® HYDRAULIC CALIPER BRAKE INSTALLATION & HOSE LENGTH CHANGES

This article will discuss the caliper alignment and adjustments to hose length.

Typical tools and supplies required:

4 and 5mm hex wrench
Rubber gloves, such as MG-1 (recommended)
8mm open end wrench
Avid® compression ring and barbed hose fittings
Clean shop rags, or paper towels
Isopropyl alcohol, or soap and water

Avid® disc calipers are mounted using a cup-and-cone washer system that allows the caliper to adjust to the rotor (Figure 1).

Figure 1
Adjustment washers of Avid® disc calipers.

 

For frame or forks using the common "international standard" mounts (Figure 2), the caliper uses a mounting bracket. The mounting bracket attaches to the frame or fork, and the caliper body attaches to the mounting bracket.

Figure 2
IS mounts (international standard) of suspension fork.

An alternative frame mounting system is the "post type" (Figure 3).   The Avid® caliper bolts directly to the frame or fork posts, with no additional bracket required.

Figure 3
Post-type mounting system of suspension forks.

 

Caliper Alignment

Check that any mounting brackets are secure to the frame or fork mounts. Avid® recommended torque for bracket bolts is 70-80 inch pounds. Loosen the caliper body mounting bolts until body can move freely. Check the caliper is able to move laterally and center over the rotor when adjustment is loose (Figure 4).

Squeeze the lever firmly several times and hold. This should position the caliper pads parallel to the rotor. First snug one and then another caliper body bolt. Next fully secure caliper mounting bolts fully to 40-60 inch pounds.

See related article at Rotor Disc Service.

Figure 4
Check lateral motion before adjusting caliper body.

Hydraulic Hose Length

The Avid® hydraulic brake system uses hydraulic hose (tubing) to connect the brake lever to the caliper. The hose length may be shortened as necessary.   New compression rings and new barbed hose fittings will be required if the hosing is cut.

The length of hydraulic line should be similar to conventional wire brake housing. The housing should be as short as possible without any stressing or pulling on the housing ends. The hose should enter the levers and calipers in a straight line. For the rear brake, rotate the handlebars to test housing length. Housing should be as short as possible without stressing the hose connection to the lever during maximum bar rotation.

1. . Gently pry brake lever boot away from lever body using a plastic lever (Figure 5).

Figure 5
Remove rubber boot from lever body.

2. Loosen hose compression nut counter-clockwise using a 8mm wrench (Figure 6). Slide nut compression nut away from the lever body.

Figure 6
Loosen compression fitting.

3. Pull hose to remove it from the lever body (Figure 7).   Wipe up any fluid spills or drips.

Figure 7

4. Cut the hose to an appropriate length using a cable cutter such as the Park Tool CN-10 (Figure 8). Alternatively, use a razor blade or other sharp tool.   Hose must be cut cleanly and squarely at the end.

Figure 8
Cut hosing end square and clean.

5. Lever boot and compression nut must be in place on hose. Install a new compression ring onto hose.   Thread a new hose-bard into end of hose using a 2.5mm hex wrench (Figure 9).   Push the compression ring close to the new hose-bard at hose end.

Figure 9
Thread hose-barb into hydraulic hose.

 

6. Push the hose end firmly into the lever body to ensure the end of the hose seats into lever (Figure 10). Slide compression nut to lever body.   Thread nut onto body and secure. For steel nuts, secure to 70 inch pounds. For aluminum fitting secure to 47 inch pounds. Push lever boot to cover compression nut.

Figure 10
Install new barbed fitting and compression ring into lever.

7.   Bleed the system anytime it is opened.  

AVID® JUICY CALIPER BRAKE BLEED SERVICE This article will discuss bleeding of the Avid® Juicy disc caliper brakes. For caliper adjustment and housing length adjustments see Avid® Hydraulic Caliper Brake Installation & Hose Length Changes. Typical tools and supplies required: Rubber gloves, such as MG-1 (recommended) T-10 Star Shaped Drive, available on the TWS-2 4mm hex wrench Toe strap or rubber band to hold brake lever Clean shop rags, or paper towels Isopropyl alcohol Bleeding the Avid® System Hydraulic brake systems should be bled anytime the system is opened, such as for shortening the hose. Additionally, the system should be occasionally bled to replace the old fluid with clean new fluid. The Avid® hydraulic disc brake calipers use a DOT 4 or DOT 5.1 fluids. Never use a mineral oil in this system. During any work with DOT fluids, immediately clean any spills on the bike, caliper, or lever with a rag and isopropyl alcohol. DOT hydraulic fluids can potentially damage paint finish.   It is also recommended to wear protective gloves when working with DOT fluids. The Avid® hydraulic brake is best bleed with the Avid® bleed kit, which includes two syringes with special threaded fittings, a bottle of DOT fluid, and a 8mm crow's foot in 3/8" drive. Leave syringe tubing clamps open during storage. Before bleeding, set the volume of the brake system.   Some model brake levers use adjusting knobs at the levers. For the right-hand lever, turn knob completely counterclockwise, then back clockwise one turn. For the left-hand lever, turn knob completely clockwise, then back counter-clockwise one turn. If there is no knob on levers, look for adjustment screw behind lever pivot . Rotate bike as necessary so any air in the hydraulic hose would rise upward from the caliper to the brake lever 1. Prepare one of the two syringes of the Avid® bleed system. Open tubing clamp on the syringe and fill at least half full with DOT 5.1 or DOT 4 fluid. (NOTE: Never use any other fluid such as a mineral oil in a system designed for DOT fluids.) Clamp tubing clip shut and remove gas. Hold syringe vertically and pull slightly on the plunger. This reduces pressure in the fluid, and will cause any significant amount air bubbles to appear (Figure 1). Allow the bubbles to rise, taping the syringe to help dislodge them. Unclamp tubing, and push bubbles out the top. Close clamp and repeat process until fluid appears mostly clear on bubbles. Some tiny bubbles will always be present and will not be a problem in the system. Figure 1 Pull back on plunger to reveal air in fluid. 2. Place a rag under the caliper bleed port to catch any drips. Remove caliper bleed-port screw using a T-10 star-driver (found on the TWS-2 ). Port screw is located in the center of the banjo bolt that attaches the hose to the caliper. Thread syringe fitting into caliper bleed port (Figure 2). Figure 2   3. Rotate brake lever so it points straight to the ground. Remove lever bleed-port plug from lever using a T-10 star-driver (found on the TWS-2). Insert the empty syringe into the lever bleed port and secure (Figure 3). Open hose clamp. The lever syringe will accept the overflow from the rear syringe during the bleeding process. Use a toe strap or thick rubber band to close lever fully to bar or grip. (Note: if lever does not fully bottom against grip, check location of reach adjustment screw. Thread screw so it clears lever body if necessary.) Figure 3 Align lever vertically, attach syringe, and pull lever closed to bar. 4. Loosen brake lever mounting bolt and rotate lever so it points straight to the ground. Remove lever bleed-port plug from lever using a T-10 star-driver. Thread fitting of empty syringe into the lever bleed port and secure (Figure 3). Open hose clamp. The lever syringe will accept the overflow from the full rear syringe during the bleeding process. Closer lever fully to the bar or grip. Use a toe strap or thick rubber band to keep lever closed. (Note: if lever does not fully bottom against grip, check location of reach adjustment screw. Thread screw so it clears lever body if necessary.) 5. At caliper, hold syringe vertical and open tubing clip. Remove any air in the caliper body by first pulling back on plunger gently (Figure 4). Excessive force will cause air to pass by top of plunger seal. Tapping on caliper body with plastic lever will help dislodge air. Let any bubbles rise to the top of the syringe, next to the plunger. Close syringe tubing clamp.   Figure 4 Pull back on plunger to draw any air from the caliper body. 6. Remove strap or rubber from the brake lever. 7. Hold caliper syringe vertical to keep bubbles from entering caliper body. Open syringe tubing clamp and push down on the plunger until plunger end is close to but not touching syringe end (Figure 5).   Do not push bubbles at end of syringe into caliper Figure 5 Push fluid through caliper and out lever. 8. At caliper, close syringe tubing clamp (Figure 6). Remove syringe from caliper and install bleed port screw. Clean up any fluid drips immediately. Figure 6 Close tubing clip at syringe. 9. With the brake lever syringe tubing clamp open and syringe held vertically, draw back on the lever syringe to remove any air from lever body. Tap lever with a plastic lever to help dislodge any bubbles (Figure 7). Squeeze lever repeatedly until no bubbles are seen rising through the tubing. Leave syringe attached and tubing clip open. Figure 7 Pull back on plunger and tap body to free any air inside lever. 10. Rotate the lever to a horizontal position (Figure 8). Unthread syringe from lever body Figure 8 Rotate lever to horizontal and remove syringe. 11. Drip one or two drop of fluid into the lever bleed port screw hole (Figure 9). Figure 9 Drip brake fluid into bleed screw hole. 10. Install bleed port screw in lever and secure (Figure 10). Figure 10 Install and secure bleed set screw in lever. 12. Clean up any spilled or dripped fluid. Test brakes by pulling lever with force. Lever should feel firm and not yield at end of stroke. Check all hose fitting and bleed port screws for leaking. Repeat bleeding procedure if necessary. Discard of fluid a hazardous waste collection facility. 13. Rotate lever back to normal working position and secure.

HAYES® HYDRAULIC BRAKE SERVICE

This article will discuss the service and adjustment of Hayes hydraulic disc brake systems. For information on the disc rotor mounting and service, see Rotor Mounting and Serivce.

If the bicycle frame or fork has the International Standard caliper mounts, use the Hayes mounting bracket. Secure the bracket to the frame mounts and tighten bolts to 110 inch-pounds (12.43 N). If the bike uses the "post mount" system, secure the caliper direclty to the bike.

Loosen the caliper adjusting bolts and install the wheel and rotor. Leave the caliper bolts loose, and squeeze the brake lever. It can be useful to use a strong rubber band to hold lever closed. View the gap in the caliper body for the brake pads. Move caliper body side to side until this gap appears centered to the rotor. Tighten both mounting bracket bolts.

Spin wheel and check for brake rub. If there is rub on the rotor, adjust the caliper as necessary. It can be useful to use a white piece of paper behind the caliper to help sight close tolerances.

Bleeding the System

The Hayes hydraulic brakes use only DOT 3 or DOT 4 brake fluid. Never use a mineral oil for this system.

Begin by rotating the bike and brake levers as necessary so there is an upward flow from the caliper to the lever bleed screw.

Inspect the lever for the bleed screw. Loosen and rotate lever if necessary until screw point upward. The bleed screw of the El Camino model lever faces upward and is the highest point in the system. It is not necessary not rotate the El Camino lever.

Remove bleed screw from brake lever and insert bleed hose fitting. Route bleed hose into bottle to catch fluid. Use rags around lever to prevent fluid from getting on frame or other components. DOT brake fluid tends to be harmful to painted surfaces, and your skin.

 

Remove brake pads from caliper body. Grab post a end of caliper, push it way from body, and pull pad from body.

After pads are removed, push each cylinder into the caliper body. NOTE: Use care not to break post in the center of each piston. Use a box end wrench and push the cylinder into the body.

 

Locate bleed nipple on caliper body. Remove rubber cover from caliper. Attach tubing to end of bleed bottle. Fill bleed bottle with fluid. Attach tubing to bleed nipple. NOTE: It can be helpful to use a small zip tie to hold the tubing to the nipple.

Loosen bleed nipple 1/4 turn. Squeeze bottle firmly for approximately five seconds to force fluid into caliper. Relax bottle to draw any air out of the caliper. Continue to alternate between squeezing bottle for five seconds and releasing bottle until no air bubbles come out of caliper.

When no more air bubble appear in the bottle hose, continue to squeeze the bottle and inspect the exit hose at the lever. Squeeze until the fluid appears clear with no bubbles. Close bleed nipple.

Install and secure the lever bleed screw. Clean all parts with a rag and isopropyl alcohol. Install brake pads into caliper body. Install wheel and rotor and test lever. The lever will feel loose for a few pumps until pistons move to rotor. Lever should feel firm when pulled with force. Inspect all fittings for leaks.

DISC BRAKE MOUNT FACING This article will discuss the use the Park Tool DT-1 Disc Brake Mount Facing Tool. The DT-1 is a precision tool system designed to machine disc brake mounts flat, parallel, and in the same plane.   Use of the DT-1 helps ensure proper disc brake setup and performance. The DT-1 includes everything needed to face the disc brake mounts on frames using 10mm axles and forks using 9mm axles.   It also includes special adapter bushings to allow facing of disc brake mounts on frames using 12mm through axles and forks using 20mm through axles.   Being a precision cutting tool, the DT-1 should be used and stored with extreme care.   Always liberally apply cutting fluid (we recommend Park Tool CF-2 Cutting Fluid) to the brake mount and cutting teeth of the facer during each use. Components should be kept clean and the facing cutter should be periodically wiped with an oily cloth or rust inhibitor before storage, especially in a damp or humid environment.   Store the DT-1 in its original packaging or other safe location.   Like all cutting tools, the facing cutter included with the DT-1 should be periodically replaced or sharpened by a qualified technician. Installation of tool: 135mm Rear Frames: Insert the longer axle into the body of the DT-1. The axle pinch bolt should face to the back. The side of the axle with the C-clip goes to the dropout side. Install the axle fully into frame and secure axle. 135mm frame with 10mm axle. 100mm Forks with 9mm Axles: Insert the shorter axle into the body of the DT-1. The axle pinch bolt should face to the back. The side of the axle with the C-clip goes to the dropout side. Install the axle fully into frame and secure axle. 100mm wide fork, with 9mm axle. 12mm Axle Rear frame: Insert axle through left side dropout, through 12mm ID spacer, and through DT-1 body. Smaller end of spacer fits into body of DT-1. Secure frame axle. Push body of DT-1 to the left until spacer contacts dropout. Secure axle pinch bolt. 12mm rear through axle with DT-1. 20mm Through Axle Forks: Insert axle through side dropout, through body of DT-1 and through 20mm ID spacer. Smaller end of spacer faces left side of fork (disc mount side). Push body of DT-1 to left until spacer contacts dropout. Secure axle pinch bolt. 20mm through axle with spacer. Facing Procedure: Assemble DT-1 into bike as described above. Loosen knob setscrew. Slide knob to end of facing cutter shaft, next to 10mm hex.   Tighten knob setscrew. Loosen pinch bolt and pivot bolt just enough to allow lower body and upper body to pivot and slide on axle. Slide body against retaining ring or bushing. Insert cutter through lower hole of body.   Insert piloted tip of cutter fully into hole of brake mount. Tighten pinch bolt and pivot bolt to lock position. Turn knob clockwise while applying hand pressure to face surface of brake mount.   Remove only enough material to create a clean, flat cut around the face of the mount.   NOTE:   For speed and leverage, a ratcheting wrench with a 10mm socket can be used to turn the 10mm hex head on the cutter . With teeth of cutter contacting face of brake mount, loosen knob setscrew and slide knob on shaft of cutter until contact is made with body.   Tighten setscrew. Pull knob and cutter from lower hole and insert through upper hole. Loosen pinch bolt and/or pivot bolt to fit piloted tip of cutter fully into hole of brake mount, then retighten. Note position of cutter teeth. If cutter teeth contact brake mount and there is gap between knob and body, complete facing and stop. If knob contacts body before cutter teeth contact brake mount, OR, if knob contacts body at the same time cutter teeth contact brake mount, reset the tool as in step 3, and face the upper mount. Use this setting to then face the lower mount. Turn knob clockwise while applying hand pressure to face surface of disc mount.   Continue facing mount until knob stops against body.    The facing process is complete.   The upper and lower mounts should have a clean, flat cut and the faces should be parallel and in the same plane.   Remove DT-1 from frame . NOTES ON DT-1 USE: Like all machining, use a cutting fluid such as Park Tool CF-2. If there is some "chatter" on the surface, the cut will still be square to the axle and the brake will mount properly to the disc. Change the amount of pressure and speed of the cutter to reduce chatter. Use a cutting fluid such as CF-2. When cutting the surface of the disc mount, it is important to achieve a flat surface for the brake mount. In the image below, both mounts are adequately faced. Notice the left and right mount do not look identical. However, if the two mounts were faced to the same reference on the cutter, the job is done. Adequately machined calilper mounts. It is important to note the "foot print" left by the cutter and compare this to the "foot print" or contact area of the caliper body or caliper body bracket adapter. Some mounts require significant machining, and the size of the machined surface may be smaller than the bracket. The adapter bracket above will have a larger contact area then the machined surface. Use spacers in this casee. Close up of a machined cut likely to need spacing. Spacers in place for the adapter bracket. If the caliper mount is equal to or smaller than the machined area, no spacer is required. This disc mount-to-caliper interface will not require a spacer.

HOUSING LENGTH

Typical Tools and Supplies

• Cable Cutter:CN-10
• Brake housing and cables as needed
• Shift housing (compressionless) and cables as needed
• Housing end caps (ferrules) as needed
• Light lubricant
• Mill file (for brake housing as needed). Bench grinder or dermel also useable.
• Hex wrenches for cable binder bolts

This article will discuss the cutting and sizing of both brake and derailleur housing. See also related articles on shift levers or brake levers.

The Park Tool CN-10 Cable Cutter is designed to cut multi-strand wires such as gear and brake cable, brake housing, and compressionless gear housing. Compressionless shift housing uses many inner support wires running longitudinally with the inner plastic liner. Compressionless shift housing is intended for shifting systems only, not braking. Brake housing is commonly made of a wire wound around a plastic liner. Use ends caps or ferules at the ends of housing when ever possible. There is also available a woven or braided-type of housing that is may be used for both brake housing and shift housing. It is recommended to lubricate inside the housing or the cable is installed.

The jaws of the cable cutter surround and then shear the material. Using plain diagonal cutters can simply flatten and smash cables. As with all cutting tools, it is recommended to wear eye protection.

Grab and hold the cable or housing close to the jaws. Use care not to cut your fingers. Hold cable or housing perpendicular to jaws and squeeze levers quickly for a clean cut, as seen below.

After cutting the compressionless gear housing, inspect the end to see if it flattened a bit. Use the crimper section of the CN-10 to open up the housing and inner liner before installing an end cap and cable. You can also use the crimper section cutter to crimp on a cable end cap, as seen below.

How Long Should Housing Be?

Brake and gear housing allows the cable wire to be routed around bends and connects the levers to the frame stops. The less the drag on the cables, the better for the shifting and braking. Too short of housing will cause it to kink and bind, making even more friction. As a rule of thumb, try to size the housing so it is as short as possible but it still enters the stops and barrel adjusters in a straight approach. For the rear derailleur housing, note especially how the housing enters the barrel adjuster.

In the left image above, the housing bends immediately upon leaving the barrel adjuster. This can actually bend the housing end cap. The image to the right shows how longer housing in this case allows the housing to enter straight.

The left image above is a typical new bike housing length. The housing bends and kinks as it enters the barrel adjuster. The image to the right shows longer housing allowing a straight entry into the barrel adjuster.

The image above shows brake and shift housing which is much too long. The housing could be shortened and still have a smooth, straight approach to the levers and housing stops.

The routing of housing may affect the length. Typically the front derailleur shift housing is run on the left side of the frame, while the rear derailleur shift housing is run on the right. This may at time cause unnecessary bending in the housing. In some cases, it is possible to "cross over" the housing, running the front shifter to the right side stop, and the rear shifter to the left side stop. It will then be necessary to again cross the cable. Consider this option, but if the cable ends up rubbing the frame, it is not a good idea. There may be some light rubbing between cables, but this would result in less friction than poorly routed housing.

Shift lever housing that is too long. Housing passes center line of bike, then must bend back to housing stops.

Shift housing is crossed over at headtube, and crossed again on downtube. Arc of housing is much smoother than black housing in example of too long housing.

Cutting Brake Housing

Brake housing is typically made of single strand flat wire wrapped around an inner plastic tube. This housing may be cut with the CN-10, or diagonal cutting pliers. Because of the design of the housing wire, it is not always possible to get a flat, clean cut. It is best to finish any burr with a file. Lightly grinding the end will also improve the housing and reduce friction.NOTE: Compressionless housing does not require finishing.

ROTOR DISC SERVICE AND INSTALLATION

This article will discuss disc brake rotor installation and serivce.

Disc caliper brakes slow the bike by converting the speed and energy of the bicycle into heat. The system can generate significant heat from slowing the wheel and bike. Allow rotor and caliper to cool before touching or servicing.

The rotor diameter may vary between models and brands. Common rotor diameter sizes are 145mm, 152mm, 160mm, 185mm, and 203mm. The brake caliper, bike frame, and rotor diameter must be compatible.

The rotor or disc of the disc brake system secures to a disc-specific hub. The common system uses six bolts. Many brands use rotor bolts requiring the use of a 12-point star shaped driver such as the Park Tool PH-T25, or Torx® driver. A mild thread locker is recommended on the bolts. Secure rotor bolts to manufacturer's torque specifications, typically between 40 and 60 inch-pounds.

Some Shimano® rotors use a splined fitting system with a lockring, similar to a cassette lockring. The spline system of the rotor matches splines at the hub. Use the Park Tool FR-5 to secure the lockring to 350 inch-pounds. The Shimano® Saint and Hope rotors require a specially sized Shimano® tool.

The rotor and brake pads should be kept clean of oils and grease. If pads become contaminated, it is best to replace them. When cleaning the rotors or washing the bike, remove wheel and remove pads from bike. Use isopropyl alcohol or similar solvent when cleaning rotor surface of dirt or film. Do not use a solvent or cleaner that contains oils or leaves an oily residue.

Rotors may become bent or warped with use and abuse. Some re-bending may be possible, but rotor replacement is typically the best option. The Park Tool DT-2 Rotor Truing Fork allows you to subtly bend and align the rotor. Watch the wobble at the caliper. Place the long section of the DT-2 over the rotor and pull or push as appropriate. It only takes a small amount of effort to move the rotor. Sight rotor and re-bend as needed.

It is also possible to bend the rotor at the rotor arms. This is useful when there is long bend at the rotor perimiter. Use the short opening in the DT-2. It allows the tool to be at a 90-degree offset to the rotor face.

The DT-3 Rotor Truing Gauge will help speed the sighting and correcting of the rotor alignment. The DT-3 mounts to the TS-2 truing stand. Mount a wheel in the truing stand, with rotor facing the DT-3. Align the moveable gauge to the outer perimeter of the rotor and spin the wheel. Move the gauge end close to the rotor face and note any rotor movement, similar to truing a wheel with a truing stand.

The DT-3 can be fitted with a dial indicator, the DT-3i Dial Indicator Kit. The DT-3i magnifies the run-out, allowing subtle bends in the rotor to be easily located.   The DT-3i reads in increments of .01 mm and uses a "balanced face", reading both clockwise and counterclockwise from "0."

Mount the DT-3i to the end of the DT-3. Rotate the dial as necessary to allow viewing of the face. Back the threaded gauge away from the rotor. The DT-3i plunger end will contact the rotor. Use the quick release of the DT-3 to move the plunger of DT-3i to the outer perimeter of the rotor. Continue to press the DT-3i into the rotor to compress the plunger a few millimeters. Secure quick release skewer.

Slowly rotate the wheel and note movement of needle on dial. Locate a section of rotor that is true, with relatively little movement. This section will serve as the "0" reference point for sections requireing truing. Loosen the dial face locking knob and move the rotor face of the dial indicator until the needle lines up with "0."

Spin the wheel and note any movement away from the the zero mark. Use the DT-2 to align the rotor. The DT-3i will then show relatively movement off the zero mark.

AVID® MECHANICAL DISC ADJUSTMENT

This article will discuss the service and adjustment of the Avid® mechanical brake systems. For information on the disc rotor mounting and service, see Rotor Mounting and Serivce.

Disc brake systems use a caliper mounted near the dropouts of the frame or fork ends, and a rotor (disc) mounted to the hub. The brake pads are housed in the caliper and are forced into the rotor. Disc caliper brakes slow the bike by converting the speed and energy of the bicycle into heat. Disc brakes can be effective in wet weather where mud, dirt and water are a concern in braking. The system can generate significant heat from slowing the wheel and bike. Allow rotor and caliper to cool before touching or servicing.

Mechanical disc brake systems use calipers that are cable actuated, similar to rim caliper brakes, with an inner brake wire and housing pulled by a brake lever.

Disc brake calipers mount to fittings on the bicycle frame and fork. The common standard is referred to as the International Standard. This standard uses two mounting holes spaced 51mm apart and the caliper mounting bolts are positioned perpendicular to the rotor face. A less common mounting system is the post mount. The mounting bolts of the post mount are parallel with the rotor faceand the mounting holes are spaced 74mm apart. Brake calipers designed for the post mounting system can be fitted with adapters to work with the International Standard.Brake pads for both mechanical and hydraulic systems are available in various compounds. Generally, a softer resin material will tend to squeal less. It will also offer the user more modulation, or the ability to brake lightly. However these types of pads will also wear more quickly. The harder metal or semi-metallic pads will last longer, especially in wet and muddy conditions

The rotor or disc of the disc brake system secures to a disc-specific hub. The common system uses six bolts. Use a mild thread locker on the threads, and secure the bolts. Many brands use rotor bolts requiring the use of a Torx T-25 wrench. A Torx fitting is a special 12-point socket head bolt. Secure rotor bolts to manufacturer's torque specifications .

Mechanical Disc Brakes

Mechanical disc calipers use two brake pads, one on each side of the rotor. Depending upon the design of the caliper, both pads may move to contact the rotor. However, alternative designs have one pad being fixed, with only one pad moving to contact the rotor. With this design, the rotor will flex to push against the fixed pad when the brake is used.

Flat handlebar brake levers used with mechanical disc calipers are compatible with the linear pull caliper rim brakes. The lever should be set for a comfortable reach and secured to the bar. The brake housing and brake wire are the same as with rim caliper brakes. Prepare housing and wires as with rim caliper brakes.

Avid® Brake Caliper Adjustment

Avid® mechanical calipers use an outer pad that moves toward the rotor when the caliper-actuating arm is pulled by the brake wire. The inner pad can be adjusted toward or away from the rotor with a pad-adjusting knob, but it is fixed during braking. The moving pad flexes the rotor toward the fixed pad when the brake is operated. The moving pad also uses an adjusting knob to position the pad relative to the rotor. The dial uses an indent system, with 16 per revolution. One complete revolution moves the pad approximately 1mm.

The Avid® mechanical disc brake for MTB bikes uses a brake lever designed for linear pull brakes. Pad adjusting knob moves pad position relative to rotor. Avid® disc caliper brakes use a ball-and-socket system for the caliper mounting bolts. This fixing system is similar to many brake pads on linear pull caliper rim brakes. This system allows easy alignment of the brake caliper to the rotor.

The caliper body position over the rotor is very important to braking performance. Compare the gap from the rotor to the caliper. The gap from the caliper body to the rotor on the inside (fixed pad side) should be approximately twice as much as the gap from the caliper body to the rotor on the outside.

The procedure for Avid® mechanical caliper pad alignment is as follows:

1. If the caliper is attached to a bracket, check that the bracket is fully secured to the frame or fork.
2. Loosen caliper-mounting bolts so caliper is loose on bracket. Caliper adjustment is made at caliper to bracket interface, not at bracket to frame/fork interface.
3. Loosen brake wire pinch bolt if it is secured.
4. Check that both pad adjusting knob dials are turned fully counter-clockwise to move pads fully away from rotor.
5. Turn the inner pad adjusting knob clockwise approximately 1 turn (about 24 "clicks').
6. Turn the outer pad adjusting knob clockwise until pad fully secures rotor. This aligns pads and caliper body to rotor.
7. Snug each caliper mounting bolt. Then alternatively tighten first one bolt, and then the other until both are fully secure.
8. Draw slack from the brake wire and secure pinch bolt. Do not allow caliper arm to move upward when drawing slack from brake.
   
   
   
   
9. Set pad clearance. Inner pad (fixed pad) should have twice the gap to the rotor as the outer pad (moving pad). Loosen fixed (inner) pad adjusting knob 2-3 clicks counter-clockwise. Loosen moving pad adjusting knob 4-6 clicks counter-clockwise.
10. Squeeze lever to test caliper brake. Adjust lever modulation setting by moving pads inward or outward from rotor by using both pad adjusting knobs.

To maintain the 2:1 ratio, turn the fixed pad adjusting knob twice as many clicks as the moving pad adjusting knob. For example, if a looser modulation is desired, turn the fixed pad adjusting knob counter-clockwise 4 clicks, and the moving pad adjusting knob counter-clockwise only 2 clicks. The caliper actuating arm is designed to operate from a fully open position. Set cable tension at the adjusting barrel so actuating arm is fully opened or returned.

Avid® Mechanical Brake Pad Removal and Replacement

As the bike is ridden and the pads wear, do not use the brake lever adjusting barrel or cable pinch bolt to account for pad wear. Caliper arm may bottom out on caliper body, preventing pads from pressing on rotor. Use pad-adjusting knobs to move pads closer to rotor. Turn the fixed pad adjusting knob clockwise twice as many clicks as the moving pad adjusting knob to maintain the 1:2 ratio of pad to rotor spacing. For example, if the fixed pad adjusting knob is turned clockwise two clicks, turn the moving pad adjusting knob one click.

Avid® mechanical brake pads should be removed and replaced if the pad thickness, including the metal holder, is less than 3mm.

The procedure for Avid® mechanical caliper pad removal and replacement is as follows:

1. Mount bike in repair stand and remove the wheel.
2. Loosen each pad adjustment knob an equal amount.
3. Grab lever at end of pad and push toward center of caliper body, pulling pad outward and away from caliper. Repeat process for second pad.
   
   
   
   
4. Push lever to center of caliper body and lift to remove. Note orientation of pad return spring and remove spring from pads.
5. Place new pads over pad return spring. Spring should be sandwiched between new pads. Installation lever is set asymmetrically on pad.
   
   
   
   
6. Align bridge of spring with caliper boss locators. Gently squeeze return spring and pads. Engage pads into caliper body. Pad installation lever orients away from brace bolts. Push return-spring and pads into place. Pad locator will engage bosses in caliper boss.
   
   
   
   
7. Push pads into caliper body.
8. Install wheel.

SHIMANO® HYDRAULIC BRAKE SERVICE AND ADJUSTMENT

This article will discuss the service and adjustment of the Shimano® hydraulic disc brake systems. For information on the disc rotor mounting and service, see Rotor Mounting and Serivce.

Disc brake systems use a caliper mounted near the dropouts of the frame or fork ends, and a rotor (disc) mounted to the hub. Hydraulic systems use sealed tubing to push brake fluid. The brake pads are housed in the caliper and are forced into the rotor.

Disc brake calipers mount to fittings on the compatible bicycle frame and fork. The common mounting standard is referred to as the International Standard. This standard uses two mounting holes spaced 51mm apart and the caliper mounting bolts are positioned perpendicular to the rotor face. A less common mounting system is the post mount. The mounting bolts of the post mount are parallel with the rotor faceand the mounting holes are spaced 74mm apart. Brake calipers designed for the post mounting system can be fitted with adapters to work with the International Standard. Brake pads for both mechanical and hydraulic systems are available in various compounds. Generally, a softer resin material will tend to squeal less. It will also offer the user more modulation, or the ability to brake lightly. However these types of pads will also wear more quickly. The harder metal or semi-metallic pads will last longer, especially in wet and muddy conditions.

Hydraulic Disc Brakes

Hydraulic brake systems use a piston at the hand lever called the "master' piston. The piston pushes brake fluid through sealed brake tubing to another set of pistons at the caliper called the "slave" pistons. The slave pistons push the pads to the rotor. Because the hydraulic fluid does not compress or flex, hydraulic systems are considered higher performance than mechanical systems.

With use over time, brake fluid will become contaminated with dirt and moisture and should be replaced. It is critical to use the correct type of fluid for the specific brake. Some manufacturers use mineral oil as the fluid, while others use an automotive brake fluid. The manufacturer will specify the type of fluid. The different types of brake fluid should never be mixed. Using the wrong fluid is likely to cause seals to fail, resulting in brake failure.Automotive fluids are DOT (Department of Transportation) approved and are generally polyglycol fluids. The D.O.T. fluids have different ratings, such as 3 or 4. Contact the manufacturer for a specific recommendation. Automotive brake fluids are caustic and toxic. Work with care to avoid fluid contact with the outside of the lever or caliper, the bike, or your skin. Use of protective gloves, such as MG-1 Mechanic Gloves is recommended.

Hydraulic systems should be inspected at all fittings and hose connections for fluid leakage and seepage. Additionally, the bike should not be stored or turned upside down, as air may enter the brake lines. If the bike has been upside down, allow it to sit several minutes before use, and test the levers by pulling with force.

The hydraulic brake lever is positioned on the handlebar similar to conventional or non-hydraulic levers. Set the angle for comfortable reach when the cyclist is in the saddle. The brake lever reach is adjusted behind the lever pivot. Tightening the screw moves the lever closer to the handlebars.

Brake manufacturers design the hydraulic cylinders at the calipers to be compatible with the cylinder at the brake lever. The diameter of the cylinder and the distance it will move (the stroke) may vary between brands. Check with the manufacturer before mixing different levers and calipers. As the brake fluid heats, it expands. Hydraulic disc systems use a reservoir system that contains a bladder to allow for the expansion of the brake fluid. Some models use an enclosed bladder in the lever, while others use an "open system."

The master piston is sealed when the lever is pulled, but is open to the reservoir when the lever in fully open. In all hydraulic systems, it is important that there is no air in the tubing or lines between the caliper and the lever piston. Air bubbles in the line will compress, causing the brake to feel "soft" when the lever is pulled with force.

For any disc system, it can be difficult to view the pad to rotor alignment. Place a white paper or white rag behind the area you are viewing. If possible, shine a flashlight on the rag for a highlighted background.

There are two different caliper mounting systems for the Shimano® hydraulic brake caliper. The caliper body may bolt directly to the rotor mounts of the frame or fork.

Alternatively, the caliper body may bolt to a bracket, and the bracket is bolted to the frame or fork. If the brake caliper is bolted directly to the mounts, it is necessary to use thin washers and shims to adjust the caliper. A washer with a post, called a "banjo washer" can be placed between the frame or fork mount and the caliper body. Install washers and secure mounting bolt. View pad to rotor alignment, then add or subtract washers as necessary.

Hydraulic systems have very close tolerances between pads and rotor. Alignment of the caliper to the rotor is critical to the performance of the brake. The procedure for Shiman® Hydraulic XTR, XT, Deore, Saint caliper alignment using an adaptor bracket is as follows:

1. For bracket mounted calipers, fully loosen caliper mounting bolts. This will allow the caliper to move sideways.
2. Depress the brake lever to secure pads against the rotor and maintain pressure. This will move caliper so pads are aligned to rotor.
3. Inspect caliper and brake pad pistons. Push caliper left or right until pistons appear centered over rotor.
4. Maintain pressure on the rotor and tighten the caliper mounting bolts.

   

5. Release lever and inspect this initial pad alignment. Ideally, the pads should clear the rotor with no rubbing. In some cases, however, a light rubbing may occur and will not generally be an issue with performance. If the wheel seems to slow when it is turned, re-adjust the pads by loosening the caliper mounting bolts to reposition the caliper.
6. Fine-tune the pad alignment by fully loosening one mounting bolt while keeping the other bolt snug. This will allow you to push the caliper while pivoting off the snug bolt.

If the brake caliper is bolted directly to the mounts, it is necessary to use thin washers and shims to adjust the caliper. A washer with a post, called a "banjo washer" can be placed between the frame or fork mount and the caliper body.

Install washers and secure mounting bolt. View pad to rotor alignment, then add or subtract washers as necessary.

Brake Pad Removal and Replacement

Brake pads wear thin with use. Most manufacturers list specifications for minimum pad thickness. For Shimano® pads, replace when pad material (not including pad holder) is less then 0.9mm thick. Inspect old pads when removing. If pads are worn unevenly, it may be a sign that the caliper is misaligned to the rotor.

New disc pads may require a "burn in" period. Solvents from manufacturing are burned off from the heat of braking. Braking performance will improve after the burn in period.

As the pads wear, the pistons reposition closer to the rotor. It will be necessary to remove the rotor and push the pistons away from the center before installing new pads. The procedure for Shimano® XTR, XT, Deore, Saint pad replacement is as follows:

1. Mount bike in repair stand and remove wheel(s).
2. Rotate lever on handlebar until top surface of reservoir is parallel with the ground.
3. Clean lever of dirt and wipe around reservoir cover. Remove reservoir cover. This will allow excess fluid to spill from reservoir.
4. Remove pad fixing bolt clip and unscrew pad fixing bolt.

   

5. Remove pads by pushing them outward, away from hub axle. Notice orientation of pad return spring between pads. This spring assists pad release from rotor during braking.
6. Wipe piston area clean. Use a clean rag and a mild solvent such as isopropyl alcohol to clean the piston faces and inside the caliper body.
7. Using a plastic lever, such as a tire lever, push both pistons into the caliper body. Push near center of piston and avoid pushing edge of piston.

   

8. Push pistons back into caliper body.
9. Place pad return spring between new pads. Pad return spring is placed between pads.
10. Install pads into caliper. Orient eyehole in pads and spring to align with pad fixing bolt hole.
11. Install and secure pad fixing bolt.
12. Install reservoir cover and secure screws.
13. Install wheel and test brake by squeezing lever with force. If lever feels soft, system will require bleeding. If pads drag or are misaligned, reset the pads.

Brake Fluid Bleeding & Replacement

Bleeding a hydraulic system is removing trapped air from the lines and calipers. Shimano brake systems use mineral oil. Never use an automotive D.O.T. brake fluid in a system requiring mineral oil. Remove the brake pads before bleeding or replacing fluid so they do not become contaminated with brake fluid. When servicing hydraulic brakes, work in clean condition. Use care to keeps hydraulic pieces, such as the bladder, clean and away from dirt.

The procedure for bleeding Shimano® XTR, XT, Deore, Saint brake fluid is as follows:

1. Mount bike in repair stand. Remove wheels.
2. Remove brake pads to avoid contamination by brake fluid.
3. Install Shimano® brake block #Y8CL18000 in place of pads. If blocks are not available, substitute a block of about 10mm wide block to prevent piston from extending. Substitute a clean 10mm hex wrench if the brake block is not available.

   

4. Rotate bike as necessary until tubing has a continuous upward slope from the brake caliper to the reservoir. Rotate lever on handlebar until top surface of reservoir is parallel with the ground.
5. Attach bleed tubing to end of bleed nipple at caliper. Attach plastic bag to end of tubing to catch waste fluid .

   

6. Clean dirt from lever and wipe around reservoir tank cover. Unthread screws at reservoir tank cap.
7. Remove reservoir cap and bladder. Fill reservoir to top.
8. Loosen bleed nipple, at caliper body, 1 turn.
9. Operate lever repeatedly. Bubbles will appear in reservoir tank, and fluid level may drop. Keep reservoir filled with fluid. Use a non-metallic lever to tap along brake line to encourage any air trapped in the line to rise toward the reservoir.
10. Keep reservoir tank filled with fluid. When oil begins to come out of bleed tube, close bleed nipple at caliper body.
11. Test lever by pulling. Lever will eventually become stiff and firm when pulled. If there is no resistance to lever, open bleed screw and continue to operate handle and pump oil into the system.
12. When lever resistance stiffens, close bleed nipple. Hold lever closed and maintain pressure.

    

13. Using a 7mm wrench, or a small adjustable wrench, loosen bleed nipple to open system. Open and close system within one second, noticing if any of the expelled fluid contains air bubble.

    

14. Open system briefly to expel air bubbles
15. Release lever. Check reservoir tank and add fluid.
16. Operate lever repeatedly. If lever feels stiff with resistance at the end of its travel, line contains no air and is fully bled.
17. If lever feels soft, repeat steps shimanodisc10 through YY.
18. Check that reservoir tank is filled to top. Install reservoir bladder and cap. Expect some excess fluid to spill from lever. This is normal and insures no air is below bladder. Tighten cap screws.
19. After bleeding, disconnect hose from bleed nipple. Wipe lever and caliper of any fluid.

Brake fluid can become dirty with use and may become contaminated with moisture. If the bike is used extensively, the fluid should be replaced once a year. The procedure for changing fluid is as follows:

1. Proceed with steps xx through yy above.
2. Operate lever to pump fluid through the hose, adding more fluid as level in reservoir tank drops. Continue to pump lever until fluid appears clear at the bleed hose. Again, check fluid and add as the level drops at the reservoir tank.
3. Close nipple and proceed with the bleeding process above.

Resetting Brake Pads

If the pads seem to rub on the rotor, and re-alignment will not prevent this, the pistons may need to be reset. The procedure requires the use of a shim in the caliper for the adjustment. Shimano® supplies this shim, part #Y8CL1200, with the brake set when purchased new. Alternatively, use a hard, flat material that is the thickness of the rotor. Park Tool cone wrenches, such as the Double-Ended Cone Wrench DCW 1-4, match the width of rotors and can substitute for the pad spacer.

The procedure for resetting Shimano® XTR, XT, Deore, Saint pads is as follows:

1. Mount bike in repair stand. Remove wheel(s) from bike.
2. Remove pad retention screw and remove pads. Use a clean rag and a mild solvent such as isopropyl alcohol to wipe clean the piston faces and inside the caliper body.
3. Use a plastic lever, such as a tire lever. Push each piston back into caliper body. Notice if the piston moves after being positioned back into caliper body. If a piston moves after being reset, there may be excess fluid in the system.
4. Remove cover of reservoir. Allow excess fluid to spill out of the reservoir as the pistons are pushed into the caliper body. If reservoir cap was removed, re-install cap. Wipe oil from lever.
5. Install pads, pad return spring, and pad retention screw.
6. Install floating shim (Shimano part number Y8CL1200) or a shim of equivalent thickness.

   

7. Squeeze lever repeatedly. Pistons will automatically center to caliper body.
8. For bracket mounted caliper bodies, loosen caliper mounting bolts fully.
9. Install wheel. DO NOT squeeze lever at this time.
10. Inspect pad alignment to rotor. For bracket mounted caliper bodies, position caliper body to center pads over rotor. Tighten caliper mounting bolts and inspect.
11. For caliper bodies mounting directly to the frame, use washers to center pads to rotor. Secure mounting bolts fully.
12. Squeeze lever and inspect pad alignment. Fine tune pad alignment as necessary.

SIDEPULL BRAKE SERVICE

Useful Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• Hex wrenches
• Light liquid lubricant
• Bench vise with soft jaws, such as the AV-1
• Brake wrenches such as OBW and CBW
• Metric wrenches, 13mm and 10mm commonly required

Properly adjusted brake systems require attention to small details. This article will discuss sidepull caliper arm adjustment, pad adjustment to the rim, pad centering, and pad clearance. For purposes of this article, the terms "left" and "right" will be from the "mechanic's point of view", not from sitting on the bike.

See also related articles:

• Cable Housing Length
• Shift Lever and Cable Attachment
• Dual Pivot Caliper Brakes
• Linear Pull and Shimano® V-brake Calipers
• Cantilever Caliper Brakes

The side pull caliper rim brakes were once the common road bike brake. Both caliper arms share a single pivot, which is centered over the wheel. The image above shows modern dual pivot, and centerpull brake calipers, and sidepull. Sidepull calipers are also found on some BMX, Freestyle, and some recreational bikes.

Both brake pads move downward on an arc as they approach the rim. As the pads wear thinner, they will travel downward even more. Generally for side pull, adjust pads to the top of the rim braking surface, but not so high they would strike the tire. See image below.

Pad and Caliper adjustment

1. Inspect the wheel for adequate centering in the frame/fork. Correct as necessary.
2. Loosen and lubricate threads of pad fixing bolt/nut. Adjust pads so they strike strike upper edge of braking surface, but not the tire.
   

3. Check front end and back end of pad. The pad should be square or tangent rim.
   

4. Tighten pad-fixing bolts.
5. Attach cable (if necessary). Squeeze lever to test pad clearance. Use barrel adjuster to adjust pad clearance. Set clearance as desired. Draw slack from system using inner-wire pinch bolt if barrel adjuster is set out to its limit.
6. View pad centering to rim. If pads are off-center, manipulate center pivot bolt. There are different procedures possible.

• Some models use a flat machined into the center stud. Use the Park Tool OBW Offset Brake Tool or a cone wrench to grab this flat. Place a wrench on the mounting nut behind the brake. Move both wrenches the same direction and same amount to move the pivot. In the image below the wrenches are rotated counter-clockwise from our view, which moves the caliper arms counter-clockwise arond the pivot bolt.
  
  

• Saftey pivot types have the pivot bolt head in front of the caliper arms. Use a wrench on the mounting nut and a wrench on the bolt head. DO NOT use the nuts behind the calipers arms as centering flats.
  

• If the brake is a double nut type, and has no centering flat, it may accept the OBW-3 spanner. Use the OBW-3 to grab the spring and move the pivot. It may also be necessary to loosen mounting bolt and move brake to center, hold it by hand and re-secure mounting nut.
  
  

NOTE: It is not critical or even important that brake pads strike the rim at the same time. It is possible for one pad to reach the rim first. The rim will not be pushed to the side because the pivot of the brake arms is above the wheel. The other pad will eventually strike the rim and the pads will then squeeze the braking surface to slow the bike.

Squealing is the result of a harmonic resonance from a slip-and-stick phenomenon, similar to how a violin bow resonates on a string. The brake pads grab the rim and are pulled forward by the force of the wheel. The arms must at sometimes jerk backwards, but if you are still braking, the arms are flexed forward again. This is repeated again and again many times per second, and this creates the squeal. Because of this, flexible and less expensive arms tend to squeal more than stiff calipers of better brakes. It is possible to reduce squeal by having the leading edge of the brake pad strike first. This tends to reduce the back and forth jerking of the arms.

Some brake caliper arms can be toed. Toeing can be achieved in some cases by bending the caliper arm slightly using the Park Tool BT-3. It is best to use two BT-3 tools at the same time. This will minimize stress on the center pivot. Begin with a slight gap at the back of the pads and test the bike before adding toe. An option to toeing is to file the pads so the leading edge strikes first.

Pads will wear out with use and require replacement. Pads will also harden and become ineffective with age. Pads may also become embedded with aluminum or other contaminants. Inspect and remove as necessary. Pads that are aligned too low on a rim will tend to develop a lip on the low edge. This lip makes correct alignment impossible.

Sidepull Caliper Arm Adjustment

The caliper arms pivot off the center bolt or stud. The arms should open fully when squeezed, but should have no play or knocking. There are two basic types of sidepull caliper designs. The double nut type has two nuts in front of the caliper arms. The inner nut is the adjustment nut and is locked in place by the outer locknut. The other design type was commonly used by Shimano® and is called the "safety pivot". In this design, there the adjusting nut and locknut are behind the brake arms. The brake must be completely removed from the bike to have the caliper arm movement adjusted. The adjusting nut doubles as a the spring holding nut.

Double Nut Adjustments

The double nut types can be adjusted with the caliper mounted to the bike. Check arms for play by grabbing each arm and moving back and forth along the axis of the pivot. If there is no play and the calipers open when gently squeezed, the pivot adjustment is adequate.

If there is play, the adjustment should be tightened. Hold the adjusting nut secure with a thin wrench, such as the CBW or OBW wrench. Note position of wrench. Loosen locknut with a second wrench, and move adjusting nut slightly clockwise. Hold adjusting nut and secure locknut fully.

Repeat check of caliper arms for play. Repeat as necessary until play is gone and brake open upon gentle squeezing. If arms will not fully open when gently squeezed, the adjustment may be too tight. Try to adjust looser a very slight amount. With much use the spring may become fatigued and a good setting is not possible. Replace spring if necessary.

Saftey Pivot Type

Safety pivot caliper arm mount to a single bolt. Below the caliper arms shown apart on the pivot bolt.

The locknut and adjusting nuts for the safety-pivot types is located behind the caliper arms. The brake must be removed from the bike to access these nuts. The spring must also be disengaged and flipped back out of the way. Use care not to damage plastic spring carriers, if any.

It is easiest to work with the brake in a vise using soft jaws such as the AV-3. If the brake has a 12-point locknut, place the box end of a wrench over the nut, and then grab with the vise. The adjusting nut also holds the spring, which can make the adjustment awkward. Hold the adjusting nut with a thin wrench such as the OBW wrench, and loosen the locknut.

Tighten adjusting nut, turning it toward bolt head, only slightly. Hold adjusting nut and secure locknut fully. Test for play, and repeat adjustment if play if felt.

To test final adjustment, flip spring back into place and attach spring to arms. Squeeze gently and release. Re-adjust as necessary.

CANTILEVER BRAKE SERVICE

How Do I Work on my Cantilever Caliper Brakes?

Useful Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• Hex wrenches (commonly 5mm)
• Cable cutter, Park Tool CN-10
• Metric wrench, commonly 10mm CBW-1
• Grease PPL-1
• Rags

Service Procedures

Properly adjusted brake systems require attention to small details. This article will begin by discussing the brake lever, inner wire fitting at the lever, and brake housing. Caliper attachment to the frame, pad adjustment to the rim, and pad centering and clearance are then reviewed. See also related articles:

• Brake and gear lever cable attachment
• Housing and cable sizing

The cantilever caliper rim brake was once common on MTB bikes, but has been replaced in popularity by a similar brake, the "Linear Pull" type. Cantilever calipers attach to separate frame pivots on either side of the wheel. The inner-wire attaches to a carrier piece located above the tire. The carrier is pulled upward causing the caliper arms to swing inward.

Hand Lever Position

Cantilever rim brakes rely on hand pressure at the brake levers being transferred to the brake pads and the rim. Begin any adjustments by making sure the brake levers are positioned so they are easy and comfortable to reach. Rotate the lever so it is in line with the rider 's arm, making it comfortable to reach and use.

Lever Reach

MTB levers commonly have a setscrew on the lever body that allows the lever to be set closer to the grip. The lever reach can then be set according to the rider 's hand size and riding style. Tighten the reach setscrews and bring the levers toward the grip to accommodate smaller hands or shorter fingers.

Cable System

The cable system connects the brake lever to the caliper at the wheel. The brake inner-wire has a fitting on one end, which sits in the lever. Upright bar levers use a round disc shaped end about 7mm in diameter.

The inner-wire passes through brake housing, which allows the inner-wire to connect from the levers to housing stops on the frame. Housing also allows for bends around corners on the way to the brake caliper. Housing should be neither too long nor too short. For more detail on brake housing and housing length, see Sizing Brake and Gear Housing

Caliper Attachment

Cantilever caliper arms are attached to the frame or fork at the "braze-on". The braze-on is a 8mm diameter, 16mm long stud fitted to the frame.

Some models of cantilevers have removable return springs. Each side uses a different coil spring direction. If springs are reversed, they may become damaged, and the brake will not operate properly. As seen from the mechanics view (as in the image below), the right caliper arm uses a right-hand coiled spring. The left caliper arm uses a left-hand coiled spring.

This right-side braze-on uses a right-hand spring. Coils will contract when brake caliper is moved toward rim.

Additionally, some caliper arms have multiple spring-hole options for spring placement inside the arm. Mount springs into symmetrical holes for left and right calipers. The spring holes will allow you to change spring tension.

When installing calipers, grease springs and the braze-on before installing the caliper. The braze-on may have different spring hole options. It is typically best to choose the middle hole.

Mount and secure the brake calipers to the braze-ons. Use care not to over-tighten the mounting bolt. Generally, about 30 inch-pounds is adequate for cantilever caliper mounting bolts.

Pad Alignment

Brake pads attached to cantilever caliper arms and move to press on the rim braking surface. The pads do not move straight in toward the rim, but swing on an arc. This means the pads actually move downward as they move inward. Pad alignment to the rim is very critical to brake performance.

Brake caliper adjustments depend upon the wheel being adequately centered in the frame. A miss-aligned wheel will affect both pad centering and pad placement on the rim. Realign the wheel before beginning pad adjustments. The front wheel seen below is off to the viewer's right. Open the quick release skewer and adjust wheel centering before proceeding with caliper adjustments.

Brake pads are typically adjustable in several directions. The pad should be correctly adjusted for vertical height alignment, tangent alignment, vertical face alignment and pad toe. Not every brand or model of brake caliper has every adjustment, and sometimes you must simply compromise when setting pads.

Vertical Height Alignment:

This is the setting up and down on the rim-braking surface. View caliper face-on and move the arms, watching the pads move to the rim. Set the pad to the upper edge of the rim-braking surface, but never above the braking surface. As the pad wears thinner, it tends to move down on the rim braking surface.

Set height to top of braking surface.

Tangent Alignment:

This is the setting of the pad tilt. Viewed pad from the side, the front and back of the pad should be level to the rim. One side should not be higher or lower than the other side. Use care when tightening the pad fixing bolt and hold the brake pad to keep it from twisting.

Upper image is good alignment. Lower image is poor alignment. Front and back edges of pad should be even.

Vertical Face Alignment:

This is the setting of the pad vertical surface relative to the rim vertical surface. The vertical face of the pad should be set parallel to the face of the braking surface.

Pad face and rim surface should be parallel at time of contact.

Pad Toeing:

This is the setting of pad angle as it touches the rim. Toeing refers to setting the pad so the pad's front edge strikes first, which tends to reduce squeal during braking. Caliper arms tend to have play in the pivots and the arms flex when the brake is applied. This may cause squealing in the brake pads. It is simplest to first ride the bike and see if the brakes squeal.

Front of pad strikes rim first for "toe".

Most models of cantilever calipers use a "smooth stud brake pad." The brake pad is fitted with a non-threaded stud. The stud fits into a hole in a bolt head that secures to the caliper arm with a series of convex and concave washer and spacers. This system allows the pad face to adjusted to correct positions described above. Generally, it is easiest to adjust brake pads after the caliper arms are correctly positioned. The brake pads may prevent this. Loosen brake pad-fixing nuts on both sides of cantilever and lubricate threads, curved washers and washer-to-arm contact points.

Cantilever Adjustment Procedure

1. Turn brake lever barrel adjuster fully clockwise into lever body, then unthread six or eight complete turns.

2. Position caliper arm straddle wire. For straddle wire cable carriers using pinch bolt, this unit should be placed as low as practical. The bottom of the carrier should be approximately even with the lowest part of the rear seat stay bridge or front fork crown.
   

3. Fully secure pinch bolt of straddle wire carrier. The wire will become flattened by bolt. It can be awkward to hold carrier while tightening nut. Use an open end wrench on head of bolt. Hold so wrench opening is in line with cable.
   

4. For brakes using a "link unit", check the primary wire is correctly routed in link unit.
   

5. Pull primary wire through wire pinch bolt until lower section of caliper arms appear to be approximately parallel to one another. View area of caliper from frame mounting bolt to brake pad bolt. Consider this a line, and adjust brake calipers in and out until these lines are close to parallel.
   

   Note: Using a fourth hand tool (Park Tool BT-2) can make this procedure easier. Place tool on the cable about one inch (2.5cm)from caliper arm. Squeeze tool handle to grab cable and push against caliper arm. Loosen pinch bolt. To shorten wire, squeeze handle. To relax wire, relax handles.The caliper below was set so the arms are too far inward. The brake pads are not rubbing. When the straddle wire pulls, the arms will not be able to apply force to the pads and to the rims. In this case, loose the straddle wire, and reset pads more inward on both sides.

   

6. View centering of caliper arms to rim. Do not be concerned about pad centering at this time, only caliper arm centering. Most models of cantilever brakes use a centering set-screw on caliper arm to center. Turning set screw changes spring tension in that arm. For example, to move both arms right, turn right side set screw clockwise. To move both arms left, loosen screw counter-clockwise. Squeeze lever to work calipers and check centering again. Caliper arms should be centered to rim.

7. Attach rubber band around backside of pad. This is used in pad alignment only and is later removed. The rubber band creates a shim to give "toe "to brake pad. If it is difficult to mount the rubber band, remove one pad at a time from the caliper. Note pad orientation in mounting bolts, especially order of washers and spacers.
   

8. Re-install pad into pad fixing bolt and adjust only one pad at a time for correct alignment to rim. Push pad until it is touching rim, but do not push caliper toward rim. Align pad correctly in four positions as describe in Pad Adjustment above. View pad alignment from top, beneath, front and side.

9. Hold mounting bolt with hex wrench, and tighten mounting nut. Pad should be touching rim after adjustment. Tighten nut to about 70-inch pounds torque. This is about a 20 pound effort if you are holding thewrench three inches from the nut.
   
   • Vertical face-parallel to rim face.

   • Tangent-front and back edge of pad should be level to rim.

   • Height-close to top edge of rim ,but never above.

   • Toe-slight gap at back (rubber band will hold back edge out).

   • Remove rubber band from rear and view toe. There should be a slight gap at back of pad. Pad should be slightly rubbing rim at this time.

   • Loosen other pad, install toeing rubber band, and repeat adjusts as with first pad.

   • Both pads should be touching rim when pad adjustment is completed.

   • Squeeze lever multiple times to seat inner-wire and test inner-wire pinch bolt. Cable should not slip.

   • Set clearance at lever for rider preference. If brake feels tight, turn barrel adjuster clockwise to loosen inner-wire tension. If brake feels too loose, turn barrel adjuster counter-clockwise to tighten inner-wire tension. If barrel adjuster is all the way engaged at lever and brake lever is still too tight, loosen inner- wire pinch bolt and allow slack to feed through pinch plate. Tighten pinch bolt and test again. Use adjusting barrel at lever to set to preference.

   • View pad centering to rim. If not adequately centered, use centering set screw on caliper arm. Tightening screw increases spring tension, which pulls arms to side of set-screw. Loosening the set-screw allows the arms to move away from the set-srew side.
     
   • Inspect that pads are not rubbing tire. Re-adjust if necessary. Use care not to move brake pad stud in or out from caliper arm as this changes centering. Move pads only up/down, rotate, or twist as necessary.

Misc. Notes

It is not important that the brake pads strike the rim at the same time. It is more critical that pads have symmetrical clearance when full open.

Some brands and models of cantilever calipers have no centering setscrew or other system of centering. In this case move pads laterally as necessary in pad fixing bolts. Changes to spring tension at the braze-on is drastic, and typically will not solve alignment problems. Some brands use adjustable spring tension on each caliper at the mounting bolt. Spring tension can be changed on either arm.

Pad Wear

Pads will wear out with use and require replacement. Pads will also harden and become ineffective with age. Pads may also become embedded with aluminum or other contaminants. Inspect and remove as necessary. Pads that are aligned too low on a rim will tend to develop a lip on the low edge. This lip makes correct alignment impossible.

IN-LINE BRAKE LEVERS (CROSS LEVERS)

This article will discuss the installation of the in-line brake levers, also referred to as "cross levers." In-line brake levers are an additional set of brake levers that may be installed on drop-type handlebars.   In-line levers are installed above the primary brake lever, and allow the rider to actuate the calipers while riding on the top part of the handlebar (Figure 1). The in-line lever pushes on the housing, effectively making it longer, which causes the brake caliper to close on the rim.

Figure 1
In-line brake levers.

In-line brake levers are designed to clamp on specific bar diameters. Lever must be mounted to a compatible section of bar. Check the manufactures literature of the clamp to confirm compatibility. For most drop-style bars, the smaller outer section of the bar (where the primary lever is clamped) is approximately 23.4mm. However, the larger bulged or center section may be 25.4, 26.0, 26.4, or 31.8mm.

It is sometimes possible to re-use old housing and brake inner wire. However, it is recommended to install new brake housing and cables when installing in-line levers.

1. Remove handlebar tape at least down to the brake lever. Remove brake housing and cable (Figure 2).
   
   Figure 2. Untape bars and remove housing.
2. Mount in-line lever to the top section of the bar (Figure 3). Do not route housing under clamp of lever. Position lever for comfortable reach and angle (Figure 4).
   
   Figure 3. In-line brake levers.
   
   
   Figure 4. Adjust angle for comfort.
   
   
3. Tighten lever to bar (Figure 5). Do not route any housing under clamp of lever.
   
   Figure 5. Secure levers.
4. Cut housing lengths for in-line lever. There will be two sections of housing. One section goes from the primary lever to the in-line lever. The second piece of housing goes from the in-line lever to the brake caliper or frame housing stop as applicable (Figure 6). Use housing end caps where ever they will fit into levers or stops..
   
   Figure 6. Cut two sections of housing.
5. Feed brake wire through brake lever, through first section of housing, through brake lever, and through second section of housing. Attach brake wire to caliper and adjust brake as normal. Secure first section of housing to bar with tape (Figure 7).
   
   Figure 7. Housing is installed and ready to be wrapped.
6. Wrap handlebars. However, do not attempt to bring bar tape to lever as this may stress housing (Figure 8).
   
   Figure 8. Allow housing to reach stop in brake lever.

CASSETTE AND FREEWHEEL REMOVAL

This article will address the removal and installation of rear cogs on derailleur type bicycle, and of single speed freewheeling BMX/Freestyle bikes.

Typical Tools and Supplies Needed:

• Cassette cog remover FR series
• Sprocket Tool (chain whip) SR-1, SR-2, or HCW-16
• Freewheel tool wrench, FRW-1, (substitute large adjustable wrench or vise)
• Grease, such as PPL-1 or anti-seize type lubricant

See also related articles:

Hub overhaul (adustable type)

Freehub removal and service

The rear cogs are attached to the hub in one of two ways. Newer bikes tend to use type hub called a "cassette hub." The cassette hub uses a "freehub" sytem, which is a type of clutch mounted to the body of the hub. This cylindrical mechanism ratchets counter-clockwise for coasting, and locks clockwise for driving the bike when pedaled. The freehub body has a series of splines on the outer shell. "Cassette" sprockets slide over these splines. A lockring threads into the freehub and holds the sprockets, or cogs, in place. When the cogs are removed, the ratcheting freehub remains on the hub body. Most modern bicycles use the freehub system. See a typical cassette hub below.

Older bikes may have a large external thread machined into the hub. The cogs and ratcheting body assembly, called a "freewheel," threads onto the hub. The ratcheting mechanism comes off with the cogs when the freewheel unthreads for removed.

To remove rear cogs, begin by determining the style of hub, the style or brand of cogs, and the removal tool required. The removal tool must fit the part correctly, or both may become damaged. After removing the wheel, look at the flat surfaces adjacent to the right rear axle for brand names.

You will need to determine the style of hub you have and the style or brand of cog system. The table below shows several different options.

Shimano® and Sachs® screw-on freewheels-FR-1 (not the cassette-type freehub)	Older Suntour® two notched- FR-2
Suntour® four notched- FR-3	Atom® and Reginia®-FR-4
Shimano® cassettes, Sun Race®, Hugi®, Many brands- FR-5, or FR-5G with guide pin	BMX and Freestyle one-speed 4-notch freewheels-FR-6
Falcon® brand freewheels-FR-7	Campagnolo cassettes- BBT-5 (not Campagnolo freewheels)

There may be older model freewheels where a tool is no tool available. It may still be possible re-use the wheel but at the loss of the freewheel. See destructive removal of freewheels

Cassette Cog Lockring Removal and Installation

Shimano®, Campagnolo®, Sun Tour®, Sun Race®, Chris King®, DT-Hugi®, and other brands.

If your cogs look like this, you probably have a lockring type cassette.

With the modern cassette cog systems, all cogs are fitted with splines. Cogs slide onto the freehub body and are held in place by a lockring. The lockring sits outward from the smallest cog. Look for the word, "LOCK", and an arrow on the lockring indicating direction to turn for locking. Turn the lockring counter-clockwise, the opposite way of the arrow, to loosen it. There may be a loud noise when the lockring breaks loose. There is often knurling under the lockring to help keep it in place, and this knurling makes noise when the ring is loosened or tightened.
TOOLS: Park Tool FR-5, (For Campagnolo use BBT-5), Park Tool SR-1 sprocket chain whip (2 if possible), or large adjustable wrench or vise.

Mount bike in repair stand and remove rear wheel from bike.

a. Remove quick release skewer.

b. Inspect cassette and select correct type of remover.

c. Engage remover into splines/notches.

d. Install quick release skewer and install skewer nut on outside of remover.

e. Snug skewer nut against remover. Skewer acts as a holding device for freewheel removal tool.

f. Hold cogs in clockwise direction with sprocket chain whip tool. Turn remover counter-clockwise, using a large adjustable wrench, the hex end of another Park Tool sprocket chain whip tool SR-1, or the Park Tool freewheel wrench FRW-1. It will require force to remove the lockring. Expect to hear a loud clicking sound as the locking teeth of the lockring separate.

g. If using a vise, grab removal tool tightly in vise with wheel held flat. Use sprocket chain whip tool to turn sprockets counter-clockwise. Do not hold wheel while turning sprockets, allow wheel to rotate, and pull only on sprocket chain whip tool.

Using FR-5G with Guide Pin

Remove the skewer and install the FR-5G. Make sure the teeth are fully engaged in the lockring. Hold cogs as described above and turn FR-5G counter-clockwise.

Installing Cassette Cogs

Cassette freehub bodies and cassettes are often designed so the cogs will fit in only one orientation. This permits manufacturer to align "shifting ramps" to specification.

a. Inspect splines of freehub body. Look for a wide space between splines. Inspect the internal splines of cogs. Look for a wide spline to mate with wide space in freehub body. Align splines and engage all cogs.

b. Install spacers in same orientation as when removed.

c. Grease threads of lockring and thread lockring into freehub.

d. Install cassette lockring tool and install quick release skewer. Thread skewer nut on outside of lockring tool.

e. Snug skewer nut against remover. Skewer acts as a holding device for freewheel tool.

f. Turn remover clockwise until lockring is tight, at least 360 inch-pounds (approximately 40 Nm). For installing lockring, use of the sprocket chain whip tool is not required.

FR-5G speeds installation as well. Simply insert the FR-5G into the lockring splines and tighten fully.

Threaded Freewheel Removal and Installation

This type of freewheel requires the FR-1

These types of cog systems will have either recessed notches or splines that sit inside and lower than the smallest cog. Older Suntour freewheels had two recessed notches. Some Suntour freewheels come with four recessed notches. Shimano freewheels and Sachs freewheels have a series of small square shaped splines. Atom and Regina freewheel use a series of star shaped splines. Park Tool makes freewheel removes for all these types of freewheels. NOTE: Falcon freewheels have a larger spline than Shimano. Use only the FR-7. DO NOT use the FR-1 on the Falcon freewheels.

a. Mount bike in repair stand and remove rear wheel from bike.

b. Remove quick release skewer.

c. Inspect freewheel center and select correct type of remover.

d. Engage remover into splines/notches.

e. Re-install quick release skewer with skewer nut on outside of remover. If solid axle-type, use axle nut to hold frewheel tool.

f. Snug skewer nut against remover. Skewer acts as a holding device for remover.

g. Turn remover counter-clockwise using a large adjustable wrench. Park Tool removers will also fit the hex end of the Park Tool sprocket chain whip tool SR-1, or the Park Tool freewheel wrench FRW-1. It will typically require some force to turn the freewheel. Another option is to mount remover flats in hard jaws of vise, and turn rim counter-clockwise.

h. Turn remover only 1 full revolution counter-clockwise. Loosen and remove skewer before continuing to remove freewheel.

i. Continue to turn remover counter-clockwise until freewheel is unthreaded from hub. Lift freewheel from hub.

Installing Freewheel

a. Lubricate heavily with grease or anti-seize inside mounting threads of freewheel.

b. Lay wheel on bench, and hold flat. Hold freewheel so cogs are parallel to wheel rim and lower freewheel onto threads.

c. Sight right side of hub and freewheel. Axle should appear centered in hole of freewheel. If axle appears off center, freewheel may be cross-threaded on hub threads. Remove and re-align.

d. Begin threading cogs clockwise by hand until freewheel feels fully threaded. If a great deal of resistance is encountered, remove and attempt better thread alignment.

e. Use sprocket chain whip tool to rotate cogs clockwise. This will fully seat freewheel against hub.

f. If a new freewheel was installed or in new wheel installed, check all adjustments of the rear derailleur. See Rear Derailleur Adjustments.

There are some brands and models of thread-on freewheels that have use a lockring to hold the cogs to the freewheel body. This lockring can sometimes be removed, however, there is typically no need to do so. Individual cogs of these freewheels are not typically available. The lockring is used to assemble the freewheel unit, and it is not intended for service. When the cogs wear out, the entire freewheel as a unit must be replaced. In the freewheels below, notice the cog lockrings. The left freewheel uses the FR-2, a double prong freewheel tool. The right freewheel uses the FR-1, a splined tool.

Older Cassette Hubs (non-lockring ring type freehubs)

a.Older freehubs may lack notches or splines adjacent to axle. These older freehub cogs did not use a freewheel or cassette lockring removal tool. There will be a dust cap for the hub on the right side, but no recessed notches or lockring splines at all. The first cog acts as a lockring for the other cogs.

b.Use two sprocket chain whip tool (Park Tool SR-1 or SR-2)

c.Place first sprocket on second or third cog, holding it clockwise.

d.Place second sprocket tool on first cog to rotate it counter-clockwise.

e.Arrange sprocket tools so they form a "X". This gives you better mechanical advantage. See image above.

f.Rotate first cog counter-clockwise while holding second sprocket chain whip tool. This loosens first cog. Remove cog and pull off other cogs.

Installing Older Non-Lockring Freehub Cogs

a. Grease threads of smallest cog.

b. Install cogs and spacers on freehub.

c. Thread on smallest cog and secure clockwise with sprocket chain whip tool.

FREEWHEEL- DESTRUCTIVE REMOVAL

Typical Tools and Supplies Needed

• Pin Spanner SPA-2or SPA-6
• Punch and hammer (as option to pin spanner)
• Bench vise

This article will discuss removing older models of freewheels that have no removal tool option. It is possible to remove the freewheel, but the process below will destroy the freewheel. A new freewheel will then be required.

Begin by inspecting freewheel carefully. It is best to use the correct tool when available. See Cassette and Cog Removal for various Park Tool options.

Remove the wheel from the bike, and remove the quick release skewer or axle nuts (if non-quick release type). Inspect freewheel for cone. The cone will typically have pin holes. The cone of the freewheel is a left-hand thread. Turn it clockwise to remove. The cone is typically very tight. Hold spanner snug to freewheel while turning.

Alternatively, use a small tipped punch and hammer to drive the cone clockwise.

Inside will be ball bearings, pawls and springs. Lift the outer body of the freewheel off.

The inner body is now exposed. The inner body is threaded clockwise onto the hub shell. Grab the body firmly in a vise and turn wheel counter-clockwise. NOTE: Use eye protection as the inner body is hard and brittle steel. Dispose of the freewheel and install a new one.

FREEHUB SERVICE

Typical Tools and Supplies Needed:

• Cone wrenches, see DCW and SCW series wrenches.
• Combination wrenches, sizes vary.
• Hex wrenches: 10mm for Shimano®, some brands use an 11mm or 12mm.
• Pencil Magnet and seal pick
• Compressed air and blowgun
• Grease, Park Tool Polylube® 1000
• Solvent, such as Bio ChainBrite®
• Axle vise, such as AV-1, or AV-4
• Rags

Freehub Service

This article will discuss the service of freehub service of the following brands:

Shimano®,    DT-Hugi®,    American Classic®,    Campagnolo®,    Bontrager®,    Cane Creek® .

Consult the manufacturer for further information. The freehub is the ratcheting mechanism attached to the rear hub of most modern derailleur bike hubs. The freehub uses a splined cylinder to hold the cassette cogs. Inside the freehub mechanism will be bearings and a clutch system, usually ratcheting teeth and pawls. The cassette cogs have no moving parts. All moving parts are in the freehub body.

Most rear hubs allow the freehub body to be removed. The body can then be flushed with solvent for cleaning, dried, lubricated with oil, and then re-installed. Much of the process is similar to a Hub Overhaul.. To service the freehub, begin by removing rear cogs

The common Shimano® freehub uses internal loose ball bearing, pawls and springs. Be aware that it is not recommend to completely dismantling the freehub itself. There are no parts available, such as the pawls or springs. The small ball bearings are available as replacement parts. However, if the bearings are worn out and require replacing, it is very likely the entire freehub is needing replacement. The blow-up image seen below is a ball bearing type freehub.

The freehub pawls and bearings operate only while the bike is coasting. There is very little load or stress on the freehub during this time. When the bike is pedaled, the pawls lock onto the ratcheting teeth, and the freehub bearings take very little stress. Because of this, bicycle grease is typically not required inside a freehub. Most manufacturers recommend liquid lubricant for the inside of the freehub. With enough use, the freehub will simply wear out. The pawls may begin to slip and the bearings may become rough. If cleaning and lubricating the freehub does not resolve issue of slipping, sticking or noise, replace the freehub unit with a new one.

Freehub Service- Shimano® and loose ball bearing types

The procedure below is based on the Shimano® freehub removal process. Several other brands follow the same steps.

1. Remove axle as during hub overhaul. See Hub Overhaul if you are unfamiliar with this process.

2. Use a hex wrench to loosen and remove the freehub holding-bolt. Most brands are accessed through the right side, but a few are accessed through the left side. The bolt is typically very secure and may require much effort to loosen.
   
   
   
3. Note any spacer behind freehub.
   

4. Gently remove any seal behind freehub body.
   

5. Flush freehub in solvent, spinning body to remove dirt. NOTE: Do not attempt to pry out right side dust cap from Shimano® freehubs. Damage may result. Clean under dust cap using a brush and rags. Clean area above cap as well.
   
   

6. Blow dry with compressed air. Use normal precautions when using compressed air. If no compressed air is available, allow freehub to sit until completely dry.
7. Use a liquid lubricant in the back side and front. Spin freehub to work lube inside.
8. Grease freehub mounting-bolt.
9. Install freehub and any spacer onto hub body. Thread in freehub mounting-bolt and secure fully. Tighten to about 360 inch-pounds. If you are holding a wrench 6 inches from the bolt, apply 60 pounds of effort.
10. Assemble and adjust hub as with Hub Overhaul.

American Classic® Freehub

The American Classic® freehub contains cartridge bearings. These may be removed and replaced.

Freehub Removal

1. Hold drive side axle securely in an axle vise.
2. Hold non-drive side sleeve nut with cone wrench and loosen locknut counter-clockwise. Pressed-on axle cap will prevent locknut from being completely removed. Make sure locknut is spinning freely and is not engage on thread.
   

3. Loosen sleeve nut. Sleeve nut will press against locknut and act as a press to remove axle cap. Remove cap, locknut and sleeve nut.

4. Remove axle by pulling on drive side.
   

5. Pull freehub to remove from hub shell. Pawls are inside hub shell. Clean and flush all ratcheting parts. Use care not to get solvent in cartridge bearings.
   

6. Grease the pawls and teeth of the freehub. Install freehub into shell.

7. Install axle and assemble non-drive side parts. Axle should turn smoothly with no side-to-side motion after adjustment.
8. Install non-drive side axle cap.

DT-Hugi® Freehubs

The DT-Hugi® freehub uses cartridge bearings inside the body.

1. Pull on freehub body to remove from shell. This will remove drive side axle cap and freehub body.
2. The clutch is composed of two gears. The angled teeth face one another. The gear inside the hub shell rides on a spring.
   
   <

3. Clean parts. Use care not to get solvent in cartridge bearings.
4. Grease gears and spring.
5. Install one gear inside freehub with smooth side facing freehub, and toothed side facing hub shell.
6. Install spring inside hub shell, with small end facing toward freehub.
7. Install second gear into hub shell, with smooth side facing hub shell and teeth side facing freehub body.
8. Slide freehub onto axle and press to seat freehub over seal.
9. Install drive side axle cap.
   

Campagnolo® Freehub

Chorus and Record freehubs are held on by the axle. The freehub body holds cartridge bearings. The axle is independent of the freehub.

1. Remove set screw from side of drive side locknut.

2. Hold non-drive side cone with cone wrench. Loosen and remove drive side locknut.

3. Pull freehub to remove. Use care not to loose small parts. Note orientation of pawls as you remove freehub.
   

4. Clean parts as needed.

5. Grease springs and pawls, and install into freehub.

6. Engage freehub inside hub shell. It can be difficult to engage pawls into hub shell. If necessary use the Campangolo® UT-HU080 tool. You can also tie a string around the pawls to help engage it into the shell, then pull the string loose.

Bontrager® Freehub

The Bontrager hub uses a cartridge bearing system.

1. Remove quick release skewer and cassette cogs.
2. The left side of the axle is fitted with a hex hole. Use a 6mm hex wrench to hold the axle. Loosen the axle nut on the right side using a 17mm wrench.
   

   Freehub slides off axle after axle nut is removed.

   

3. Axle can be removed by loosening the left side sleeve nut. Hold axle with a 6mm hex wrench and loosen sleeve nut coutner clockwise. Axle will slide out once sleeve nut is removed.
   
   
   

Freehub ratchet may be cleaned and re-greased. The cartridge bearings may be tapped out and pressed by in with new bearings. If bearings are not to be replaced, do not removed bearings.

Cane Creek Freehub (Aros, Volos, Zonos, Duros)

Cane Creek uses a cartridge bearing system in the hub and freehub.

1. Remove quick release skewer and cassette cogs.
2. Loosen left side pre-load adjusting ring setscrew.
   
   
   
   
3. Use fingers to loosen adjusting counter-clockwise, away from hub.
4. Insert two 5mm hex wrenches into each side of the axle. Turn right side axle end cap clockwise to loosen. NOTE: end cap is a left hand thread. Remove end cap.
   
   
   
   
5. Pull axle to the left and remove axle from hub.
   
   
   
   
6. Grab freehub and pull it away from hub body.

The installation of the freehub is basically the reverse of assembly.

1. Engage freehub into hub body. It may be necessary to squeeze pawls to fit freehub fully into body
   
   
   
   
2. Install axle into hub body from left side.
3. Grease threads of
   end cap. Thread end cap onto axle. NOTE: End cap is a left hand thread. Secure end cap to 300 inch-pounds.
4. Push axle side to side and note any movement. Turn pre-load adjusting ring clockwise until no side to side movement detected. Snug setscrew. Adjustment may also be done with wheel in the frame and skewer loading the bearings.

CHAIN LENGTH SIZING

Typical Tools and Supplies

• Chain Tools-CT-2, CT-3, CT-5 or CT-6
• Repair Stand to hold bike (optional but nice)
• Special Replacement pin for Shimano® or special link for Campagnolo® chains as appropriate
• Tape measure (optional, for "Equation Method" only)
• Chain Lubricant CL-1 Synthetic Blend Chain Lube
• Rags

This article will discuss sizing derailleur chain to length. See also related articles:

• Chain- removal and installation
• Fixing tight chain links
• Cleaning the chain

Chains for derailleur bicycle should be an adequate length. A chain that is too long or too short can cause shifting and riding problems. However, the rear derailleur cage should be long enough to take up slack as the chain is moved between the different gear combinations. This is referred to as "total capacity", and is discussed below.

This article will describe three methods to achieve adequate chain length. All three methods tend to yield adequate chain lengths. It is not necessary to use all three methods, as one method may appeal to you and your situation. The first system described is the EXISTING CHAIN method. It assumes the bike already has a chain in place. The second system is LARGEST COG-TO-LARGEST CHAINRING method, and does not require the pre-existing chain. The last system is the EQUATION METHOD, and uses simply math to determine chain length.

NOTE ON REAR SUSPENSION: If the bike has a rear suspension linkage, it is usually necessary to account for the movement of the rear hub from the bottom bracket. If the rear hub moves away from the bottom bracket, set chain length is the longest position. Consult the bike manufacturer for correct chain length if in doubt.

DERAILLEUR CAPACITY: The derailleur capacity refers to the derailleurs ability to take up chain slack as the derailleur shifts between different gear combinations. Some bicycles may have sprocket combinations that do not allow the derailleur to take up the chain slack. In this case, the gearing on the bike exceeds the capacity of the derailleur. If the derailleur capacity does not match the gear sizes on the bike, the chain may appear to fail either the “too long” test or the “too short” test. A chain length cannot be found that will pass both tests. In this case it is better to size a chain for too long rather than too short. Both the EXISTING CHAIN and EQUATION methods below will safely size a chain when a bike is violating the derailleur capacity. It may be necessary to avoid gear combinations that cause problems in pedaling or shifting on these bikes.

Chain Sizing-Existing Chain Method

Before removing the old chain, check the bike for acceptable length. Cut the new chain relative to the old chain length.

Shift bike to smallest chainring in front and smallest cog in back. Inspect the section of chain between lower derailleur pulley wheel and bottom of smallest chainring. There should not be an obvious sag in the chain. Check also that the lower section of chain does not rub chain at upper pulley. It is normal for there be low chain tension in this position, but the chain should not sag. Sagging in this position indicates a chain that is too long.

Too long a chain length sags in smallest cog front and rear. Note chain-to-chain contact at upper pulley.

Adequate chain length will not sag.

If the chain is too long, find the chain rivet contacting bottom of chainring, and mark the chainring at this point. Count two chain rivets toward derailleur, lift this rivet and move to position of mark. Chain is now effectively shorter. Check for sag again. Repeat counting two rivets and moving to chainring mark. Number of rivets to shorten must be an even number (2, 4, 6, etc.) Repeat until chain has no visible sag.

To determine if the chain is too short, shift chain to largest chainring and second largest rear cog. Chain will appear tighter in this position. Inspect chain for "S" bend as it passes through pulley wheels. Shift slowly and carefully to largest rear cog. If chain appears to jam, it is too short. If chain does shift, but there appears to be no double bend of the chain at the pulley wheels, it is too short. You will need to add two rivet lengths to new chain compared to the old chain. NOTE: Do not attempt to lengthen an old chain by adding new links.

Adequate chain length seen above in largest sprockets front and back. Note the chain bends at both pulleys.

Chain length in the two images above short it is too short. Note the lack of an obvious bend at pulleys.

If the current chain length passes one of the tests above, but fails the other, it is likely the dereailleur capacity does not match the gearing on the bike. Set the chain length so it passes the large ring to largest rear spocket test. It will then be the responsibility of the user to avoid shifting to gear combinations that cause chain slack.

If a new chain is being installed and the old chain is the correct length, the new one may be shortened to the old length before being installed. First, remove the old chain and lay it on a flat surface with the rollers aligned vertically. Pull the chain straight. Lay the new chain next to the old chain in the same fashion. Make sure the ends of the two chains match, with either a rivet or no rivet at each end. The new chain will appear shorter, so push the links of the old chain back to match up with the new chain. Locate the matching end rivet on the new chain with the rivet on the old chain. Add or subtract chain links as necessary from inspection results stated above and cut the chain at this point.

Chain Sizing - Largest Cog and Largest Chainring Method

An alternative method for determining chain length for new chains is to use the largest size sprockets on the bike. It is easiest to size the chain without threading it through the derailler.

1. Remove the old chain.
2. Shift the front derailleur over the largest chainring, and the rear derailleur on the smallest cog.
3. Thread the new chain through the front derailleur. It is not necessary to thread the chain through the rear derailleur at this point. Simply wrap the chain around the largest front chainring and around the largest rear cog.
4. Pull the chain tight, and note the closest rivet where the two could be joined. Keep in mind a chain can only be joined by mating inner and outer plates.
5. From the closet rivet, lengthen the chain by counting over an additional two rivets (two links), which is a distance of one-inch. Cut the chain at this point.
6. Remove the chain from the bike and thread it through both derailleurs and join the ends.

MASTERLINK NOTE: If the bike chain uses a "master link", it is necessary to account for the link. Install one-half of the master link on one side of the chain. Size the chain by cutting the other end of the chain.

Chain Sizing by Equation

Bicycle chains consist of inner and outer plates. It is only possible to join inner plates to outer plates. Because of this, chains can only be connected at even inch increments. For example, some derailleur bike chain could only be 51, 52, 53 inches, etc. Chains cannot be cut to 52-1/4”, 53-1/8”, or even 52-1/2”. It is possible to determine chain length from industrial drive train equations, and then cut the chain before installing it on the bike.

Begin by counting the number of teeth on the largest front sprocket and largest rear. These numbers are often printed right on the sprockets and cogs. Next, measure the distance between the middle of the crankarm bolt to the rear axle. This is also the chain stay length. Measure to the closest 1/8”, and convert this to decimal form. A simple chart below will assist this conversion.

Fractional conversion to decimal for 1/8” measurements:
1/8” = 0.125”
1/4" = 0.25”
3/8” = 0.375”
1/2” = 0.5”
5/8” = 0.625”
3/4" = 0.75”
7/8” = 0.875”

For most bicylces, a relatively simple chain length equations may be used. For bicycles with extreme differences in chainring sizes and short chainstays, the more rigorous and complete equation may be used. This is discussed later in this article.

SIMPLE EQUATION: L = 2 (C) + F/4 + R/4 + 1

L = Chain length in inches. Round the final result to closest whole inch figure.
C = Chain stay length in inches, measure to closest 1/8”. Use chart below to find decimal measurement.
F= Number of teeth on largest front chainring.
R= Number of teeth on largest rear cog.

Example: A bike has a 42-32-22 front chainring set up. Use only the 42 for the equation. The rear cog set has 32 tooth largest cog. The bike measures 16-3/8” from the center of the rear axle to the center of the crank bolt. The decimal equivalent for 16-3/8” is 16.375 inches.

L = 2 (16.375) + 42/4 + 32/4 + 1

In the example above, this becomes 32.75 + 10.5 + 8 + 1 = 52.25 inches. Chains cannot be joined at 52.25 inches, so this length is rounded to 52 inches.

For this system, round up from 0.5. For example, a chain length figured to be 55.5 would be rounded to 56 inches.

To measure the new chain, lay it on a flat surface with the rollers and plates aligned vertically. Pull on each end to straighten out the chain. Measure from either end. Remember, you can only shorten the chain at whole inch increments. If the chain uses a master link, install it on one of the chain for purposes of measuring, and measure including the master link.

Rigorous Equation

Examples of bikes using the rigorous equation would be a track bike with a large front ring, perhaps a 55 tooth, and a small rear cog, such as a 11 tooth. Additionally, to require the rigorous equaution, the bike would need a very short chainstay, such as 15 inches or under in length. As the front and rear sprockets differ more in size, the chain must diverge more off a line represented by the chainstay. This is the hypotenuse of a triangle, which can add to the chain length. Again, it is only a concern in very extreme cases.

For an example of the rigorous equation, assume a one speed bike has a 15 inch chain stay, a 58 tooth front ring and an 11 tooth rear sprocket. For one-speed bikes, eliminate the "1" at the beginning of the equation. This is the extra inch added by derailleur manufacturers when sizing chain. The short equation yields an answer of 47.25 inches, which should be rounded to 47 inches. The rigorous equation yields an answer of 48.17 inches, which is rounded to 48 inches. The short equation would be an inch too short. This again is an extreme situation. Even in this one-speed example, if the chainring is reduced to a 55t, the two equations come up with the same answer.

CHAIN INSTALLATION (CT-2, CT-3, CT-5, CT-6, CT-7)

Typical Tools and Supplies

• Chain Tools-CT-2, CT-3, CT-5 or CT-6
• Repair Stand to hold bike (optional but nice)
• Special Replacement pin for Shimano® or special link for Campagnolo® chains as appropriate
• CL-1Synthetic Blend Chain Lube
• Rags

This article will discuss the removal and installation of chain on derailleur bicycles. See also related articles:

• Chain Sizing- derailleur chain
• Fixing tight chain links
• Cleaning the chain

Chains are made up of a repeating series of inner plates, a roller, a chain rivet (also call a "pin"), and outer plates. The chain rivet presses into both outer plates,but the rivet slides freely through the inner plates and the roller. Chains have a small amount of play at each link, even when brand new. As a chain is ridden, it wears the rivets, and the play at each link increases. This is sometimes called "stretch", although the plates do not literally become longer. A worn chain will not engage the cogs correctly, and will eventually slip over the cog teeth when pressure is applied. To check chain wear, use the CC-2 Chain Checker, or the CC-3. New chains can be fitted to the bicycle, although new chains are longer than required and must be shorted to the correct length.

To install or remove a chain, a chain tool is required. Chain tools are made up of adriving pin and a cradle to hold the chain-roller. Some models have two cradles. The primary cradlesupports the chain plate for pressing the chain rivet in and out. The tight link cradle is only for fixing a tightlink. The service procedure will vary between brands of chains. Always check theinstallation instructions on a new chain.

The Park Tool CT-3 and CT-5 are designed for use with 3/32" derailleur type chain. The CT-2 will service both 3/32" and the wider 1/8" chain. The CT-7 will work on 3/16 inch chains and 1/8 inch chains common on freestyle bikes. The CT-7 will not work on derailleur chains.

When installing a chain, keep in mind that most chain failure is due to one of the pins being improperly installed. Modern chains are very narrow, and even a small amount of misalignment in rivet as it sits in the side plates could cause the chain to break under load. Check even new bikes by viewing each and every pin for protrusion at the side plates.

Also inspect any pre-mounted chain for bent side plates or missing rollers. Inspect side plates for deformity or other anomalies.

Procedure for Shimano® Chain

Some chains, including Shimano®, use chain rivets which are peened. This creates a "mushroom" effect at the ends of the rivets, which adds to the strength of the chain side plates. When a rivet is pressed even partically out, this peening is sheered off on the side pressed by the chain tool. If this rivet were reused, it would create a weak link at that rivet. In the image below, a Shimano® rivet is shown in an optical comparator, which magnifies the rivet. The original peening is seen at the bottom of the rivet. The top of rivet has the peening sheered off. This top section was pushed through the outer chain plate.

Shimano® chains use a special replacement rivet when the chain is installed new or when one is removed and re-installed. This replacement rivet has special flaring that is guided in by a long tapered pilot. The pilot is then broken off before riding. Only Shimano® brand chains should use the Shimano® replacement rivet. The 7 and 8 speed chains use a black rivet. The narrower 9 speed chain uses a silver-colored rivet.

Shimano® Chain Service Procedure

a. Select a chain rivet that has peening marks. These may be either double peening marks (two parallel marks at rivet ends), or a peening completely around the rivet. Avoid selecting the special replacement rivet, and avoid any rivet that looks different from the others.

Some Shimano® chains use a rivet around the entire head.

b. Place the roller of the chain fully in the primary cradle of the chain tool.

c. Turn the chain tool pin until it contacts chain rivet and stop. Note position on handle.

d. For most non Park Tool brand chain tools, turn handle 5complete turns. Use care not to drive outchain rivet. For Park Tool CT-3, drive T-handle until it is stopped by C-clip. For Park Tool CT-5, drive T-handle until bodystops screw.

e. Back out chain tool pin and lift chain out of cradle.

f. Grab chain on either side of protruding rivet. Flex chain toward the protruding chain rivet then pull on chain to separate.

g. Pull on non-rivent end to remove chain from bicycle.

To reinstall the special replacement rivet:

a. Reinstall chain on bike with protruding chain rivet facing away from you.

b. Open outer plates slightly and insert inner plates. Align protruding rivet with hole in inner plate.

c. Install special Shimano® replacement rivet into chain rivet hole, with tapered end first. Replacementrivet will protrude outward toward you.

d. Back chain tool pin into tool body to make room for replacement chain rivet.

e. Place roller into primary cradle of chain tool.

f. Drive replacement rivet into chain. Replacement rivet will drive out original rivet. Continue to drive until chain tool pin is almostadjacent to outer side plate.

g. Remove the chain from tool and inspect rivet. Non-tapered end of replacement rivet should protrude same as any neighboring rivet. Press further if necessary. Image below shows a protuding chain pin. Repair as necessary.

h. Break off pilot of replacement rivet. With Park Tool, use groove of body of CT-3 or CT-5and twist pilot sideways. Pliers can also beused to break rivet. Inspect rivet again and press further if necessary.

i. The replacement chain rivet should not be used again to separate the chain. Re-using same rivet hole wears plate holes and may weaken chain. Use other original rivets for future chain cutting.

j. Inspect for tight links and repair as necessary. Shift to a gear that will relax derailleur cage. Pedal backwards and note any hoping or jumping of chain as it passes through pulleys. See also Tight Link Repair.

Re-useable Rivet-type Chains

There are several brands of chain that are serviced by pressing out a rivet partially, then re-pressing the same rivet to re-install. Check with the manufacturer's literature when in doubt.

a. Inspect chain for "master link", if any. Disengage master link according to manufacturer's instructions.

a. If no master link is present, place a roller of the chain fullyin the primary cradle of the chain tool.

b. Drive chain-tool pin until it contacts chain rivet.

c. For most non Park Tool brand chain tools, turn handle 5 complete turns. Use care not to drive out chain rivet. For Park Tool CT-3, driveT-handle until it is stopped by C-clip. For Park Tool CT-5, drive T-handle until body stops screw.

d. Back out chain-tool pin and lift chain out of cradle.

e. Grab chain on either side of protruding rivet. Flex chain toward the protruding chain rivet then pull on chain to separate.

f. Remove from bicycle by pulling on rivet end of chain.

To reinstall the chain rivet:

a. Re-install chain on bike with protruding rivet facing toward mechanic.

b. Open empty outer plates slightly and insert inner plates. Push inner plates until hole aligns with chain rivet.

c. Back chain-tool-pin into tool body to make room for chain rivet.

d. Place roller into primary cradle with chain rivet facing chain tool pin.

e. Drive chain rivet back into chain, taking care to center rivet exactly between both outer plates. If more chain rivet appears on one side of outer plate than other, push rivet until it is evenlyspaced.

f. Inspect for tight links and repair as necessary. See Tight Link Repair.

Master-Links in Derailleur Chains

Some chain manufacturers offer a "master-link" to join the chain. Be sure to read the manufacturer’s directions. Typically, the bicycle chain ends must have inner plates on each end. In other words, neither chain end has an outer plate with a rivet. The link comes in two pieces.

Install one piece through inside face of chain, and install second piece through outside of the other chain end. Engage the two pieces so link rivet mates to link plate hole. Pull chain to lock the link. The best method to do this is to move master link to top section between rear cogs and front chainrings and press hard on pedals. This insures the link is fully locked. Inspect link before riding the chain.

Note: Some masterlinks are reusable, while others are disposable and should be replaced after each removal. Check manufacturer's specifications.

Campagnolo® 10-speed Chains

These chains currently use a special system called the HD-Link. It consists of a short section of links and two special piloted rivets. When determining chain length, you must deduct an additional amount of chain equal to this section.

Both ends of the special link section are out plates, and these must attach to the inner plate section of the chain. Install the pilot into the chain rivet and place this into the chain. Engage pilot and rivet so that the rivet faces the inside of the bike, toward the spokes. The pilot is then pushing outward, away from the spokes.

     

It is especially important with the Park Tool chain tools to press downward on the chain at rivet to keep in fully engaged. In the image below, the thumb presses down on the chain.

After the rivet is fully pressed, remove the pilot simply by pulling outward.

Installing Chain Through Derailleurs

The chain is routed through the rear and front derailleurs before being joined. It is best to first determine chain length before instaling chain.

a. Shift front and rear derailleur under smallest rear cogs.

b. Pull back on rear derailleur and feed short section of chain over the tension pulley and straight to the guide pulley.

NOTE: Double chain chain routing at between pulleys. Chain should not drag on any part of the derailleur cage. Image on left shows correct routing. Image on right shows incorrect routing.

c. Pull chain behind rear cogs and then foward toward front rings.

d. Hold a short section of chain and feed chain through front derailleur cage. Turn cranks slowly as you feed chain onto smallest ring.

e. Joint chain at lower section between front and rear cogs. Use correct procedure according to brand of chain. See process above.

f. After installing the chain, check for any tight links. Before riding the bike, check the derailleur adjustment.

TIGHT LINK REPAIR (CT-3, CT-5, CT-6, CT-7)

Typical Tools and Supplies

• Chain Tool with loosening shelf option: CT-3, CT-5, CT-6
• Repair Stand to hold bike (optional but nice)
• Chain Lubricant CL-1 Synthetic Blend Chain Lube
• Rags

This article will discuss loosening a tight link on a derailleur chain. See also related articles:

• Chain Length Sizing
• Chain Installation
• Chain Cleaning

Tight links are typically the result of the two outer chain plates pushing tightly against the inner two chain plates. If pressure on the inner plates can be removed, the tight link can be fixed.

Some chain tools such as the Park Tool CT-3, CT-5, and CT-6 have a tight link repair system built into the tool. The following procedure demonstrates how to use the tight link repair system.

NOTE: Some nine-speed and ten-speed chains have narrow rollers and may not fit the tight link cradle. It will be necessary to loosen the tight link by hand, as described in below.

1. Locate the tight link. Put chain in smallest rear sprocket in back and on the middle ring of a triple crankset, or the smallest ring of a double crankset. This relieves tension on chain and makes problem links show up easier.

2. Back pedal slowly and watch chain as it passes through the two jockey wheels of the rear derailleur. Look for a popping or jumping of chain, or movement in derailleur arm. Keep backpedaling slowly. Tight link should show up as it passes by the tight bend of the lower jockey wheel.
   

3. Isolate tight link and move it to lower section of chain between chainring and rear cogs.
4. Engage tight rivet in tight link cradle.
   

5. Run chain tool pin up to tight pin and note position of handle.
6. Turn handle only one-eighth to one-quarter turn clockwise. This presses on rivet to spread chain.
7. Remove chain tool and feel tight link.
8. Repeat as necessary, pushing rivet from other side of chain.
9. Inspect chain rivet. Rivet must be centered in chain plates.

Tight Link Repair without Chain Tool

It is also possible to repair tight links without the tight link cradle system. This method requires physically stressing and flexing the chain laterally. Use care not to bend and deform the plates by using too much force. To avoid damaging your chain, practice on a section of scrap chain. Your hands are likely to get dirty from grabbing the chain. If this is a problem use a rag over the chain.

1. Locate the tight link as described above.
2. Grab either side of chain with your hands, and place both thumbs at the tight rivet.
3. Pull outward with your hands, while pressing inward with your thumbs to flex the tight link.
4. Reverse pressure to flex chain the opposite direction. Pressing inward with your hands and pressing outward with the index fingers centered on tight rivet.
5. Pivot link back and forth to see if it is free and repeat if necessary.

CHAIN CLEANING (CM-5)

Useful Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• CM-5 Cyclone Chain Scrubber
• Degreasing solvent CB-2 Citrus ChainBrite
• Rubber gloves such as MG-1Nirile Mechanic's Gloves
• CL-1Synthetic Blend Chain Lube
• Rags
• Soap and water

This article will discuss the use the CM-5 Cyclone® Chain Scrubber. The concepts will also apply to other chain cleaners.

Dirt and grit on the chain will eventually cause wear on the chain rivets, inner plates, and rear cogs. Chains and chain lubricants tend to attract dirt, which may conatain small pieces of hard material such as quartz. The image below is chain dirt magnified 200 times, showing the mix of typical grit. Park Tool ChainBrite® solvents break down the grit by making it smaller, as seen in the right image, again magnified 200 times. It is then necessary to flush this grit way, which is what the CM-5 does.

0

To begin any cleaning operation, start by finding an area to work. Chain cleaning by its nature is messy. Hold the bike in a repair stand. Rotate the bike so the lower section of the chain is level. Shift the bike to the smallest cog in the rear and the middle chain ring in the front. Test for smooth back pedaling.

Place CM-5 under lower section of chain. Push chain down into rollers. Check that the chain is fully engaged on the sprocket in the large roller.

Lower top cover into place and close each end clip. Practice spinning pedals with the CM-5 dry. Hold the CM-5 with the left hand and back pedal with the right hand. If the CM-5 is twisted side to side, it may derail the chain.

Fill CM-5 with solvent such as Park Tool CB-2 Citrus ChainBrite to the "Fill Line."

Hold CM-5 and backpedal. Count to at least 30 revolutions of the pedal. Remove the CM-5 and dispose of solvent. Wash the CM-5 out and clamp again onto the chain. Fill with water and soap to the fill line. Back pedal to flush chain.

Remove CM-5 and wipe chain dry with cotton rag.

It is often useful to also clean the sprockets. Use the Park Tool CGS-1 GearGlean® Brush to clean and scrape cogs. To get cogs even more clean, use a rag between cogs as a "floss".

After the chain is dry, lubricate chain with your preferred lubricant. Place a drop of lubricant at each roller and rivet.

CHAIN TENSION ON ONE SPEED BIKES

Typical Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• Axle nut wrenches
• TW-2 Torque Wrench, if available

This article will address the adjusting chain tension on bicycle with a single sprocket in the rear and a single sprocket in front. See related article, tandem chain tension. It is assumed there is no derailleur or other chain tensioning devise. For derailleur chain sizing see chain sizing. Also see coaster hub overhaul.

The rear wheel on a two sprocket bikes can be moved forward and back to allow for adjustment to chain tension. Generally, the chain should be set tight enough so that it does not come off during use. Too loose a chain setting will fall off either the front or rear sprocket. Too tight a chain setting will bind the hub and bottom bracket bearings. To set chain tension, the frame must have rear frame dropouts with slots that are somewhat horizontal. If the slot is vertical, the wheel cannot be moved relative to the front sprocket to change chain tension.

The rear wheel should be aligned straight in the frame. If the wheel is off to either left or right side, the rear sprocket will not be running straight to the front sprocket. To change the tension, loosen the axle nuts and move the wheel forward or back. If the bike uses a coaster brake, loosen the brake arm clamp bolt. IMPORTANT: The brake arm clamp bolt must be fully secured before the bike is used.

As a rule of thumb there should be about one-half inch (12mm) movement of the chain up and down at a between the front and rear sprockets. Push the chain downward and then pull it upward in the middle. Note the travel.

After setting chain tension, pedal the bike in the repair stand and check for any tight and loose positions as the crank arms turn. It is common for sprockets to be out of round. This will result in the chain being tighter in some points of its rotation. After setting chain tension, pedal the bike in a repair stand and check the tenion all the way through the crankarm rotation. If necessary, readjust so there is only one-quater inch (6mm) movement at the tightest point.

To test the tension adjustment, pedal the bike and push sideways on the chain at a point in between the front and rear sprockets. The chain should not derailleur from the front rings. Repeat the test by pushing sideways on the chain on the lower section. The chain will make a rattling sound, but it should not derail. If the chain comes off, increase tension by moving the wheel further back.

Secure rear axle nuts to 300 to 400 inch-pounds. This is approximately 60 pounds of effort if you are holding a wrench six-inches from the axle.

If the bike uses a coaster brake, make sure the coaster brake arm is fixed to the bike and the coaster arm is secure.

CRANK REMOVAL & INSTALLATION- ISIS DRIVE OR OCTALINK

Typical Tool and Supplies Required:

• Wrench for crank bolt, typically 8mm. Some models may require 10mm. See Hex Wrenches.
• Crank Remover CCP-4, or CWP-6
• Grease, such as PolyLube® 1000

This article will discuss the removal and installation of crankarms on the round, splined type spindles. These are the ISIS Drive® or Shimano® Octalink types. For service of square-tapered type crankarms, see Square Tapered Spindle Type crankarms. NOTE: There is a crank-spindle interface called "power spline" that uses a spline spindle. The crank bolt is an 8mm thread. Because the hole in the spindle is small, use the CCP-2 or CWP-6 for this crank, the same tools for a square spindle.

The oversized pipe billet splined spindles are round at the ends rather than square shaped. A series of internal splines in the crank are mated to external splines on the spindle. The cranks are held tightly to the spindle by tension from the crank bolt. Certain road and MTB models of Shimano® cranks uses an 8-spline design called Octalink®.

Another standard is the ISIS DRIVE® (International Spline Interface Standard). The ISIS DRIVE® system uses ten splines of a different shape from Shimano®. The ISIS DRIVE® and Octalink® systems do not interchange for either cranks or spindles.

For all types of cranks, the first step of removal is to turn the crank bolt counter-clockwise. Two things might occur. First, the bolt may simply come out. In this case, inspect inside the crank for the end of the spindle. Remove any washer seen inside. If the crank has a square hole, or if the bolt diameter is 8mm (about 5/16"), see Square Spindle-Type Crankarms.

Splined or "pipe billet" cranks will have a round hole in the crank where it meets the spindle.

The second possibility is the crankarm bolt presses back against a crankarm cap, or retaining ring, and the entire arm is pulled off. This is the case if the arm uses a one-key-release system. One-key-release systems use a metal cap threaded into the crankarm. This metal cap takes the place of the dust cap and surrounds the crankarm bolt head. To remove the crankarm, leave the ring in place. Turn the crankarm bolt counter-clockwise and the bolt backs against the ring pulling the arm from the spindle. Both oversized pipe billet spindle and square type spindle system may come with the one-key-release system, and both are removed the same way. It can occur that the one-key-release cap or retaining ring comes loose. To secure rings using pin-holes, use the Park Tool SPA-2 pin spanner. Some cranks use a larger 10mm hex hole in the cap. Use the PH-10 for this system. No crank extractor is required for the one-key-release system, as seen below.

For oversized pipe billet crankarms not using the one-key-release system, such as some ISIS Drive® and some Shimano® systems, use Park Tool CWP-6, or CCP-4. These removers use a large rotating tip that fits over the end of the spindle.

Crankarm Removal-Non-One-Key-Release Type

1. Remove crankarm bolt and any washer inside the arm.
2. Unthread nut from handle stud of CCP-4 or CWP-6 until the tip is flush with the nut. This allows tool to have full thread contact inside the crank.
3. Thread nut into crankarm and tighten with wrench until snug. If nut is not completely threaded into crankarm, the threads of the arm or nut may be damaged.
4. Thread handle stud into nut. When resistance is felt, continue threading handle stud into nut until crankarm is removed.
5. Repeat process on other arm.

Crankarm Installation

Use care when installing the crankarm to the spindle so splines match correctly. Crankarms using the one-key-release system make it difficult to see how the arm is fitting to the spindle. A forced mismatch on the splines can damage the arm. Splined type crankarms without the one-key system allow easy viewing of the spline fit. The spline pattern on the spindle consists of a series raised splines separated by flutes or recesses, at the minor diameter.

Keep the raised spline aligned at the top 12:00 position.

a. Grease threads inside bottom bracket spindle. Grease splines on spindle.
b. Rotate pipe billet spindle so one spline aligns to top dead center, at the 12:00 position.
c. Position right crankarm on to spindle so arm points straight down at the 6:00 position. Place crankarm on spindle and carefully thread bolt into spindle. View opposite side of spindle and check that a narrow spline is aligned to top dead center. Threading should continue without resistance until crankarm visually covers spindle splines.
d. Tighten bolt fully. If possible use a torque wrench and secure to 305-391 inch-pounds.
e. Align left arm so it points directly opposite from right arm. Thread bolt into spindle and tighten fully.

CRANK INSTALLATION AND REMOVAL- SQUARE SPINDLE TYPE

This article will discuss the removal and installation of cranks from square spindle bottom brackets. Crank pullers are used for two basic crank types: the square spindle type arms, and the splined type spindle arms. The left image below is a crank with the bolt removed. The square spindle can be seen inside the square fitting in the arm. The right image shows a bottom bracket bearing unit with square spindle.

For the splined Shimano® Octalink and ISIS Drive® type crank arms see Spindle Cranks..

Typical Tools and Supplies Required:

• Crankbolt wrench: typically 8mm hex wrench for newer bikes, such as HR-8
• 14mm or 15mm socket and driver (older bikes), or Park Tool CCW-5 for 14mm size bolt head or 8mm hex cap screw
• Crank puller- Park Tool CCP-2 or CWP-6
• Adjustable wrench
• Rags
• Grease
• Torque wrench, if available, such as TW-2, and correct socket bits for crank bolt/nut

Cranks connect the pedals to the bottom bracket spindle. The arms are pressed tightly to the bottom bracket spindle. Cranks must be removed from the spindle to service the bottom bracket bearings. On some models of cranks, the cranks must be removed to replace the chainrings. "One-key release" systems do not require a crank puller. The one-key system cap is seen below.

Crank Removal (Square Spindle Type)

a. Shift chain to largest chainring to protect hands against chainring teeth.

b. Look for bolt or nut at end of crank in line with bottom bracket spindle. If no bolt is visible, remove dust caps. Some caps pry out and some thread out. NOTE: If the bike has a one-key release system, leave this cap in place. A retaining ring surrounds the bolt. Simply turn the center bolt counter-clockwise to remove arm of one-key release system.

c. Turn bolt or nut head counter-clockwise and remove bolt or nut. Inspect inside arms for washers. Remove washers if present.

d. Before installing crank puller into crank, turn puller nut away from internal driver as much as possible. If puller nut happens to unthread from internal driver, thread it back on only 3-4 turns.

e. Thread large external thread of puller (nut) into arm, taking care not to cross thread. Tighten puller nut into crank using wrench. If puller nut will not thread into arm, or if threads in arm are stripped, see Removal of Cranks with Damaged Threads.

f. Thread internal driver into puller nut. Using handle or adjustable wrench, tighten driver until crank is loose on spindle. Pull arm from spindle and unthread both parts of tool from arm. Use care not to skin knuckles when removing tool.

g. Repeat process on other crank.

Crank Installation(Square Spindle Type)

Cranks are pressed tight onto the tapered square spindle. The square spidle is made with a slight upward sloping taper. The crank square fitting also has a slight taper. The crank bolt or nut acts as the pressing tool and forces the arm up the slope of the spindle. The bolt or nut must be tight enough to keep from loosening, but not so tight that the spindle splites and damages crank. If possible, use a torque wrench. See Torque Recommendations.

Aluminum cranks typically do not require lubrication of this press fit. Aluminum by its nature is self-lubricating as it is covered with a thin layer of oxidation. Adequate torque is typically enough to keep arms from creaking.

a. Wipe both sides of spindle and inside crank mounting holes with a rag.

b. Grease under head and threads of both bolts or nuts.

c. Install right crank onto right side of spindle.

d. Thread crank bolt/nut to spindle.

e. Tighten crank bolt/nut to manufacturer's recommended torque.

f. Grease threads of dust cap (if any) and install snug.

g. Install left crank onto left side of spindle with arm pointing opposite direction of right side arm.

h. Install crank bolt/nut and tighten.

i. Grease threads of dust cap (if any) and install snug.

EXTERNAL (HOW TO) BEARING CRANK SYSTEMS (HOLLOWTECH II, MEGAEXO, GIGA X PIPE, X-TYPE)

Typical Tools and Supplies:

• Park Tool BBT-9
• Hex Wrenches
• Thread preparation, options include Polylube® 1000 grease, anti-seize, and thread lockers

This article will discuss service of the "external bearing cranksets." Examples are Shimano® Hollowtech II, Race Face® X-type Crankset and FSA® MegaeXo, and Truvativ® Giga X Pipe. These systems integrate the bottom bracket bearings, crank and spindle. The spindle is a permanent part of one arm. The opposite arm slides onto the spindle splines and is then secured. While conventional bottom bracket system have the bearing inside the bottom bracket shell, these types of cranksets have external bearings that sit outboard of the shell face. Example of these systems are Shimano® Hollowtech II, Race Face® X-type Crankset and FSA® MegaeXo, and Truvativ® Giga X Pipe.

The external crankset bearing systems integrate the bearings, cranks and spindle. The bearings sit outside the face of the bottom bracket shell face. The spindle is a permanent part of one arm. The arm slides onto splines and is then secured. These systems use a cartridge bearing.

The bearings cups of these systems thread into the bottom bracket, and press against the shell face. The bearings then sit outside of the shell. It is important that the left and right shell surfaces are adequately machined square to the threads and one another. Miss aligned shell faces can cause the bearing cups to twist as the seat into the bike.

MTB-Type Cranksets

The table below outlines the spacer arrangement for the Shimano® XTR FC-M960, XT FC-M760, Saint FC-M800, Race Face® X-type, and FSA® MegaeXo bottom bracket bearings as installed into 68mm and 73mm shell widths. The E-type brackets and International Standard Chain Guide bracket options are also listed. The bearing cups are of a similar design, and cups are designed to be spaced 75.5mm apart. Three spacers of 2.5mm are supplied to achieve this width. E-type front derailleur brackets, or a chain guide mount, are counted toward the width total.

Bottom Bracket Shell Width	Front Derailleur or Chainguide	Non-Drive (left side of bike)	Drive Side (right side of bike)
68mm	Clamp on	2.5mm spacer	2 x 2.5mm spacers
68mm	E-type derailleur bracket	2.5mm spacer	2.5mm spacer plus E-type bracket
68mm	Chainguide system	2.5mm spacer	2.5mm spacer plus chainguide
73mm	Clamp-on	No spacer	2.5mm spacer
73mm	E-type front derailleur	No spacer	E-type bracket
73mm	Chainguide	No Spacer	International Standard Chain Guide bracket only

           

NOTE: The Shimano® FC-M761 is sometime used with a "crankcase" shifting system. More spacers are included for this model:68mm shell band type: Left cup-2.5mm spacer; Right cup-1 each of 2.5mm, 0.7mm, and 0.8mm
68mm shell chaincase stay type: Left cup-2.5mm; Right cup- chaincase stay, 0.7mm spacer, 2.5mm spacer
68mm E-type bracket: Left cup- 2.5mm spacer; Right cup- E-type bracket, 2.5mm spacer, .8mm spacer
73mm band type: Left cup- no spacer; Right cup- no spacer
73mm chaincase stay type: Left cup- no spacer; Right cup- chaincase, 0.7mm spacer
73mm E-bracket type: Left cup- no spacer; Right cup- E-bracket only

Road-Type Cranksets

The Shimano® Dura-Ace FC-7800 crankset, Truvativ® and FSA® road cranksets are designed for a 68mm bottom bracket shell. No spacers are required or used for the road systems.

Frame Preparation

The bearing cups thread into the bottom bracket shell and press against the shell face. It is important that the left and right shell face surfaces be machined square to the threads and one another. If a bearing cup is secured to a shell with miss aligned faces, the two bearings will not align properly with each other. Unlike conventional cartridge bottom brackets, these bearings use the shell face as a reference for alignment. Shell faces that are not parallel may cause a twist or load to the bearings. See Bottom Bracket Machining for details on facing and machining.

Prepare threads of shell with either grease, anti-seize, or a mild thread locker. For more on thread preparation, see Basic Thread Concepts. Install correct amount of spacers on cup marked with "R" (left-threaded cup) and install dust sleeve on cup. Thread cup counter-clockwise into right side (drive side) of bike. Use care not to cross thread cup. Tighten fully, approximately 305 to 435 inch pounds. When using the BBT-9, and grabbing the tool about 6-inches (15 cm) from the cup, apply about 60 pounds of effort (27 kilograms) of effort to tighten the cups.

Install correct spacers as needed on cup marked “L” (right-threaded cup). Thread cup clockwise into left side (non-drive) of bike and tighten fully as before.

Shimano® Hollowtech II Procedures

The Shimano® XTR FC-M960 Hollowtech II is seen below. The Dura-Ace system is similar in design, but uses different cups and no spacers. The right side arm contains the spindle. The left arm is secured with two pinch bolt. A crank cap is used on the left arm for bearing adjustment. The cap does not hold the crank, it is only for adjustment.

After bearing cups are installed, grease spindle surface and place right crank with spindle through the right side cup (drive side). Push from right side until spindle comes out left cup. Fit is snug, and in some cases gentle use of a mallet may help.

If spindle appears to catch and will not come out non-drive side cup, may be an indication that shell faces need machining. Grease splines of spindle and install left arm. Notice splines are keyed, and left arm will only install 180-degrees opposite of right arm. Grease threads of arm cap and thread cap into spindle. This cap acts only to push arm fully over to cup bearing. This cap does not tighten the arm onto the spindle. IMPORTANT NOTE: Secure cap gently. Use the eight sided stud a the end of the BBT-9 and tighten only 4 to 6 inch-pounds. Over tightening will side-load the bearing and cause premature wear. Spin arm to test.

Use a hex wrench and secure bolts at compression slot. Secure to 88 to 132 inch-pounds. Secure bolts evenly, working first one and then the other.

Disassembly

IMPORTANT NOTE: First, loosen the two left crank pinch bolts at end of arm. Next, loosen and remove arm cap and slide arm off. It it sometimes necessary to gently tap arm with mallet. Pull crankset to right to remove right arm and spindle. Use BBT-9 to remove both cups. Non-drive side removes counter-clockwise. Drive side removes clockwise.

FSA® MegaeXo Crankset

The FSA® system shares some of the same service features as the crankset previously described. The right side arm contains the spindle. The left arm is pressed gently against the bearing cups by the arm cap.

Begin by installing bottom bracket bearing cups as described above. The arrangement of spacers is the same as shown in the table. Grease spindle surface and press right crank through right side. The fit is snug, and mild use of a mallet may at times be useful. Place left arm on to spindle splines. Grease thread of crank cap and thread into spindle. Use a 8mm hex wrench and GENTLY snug the cap. The left cap simply bring the arm over to the bearing. It is used as a bearing adjustment, and it does not secure the right arm.

Secure the left crank with the pinch bolts in the arm. Alternately tighten each bolt until both are fully tight. Check arms for play.

Race Face® X-Type Service

The X-type crankset left arm has a permanently pressed spindle. The spindle has ten splines, but these are not symmetrically aligned. The ISIS Drive® system arms will not fit this spindle. The drive side arm is secured to the spindle with a crank bolt.

Begin installation by installing bearing cups as describe above for Shimano®, using the BBT-9. Arrange cup spacers as described in the table above.

The left crank uses an elastomer washer that will preload the bearings. The chainline is adjusted with 1mm spacers. No spacers are used on the right arm to achieve the 48mm chainline. One spacer on the right arm will give a 49mm chainline, and two spaces a 50mm.

Grease spindle surface and install spindle through left side on bike after installing appropriate chainline washers. The fit of the spindle may be snug and some mild force may be necessary. Use a rubber mallet with care. Guide the spindle through the right cup, and install any needed chainline washers.

Grease internal threads of spindle, and grease spindle splines. Align right arm 180-degrees from left arm and begin to turn bolt clockwise using a 8mm hex wrench. Secure bolt to a torque of 360 inch-pounds to 600 inch-pounds. Bolt will come to a “hard stop” as the arm fully presses to spindle.

The X-type right side crank has a one-key release system. The retaining cap use a left-hand thread, and is secured to the arm with a 10mm hex wrench. It is not necessary to remove the one-key system. To remove the arm, use a 8mm hex wrench on the crank bolt and turn counter-clockwise. One-key system will remove arm from the spindle. After removing the right arm, pull the left arm to remove. It may be necessary to use a mallet and tap spindle to free the arm.

The image below shows the one-key system. It is not necessary to remove the system for either removal or installation.

Truvativ® Giga X Pipe

The Truvtiv® Giga X Pipe is a road-type crankset system. The bottom bracket cups are designed for the 68mm bottom bracket shell width. Cups are marked with thread direction arrows and torque specifications.

The spindle is a permanent press fit into the driveside arm. Each cup is tightened into the bottom bracket shell as with the systems above. No spacers are need or required.

Both cups are tighten to 300-360 inch-pounds. Grease the splines and surface of the spindle and insert through the right side cup. Install left arm and tighten. There is no "bearing adjustment". The drive side cup has a rubber lip that compresses as the arms are pressed. As the splined left arm is tightened, it compressed the lip.

Tighten left arm to 360 to 420 inch-pounds. The left arm has a one-key release system. No puller is required to remove, simply use 8mm hex wrench and turn crankbolt counter-clockwise.

REMOVAL OF CRANKS WITH DAMAGED THREADS (SQUARE TYPE ONLY)

If the removal threads for the crankarm puller in the crankarm are damaged, there is a possible repair. Begin by inspecting the threads. If only the outer threads are bad, you may still be able to remove it using a normal tool. Make sure the thread of the remover are clean. Start the tool straight to the threads and carefully thread it in place. Tighten the tool into the crank threads with a wrench before attempting to pull the arm. Even if there are only a few threads left, it is worth trying to remove the arm with a crank remover.

Another repair option involves a tool from the Bicycle Research Company, the TC-8. This is bascially a fluted bolt that cleans the threads. It comes with a pivoting stud to align the tool centered to the threads. This tool in not a tap, it only aligns damaged and cross-threaded threads. It will not cut new threads. Typically, it will not damage threads, so there is nothing to lose in trying it. The TC-8 will work only with square drive cranks with an 8mm threaded bolt.

If the threads are completely stripped, the is basically ruined. The arms can be typically removed, but it will be unusable. The simplest removal method is to understand how arms keep from falling off. Pressure from the crank bolt keeps it on, so you need to remove that pressure. Loosen the bolt or nut three or four turns. Ride the bike hard, uphill. The crankarm hole is a tapered fit onto a tapered spindle. The flexing will cause the arm to loosen, but it will also cause the crankarm hole to become enlarged, ruining the arm. Use care when riding, you don't want the arm to fall completely off when pedaling.

It is also possible to use a hacksaw to cut into the arm at the spindle joint. A cold chisel can then be used to split the arm. Again, the arm is basically ruined when the threads are completely stripped, so destructive removal should be considered as an option.

FRONT DERAILLEUR ADJUSTMENTS

Useful Tools and Supplies

• Repair Stand, holds bike secure for easy work.
• Hex wrenches as needed.
• Screwdriver (#2 Phillips or straight blade)
• Light liquid lubricant
• Derailleur cable inner wire and housing as needed
• Caliper or metric ruler
• Cable end caps and housing end caps as needed
• Rags

This article will discuss the basic adjustment of the front derailleur. See also related articles:

• Rear derailleur- limit screws and index settings
• Wire cable-sizing and cutting inner wire cable and housing (gear and brake)
• Brake and Shift levers
• Rear derailleur- overhaul
• Rear derailleur- bent hanger

This article assumes the derailleur is compatible with the shifting system and is not extremely worn out. Cable and housing length is not covered in the article, see How do I cut cable and housing and how long should housing be?

Service Procedures

The front derailleur simply shoves the chain off one front chain ring and onto another ring. The cage surrounding the chain is pulled in one direction by the inner wire. A spring in the derailleur returns the cage to the other direction when the inner wire is relaxed. A properly adjusted front derailleur should shift the chain between the front chainrings but will not throw the chain off the rings. The basic adjustments for the front derailleur are the height, rotation, limit screws and inner wire tension (index setting).

It is generally a good idea to lubricate the pivot point of the front derailleur with a light lubricant. The cable inner wires should also be lubricated. If you have loosen the inner wire pinch bolt, lubricate those threads as well. When tightening this pinch bolt, secure to approximately 30-40 inch-pounds. This is about 10 pounds of effort hold a wrench 3 inches from the bolt.

Front Derailleur Height

Before checking limit screw adjustments, check the derailleur positioning. If the derailleur cage is too far above the large chainring, it is more likely to shift poorly. If the derailleur is too low, it may scrape against the chainrings or jam the chain when shifting.

Some front derailleur models do not have height or rotation adjustments. These models mount on a plate and both height and rotation settings are pre-set. Additionally, some bikes have a bracket commonly referred to as a "braze-on" for front derailleur mounting. This bracket will allow limited height and rotational settings.

1. Inspect height alignment of front derailleur. The outer cage plate must be positioned over the largest chainring when viewing height. Simply grab the exposed front derailleur inner wire until outer cage plate is directly over outer chainring teeth. Use care to not shift the derailleur cage past this point. Note height and direction of change needed. It is then necessary to relax the cable to loosen the mounting bolt and raise or lower the height as needed.
2. The gap between the teeth of the outer chainring and lower edge of the outer cage plate should be 1-2mm, about the thickness of a penny. Using a penny or a dime as a feeler gauge, fit it between the chainring teeth and the cage plate. It should just fit between the teeth and plate.
   
   
3. To lower cage, release inner wire tension completely by shifting to innermost chainring. Note angle of outer cage plate relative to chainring.
4. Front derailleur clamps typically leave a mark on the frame, which is useful as a reference when changing height. Loosen derailleur clamp bolt, change derailleur height, and return cage to same rotation relative to chainring. Tighten clamp bolt. Move outer cage plate over outer chainring, and check height again. Repeat this process until cage plate height is 1-2mm above outer chainring.

Front Derailleur Rotational Angle

The front derailleur cage should be approximately parallel to the chain. If the derailleur cage is rotated too far from this position, it will shift poorly. If the derailleur mount is a clamp type, its rotation can be changed. Generally, the outer cage of the front derailleur should be aligned to the chain. The middle image below shows adequate alignment.

1. Shift chain to outermost chainring and outermost rear sprocket.
2. Sight chain from directly above chainrings. Consider the chain as representing a straight line. Compare this line to outer derailleur cage plate. Outer cage plate and chain should be parallel. Keeping the cage and chain parallel will minimize the risk of the chain jumping off the outermost ring. If cage is not parallel, there will be a relatively large gap at either the back or the front end of the cage, and the chain may over shift.
3. If derailleur cage needs to be rotated, note direction of desired rotation.
4. Release inner wire tension by shifting to the innermost chainring.
5. Many clamps leave a slight marking on the frame. Use this scarring as a reference when changing height. It is also possible to use a pencil to make two reference marks on the frame, one for height and a second, vertical mark, to reference rotation. Use the marks to avoid inadvertently changing height.
6. Loosen clamp bolt and slightly rotate in correct direction. Use care not to change height. Tighten derailleur clamp bolt.
7. Shift to outer chainring and observe rotation alignment. Repeat adjustment if necessary.

NOTE: Some front derailleur models do not have height or rotation adjustments. These models mount on a plate and both height and rotation settings are pre-set. Additionally, some bikes have a bracket commonly referred to as a "braze-on" for front derailleur mounting. This bracket will allow limited height and rotational settings.

Front Derailleur Limit Screw Settings

Limit screws stop the inward and outward travel of the front derailleur cage. Limit screws are marked "L" and "H". The L-screw will stop the motion of the derailleur toward the smallest chainring. The H-screw will stop the motion of the derailleur toward the largest chainring.

If the limit screws lack any marking, you will need to determine which are the "H" and "L" by testing. Begin with the chain on the smallest cog. Relax the cable tension completely using the cable barrel adjuster. Place a hand on the derailleur body to feel for any lateral motion, and select one screw to turn one full turn clockwise and then counter-clockwise. If you felt motion in the derailleur, this is the "L" screw. If there was no motion, do the same test with the other limit screw. You should consider marking the "L" screw permanently. The other screw by default is the "H" screw.

Although the limit screws will stop the derailleur, it is the inner wire and derailleur spring that make the derailleur move. If the inner wire has too much tension, the derailleur will not rest on the L-screw stop. If the inner wire tension were to change, the derailleur inner limit would also change, possibly causing the chain to fall off the rings.

Front Derailleur - Adjusting L-screw

The L-screw controls the inward most travel of the front derailleur. Set adequately, it allows the chain to shift to the smallest ring, but not beyond so it falls off.

1. Shift chain to innermost rear sprocket and innermost front chainring. Inspect derailleur for marking indicating "L" screw.
2. Check inner wire tension. It should be fairly loose at this time. If inner wire is taut, turn barrel adjuster clockwise into housing. The barrel adjuster is typically located where the cable housing enters the shift lever. If barrel adjuster is already fully turned into housing, loosen inner wire pinch bolt, slacken inner wire and retighten bolt.
3. Sight gap between inner chain plate and inner cage plate. Only a small gap should be visible, about 1/16" or 1mm, about the thickness of a dime.

   

4. Pedal bike slowly and continue to sight gap. Set clearance at tightest point in chainring rotation. Adjust L-screw so there is a small gap between inner cage and inner chain plate. Pedal bike and check that chain is not rubbing cage as chainrings turn.

   1. If there is no gap and chain is rubbing cage, loosen L-limit screw 1/8 turn (counter-clockwise). Inspect for gap again and repeat until slight gap appears.2. If the gap appears larger than 1mm at its widest point, tighten the L-screw, in small increments, until the gap closes.

5. Test the shift by shifting chain to next chainring then shift back to the innermost ring. Do not use the shift lever. Pull on the inner wire to shift the derailleur. Using the lever may confuse limit screw issues with cable tension issues. If chain shifts quickly, limit screw setting is adequate.
6. If the shifting appears is slow (requires more than one pedal revolution to initiate shift), turn L-limit counter-clockwise 1/8 turn and repeat test. Repeat 1/8-turn increments until shifting is adequate. The gap will open wider than the 1mm target, but will still be as small as possible with adequate shifting.
7. If chain is shifting beyond the inner ring and falls off the chainring, gap may be too large or cage alignment may be off. Tighten L-screw 1/8 turn and check shift again. If chain ends up rubbing inner cage of derailleur, yet still drops off inner ring when shifting, other problems such as chain line or derailleur rotation exist.

Front Derailleur- Adjusting H-screw

The outward travel of the front derailleur is stopped by the H-screw. When viewing the H-limit adjustment, make sure there is enough tension on the inner wire by either keeping extra pressure on the lever, or by pulling the exposed inner wire taut by hand. Use a rag to protect your hand if pulling the inner wire. After the H-screw is adjusted the inner wire should be re-tensioned to assure proper shifting.

1. Shift to outermost sprocket in rear and outermost front chainring. Inspect derailleur for mark indicating H-screw.
2. Pull inner wire with hand to increase tension to insure derailleur is against H-screw.
3. Maintain full pressure on inner wire and check gap between chain and outer cage plate. Only a small gap should be visible, about 1/16" or 1mm. Pedal bike slowly and continue to sight gap. Set clearance at tightest point in chainring rotation.
   
   

   A. If chain is rubbing cage, loosen H-screw 1/8 turn and pull fully on inner wire. Check gap again.
   B. If chain is not rubbing, tighten H-screw repeatedly until chain is 1mm

4. Test shift to the large ring. Shift derailleur from next to largest to largest ring using hand pressure on inner wire rather than shift lever. If shifting is slow, loosen H-limit screw slightly and repeat test. If chain shifts off the outside of the large chainring, the outer-limit is set too loose. Tighten H-screw limit and test shift again.

Front Derailleur- Adjusting Indexing (Three Chainring Bikes)

Some front derailleur systems have an index setting. If the shift lever has three distinctive stops or clicks, it is indexing. If the front shift lever is friction, there is no index setting. If the front shift lever has multiple clicks, such as some twist grip style shifters, it is shifted similar to friction levers. Set indexing only after completing all adjustment above.

1. Shift chain to middle chainring in the front and innermost rear sprocket.
2. View gap between inner cage plate and chain. Gap should be as small as possible without rubbing chain.

   

3. To reduce gap, increase inner wire tension by turning barrel adjuster counter-clockwise. Adjusting barrel may be on frame or on shift lever. Check gap again.
4. If chain is rubbing cage, turn barrel adjuster clockwise, or inward toward shifter body.
5. If barrel adjuster is all the way in or out and no adjustment is possible, reset inner wire tension. Shift to innermost chainring and loosen inner wire pinch bolt. Pull wire gently with fourth-hand tool and tighten pinch bolt. Begin adjustment of inner wire tension as above.

   

6. Test shift of front derailleur to all three front chain rings. If the derailleur rubs in the largest front chainring, double check H-limit screw and inner wire tension, which may be too loose. If chain is slow to shift to smallest chainring, double check L-limit screw and inner wire tension, which may be too tight.

Front Derailleur- Adjusting Indexing (Two Chainring Bikes)

Some front derailleur systems have an index setting. If the shift lever has two distinctive stops or clicks, it is indexing. If the front shift lever is friction, there is no index setting.

1. Shift chain to outer chain ring in the front and outermost rear cog.
2. View gap between outer cage plate and chain.
3. If outer cage plate clears chain, index setting is adequate.
4. If plate is rubbing chain, increase inner wire tension by turning adjusting barrel counter-clockwise and check again.
5. If barrel adjuster is all the way in or out and no adjustment is possible, reset inner wire tension. Shift to innermost chainring and loosen inner wire pinch bolt. Pull the wire with fourth-hand tool and tighten pinch bolt. Begin adjustment of inner wire tension as above.
6. Test shift of front derailleur to both front chainrings.

Front Derailleur Performance

The front derailleur should shift the chain between chainrings without throwing the chain off the extreme outer and inner rings. It is possible that the front derailleur will rub the chain slightly even on properly adjusted bikes. This is likely on some bikes when riding in the largest sprocket in front and the smallest cog in back. As the bike is pedaled with force the frame flexes and moves the chainrings side to side, which cause an intermittent rubbing noise. Loosening the H-limit would move the front cage out more, and may stop the rubbing, but it may also cause the chain to shift over the largest ring and come off. If all aspects of front derailleur adjustments are correct on this bike, the rider is simply exceeding the engineering and design capabilities of the machine.

REAR DERAILLEUR ADJUSTMENTS

Rear Derailleur Adjustment

Typical Tools and Supplies Needed:

• Repair Stand, PRS and PCS stands.
• Screwdriver, Phillips #2 or straight blade
• Hex Wrenches, if changing inner-wire AWS series.
• Light lubricant
• Forth Hand Tool BT-2
• Cable cutter, if trimming cable CN-10
• Rags

The article will discuss the adjustment of the rear derailleur. See also related articles:

• Front derailleur- limits screws and index settings
• Wire cable-sizing and cutting inner wire cable and housing (gear and brake)
• Brake and Shift levers
• Rear derailleur- overhaul
• Rear derailleur- bent hanger

Derailleur bicycles have several sprockets on the rear hub. By using different combinations, the rider will find low gears for going up hill and high gears for going down hill. The gear system needs maintenance and adjustment to perform well. The cable system may also need replacement as it wears. The derailleur limit screws and index setting will need periodic checking. This article will first discuss limit screw setting, and then index adjustments.

Derailleur Limit Screws (H-Screw and L-Screw)

Rear derailleurs "derail" or shove the chain off of one sprocket and move it to another. The upper derailleur pulley (called the "guide pulley") pushes the chain to the next sprocket. A proper gear adjustment aligns the guide pulley under the sprocket.

Changes to the inner wire tension causes movement in the derailleur. The derailleur body is fitted with a spring that is pulled tight, or relaxed, by the inner wire. Pulling the inner wire moves the derailleur cage and guide pulley in one direction and tightens the spring. Relaxing inner wire tension allows the spring to move the body and pulley in the opposite direction.

It is normal for a chain to make some noise during a shift. The shift may appear subjectively "noisy," "loud," or "rough". Factors like the type of chain or sprocket, the wear on each, and the amount and type of lubrication will affect the noise a chain makes during shifting. The limit screws typically can do nothing to affect the noise during a shift between cogs. Noise from the chain as it rides on the sprocket is, however, a useful symptom. There is for any given bike a "base level" of noise from the chain as it passes over the sprocket teeth. When the derailleur jockey wheel is out of alignment, the chain may make excessive noise. To demonstrate the "base level" noise, shift the bike to the second sprocket by pulling the inner wire. Continue to pedal and move the inner wire slightly to hear changes in the level of noise. The quietest level of noise may be considered the base level for that bike.

Derailleur pulleys are limited in both inward and outward motions by using the derailleur limit screws. Properly set, the derailleur will shift to both the extreme outward sprocket (the smallest in size) and the extreme innermost sprocket (the largest in size). The limit screws do not control the derailleur on the sprockets between the two extremes. These are set using the barrel adjuster and tension on the inner wire. The limit screws are usually marked "H" and "L". The "H" controls the outer most limit of the derailleur, and the "L" controls the inner most limit.

Using the shift lever to adjust limit screws can cause confusion and problems because it tends to focus attention on the inner wire tension (indexing) rather than limit screw settings. Instead of using the shift lever, pull the inner wire with one hand to simulate shift lever action. This will help eliminate confusion between indexing problems and limit screw problems. With the bike in a stand, practice shifting with this method before adjusting the limit screws.

Turning the limit screws adjusts the limit of travel of the pulleys. Tightening restricts the travel, while loosening allows more travel. The purpose of the following procedure is to find the tightest H-limit screw setting that will allow a good shift to the outermost cog, and the tightest L-screw setting that will allow a good shift to the innermost cog. The location of limit screws on the derailleur body may vary between manufacturers. Always look for the "H" and "L" marked adjacent to the screws.

H-Limit Screw

Shift chain to outermost (largest) chainring. Shift chain to outermost rear sprocket (smallest sprocket).

Check tension on rear inner wire. If inner wire appears to have any tension, it may interfere with the H-screw setting. Turn adjusting-barrel clockwise to eliminate inner wire tension. Proper cable tension (indexing) will be adjusted later.

Pedal bike at a quick cadence, approximately 60 rpm or more.

Pull inner wire to shift derailleur one sprocket inward. Adjust pull on inner wire until chain rides quietly on second sprocket. Release inner wire quickly to shift back to outermost sprocket and note shift. When adjusting the H-screw, be concerned with two situations:

1. The outward shift from the second sprocket to the outermost sprocket.
2. How the chain rides on the outermost sprocket.
3. Do not be concerned with how the chain rides when it is held on the second sprocket.
4. If the shift outward seems acceptable, tighten H-screw 1/4 turn clockwise and repeat shift. Even if shift appears acceptable, continue tightening H-screw by 1/4 turn increments and checking shift until shifting is slow or hesitant. Another symptom of a too tight H-limit screw is when the chain is on the smallest cog but makes a rattle from rubbing the second sprocket inward. View this last symptom by looking under the rear sprockets where the chain meets the sprockets. The inner plate of the chain will rub against the next sprocket inward making the noise.



5. When symptoms of a too tight H-screw appear, loosen H-screw 1/4 turn and check shift again. Repeat process of shifting and correcting by 1/4 turn increments. When too tight symptoms disappear, H-screw is at tightest acceptable setting, and limit screw setting is done.

NOTE: "Rapid Rise" or "Low-Normal" derailleurs use a reverse spring application. When the inner wire tension is completely relaxed, the derailleur sits on the inner most sprocket, which is reversed from other common derailleurs. When adjusting the H-limit screw, it is necessary to pull the inner wire until the chain is in the second to outermost sprocket then pull hard to shift to the outermost sprocket. The same concept is used to adjust the Shimano® "Rapid-Rise" or "Low-Normal" derailleurs. You want the tightest limit screw setting that allows good shifting to the extreme outer and inner cogs.

L-Limit Screw

The L-limit stops the derailleur from moving inward (toward the spokes). The limit screw does not make the derailleur move, pulling the inner wire makes the derailleur move. The L-screw allows the pulley wheels to shift the chain to the innermost sprocket and yet not shift off the sprocket into the spokes.

1. Shift bike to middle chainring (or smaller ring of double chainring bikes) and to second-to-innermost rear sprocket.
2. Pedal bike at a quick cadence, approximately 60 rpm or more.
3. Pull inner wire by hand to shift derailleur sprocket inward. When adjusting the L-screw, be concerned with two situations:
   1. The inward shift from the second-to-innermost sprocket to the innermost sprocket.
   2. How the chain rides on the innermost sprocket.
   3. If shifting seems adequate, tighten L-screw 1/4 turn, and repeat shift. Continue to tighten L-screw until symptoms of too tight appear. These symptoms are that the chain will not complete shift even with pressure on inner wire, the chain hesitates before shifting inward even with constant pressure on inner wire, or the chain rattles excessively when riding on innermost sprocket

      

   4. When symptoms of a too tight L-screw appear, loosen L-screw 1/4 turn and check shift again. Repeat process of shifting and correcting by 1/4 turns. When too tight symptoms disappear, L-screw is at tightest acceptable setting, and limit screw setting is done.
   
   

   B-Screw Adjustment

   After setting the L-screw, check the "B-screw" for an adequate setting. The B-screw controls the derailleur body angle, hence the name, B-screw. Shift to the innermost rear cog, which is the largest cog. View the upper pulley relative to the largest cog. If the pulley is rubbing against this cog, tighten the B-screw to increase upper pivot spring tension, which pulls the pulley back and away from the cog. If there is a large gap between the upper pulley and cog, loosen the screw. To find a good setting, loosen the B-screw until the upper pulley begins to rub, then tighten the screw to get clearance.

   

   

   Check for rubbing of largest sprocket and upper pulley

   

   

   Change B-screw as necessary

   Campagnolo®
   Some Campagnolo® model derailleurs have a body tension adjustment at the pulley cage, not at the upper pivot. The screw is basically a "rack and pinonquot; system. The cage spring plate rotates to increase or decrease tension. The upper pivot and lower cage pivot springs oppose one another. In this system, the upper spring is fixed. Increasing cage tension (turning screw clockwise) will bring the upper pulley closer to the cog. Decreasing cage tension (turning screw counter-clockwise) will increase the distane between upper pulley and cog.

   

   SRAM® Derailleurs
   Sram® designates a 6mm between the largest rear cog and the upper pulley. Use a 6mm hex wrench to help estimate this gap.

   NOTE: Shimano "Rapid rise" or "Low-Normal" Shimano® "Rapid rise" derailleurs or "Low-Normal" reverse the spring direction from conventional derailleurs. The derailleur moves inward (toward the spokes) when the cable tension in relaxed, or or "normal" position. To adjust L-screw, pull on inner wire and shift outward one sprocket, then release inner wire to shift inward. Tighten L-screw until shifting is slow, then turn counter-clockwise 1/4 turn until good shifting is restored.

   The process above sets the limits to the tightest setting that still shifts well. This allows the derailleur to wear with use and time, and yet still allow a good setting. After limit screws are set, proceed to index adjustments.

   
   

   Checking the Rear Indexing Adjustment

   The rear indexing adjustment should only be done after the H-limit and L-limit screws are adjusted. The rear derailleur indexing is adjusted by changing the inner wire tension. For the common rear derailleurs, increasing inner wire tension tends to move the rear derailleur more to the left, or toward the spokes. Less inner wire tension tends to move the derailleur to the right. The inner wire tension will not stop the derailleur at its extreme limits. The H-limit screw stops the derailleur at its right most setting, and the L-limit screw stops the derailleur at its left most setting. (Shimano® or "Low-Normal" derailleur are a bit different, see procedures at the bottom.)

   Modern indexing shift levers use dwell, which is a hesitation between movements in the lever. These hesitations are timed to match the movements of the derailleur and the spacing in the rear sprockets. The design of some derailleur and shift lever brands requires more of a push (or twist) of the lever to complete the shift. The amount of extra push or twist is not consistent between manufacturers and each rider must learn the particular attributes of his or her system.

   Changes to inner wire tension are made at the adjusting barrel. Adjusting barrels may be located either at the rear derailleur or at the shift lever. The goal of adjusting the indexing is to find the tightest inner wire tension setting that will allow good shifting to the gears normally used. This will allow the longest lasting indexing adjustment as the system wears and the cable system stretches with use. To find the tightest inner wire setting, you will purposely make the setting too tight then relax tension slightly. There are two basic symptoms for a "too tight" inner wire. These are a rattling noise from the chain rubbing against the next cog inward, and a slow or hesitant outward shift. These are symptoms for rear derailleurs that sit outward when inner wire tension is released.

   NOTE: If the cable inner wire is not correctly routed into the derailleur pinch bolt, a good indexing setting may not be possible. The wire should leave the barrel adjuster and travel straight to the pinch mechanism. The upper image is correctly routed, while the lower image shows incorrect routing.

   

   
   

   Index Setting

   1. Set limit screws (if not already done).
   2. Shift chain to outermost rear sprocket (smallest). Shift chain to outermost (largest) chainring in front.
   3. Test initial inner wire tension. Pedal a normal cadence and shift rear derailleur with one click on lever. Use care to only move lever one position. If derailleur moves one sprocket, tension is adequate.
   4. If derailleur fails to shift one sprocket, inner wire may be too slack. Turn barrel adjuster fully into derailleur body (or shift lever) then turn counter clockwise two turns to allow for index adjustments. Loosen inner wire pinch bolt and gently pull on inner wire with fourth hand tool or pliers to remove slack. Tighten inner wire pinch bolt.
   5. If derailleur will not shift one sprocket after removing slack in "d", return lever back to outermost sprocket position and increase inner wire tension by turning barrel adjuster counter-clockwise 1/4 turn and attempt shift again.
   6. Shift to second sprocket in rear. Pedal and increase inner wire tension by continuing to turn adjusting barrel counter-clockwise until a definite rattling is heard. Rattle is from chain scrapping against next sprocket.
   7. Once a too-tight rattle is achieved, turn barrel adjuster 1/4 turn clockwise, to release inner wire tension, and pedal again. Listen and look for signs of scraping or rattling. Continue turning barrel adjuster 1/4 turn clockwise at a time until rattle disappears.
   8. Shift derailleur one sprocket inward at a time, listening for signs of rattle, indicating a too tight inner wire. Turn adjusting barrel 1/4 turn clockwise to eliminate rattle. Note: Do not attempt shift to largest rear sprocket while in largest front sprocket. This gear is normally not used and adjusting tension to this shift may compromise other commonly used gears.
   9. Shift to innermost (smallest) chainring and check gears again. If no rattling is present, index adjustment is done.
   
   

   Shimano "Rapid Rise" or "Low-Normal" Derailleur Indexing Adjustment

   Shimano "rapid rise" or "Low-Normal" derailleurs use a return spring that puts the derailleur under the innermost rear sprocket when the inner wire tension is released. As with other indexing derailleurs, the inner wire tension should be set as tight as possible with good shifting. However, the symptoms of a too-tight setting are different, which for "Low-Normal" systems are when the derailleur shifts outward slowly, or a there is a rattle from the upper pulley being aligned too far outward. Look underneath the rear sprocket at the alignment of the upper pulley when there is a rattle to see if this is the cause.

   1. Shift chain to middle ring in front and innermost sprocket in back.
   2. Pedal and shift lever one position.
   3. Pedal and turn barrel adjuster counter-clockwise to tighten inner wire tension until chain begins to shift outward.
   4. Turn barrel adjuster clockwise 1/4 turn until chain runs smoothly on second cog.
   5. Shift outward one sprocket at a time trying each gear. Turn barrel adjuster 1/4 turn clockwise if too tight symptoms occur.
   6. Shift to all other normal gear combinations and test adjustment.

   NOTE: The indexing procedure here assumes that there are no unusual problems, such as bent derailleurs, bent derailleur hangers or excess inner wire friction from dirt in the housing. Additionally, manufacturers design shift levers and drive train components to work within their system. Mixing brands within the drive train may lead to poor shifting. This is referred to as an compatibility problem.

SHIFT LEVERS

Useful Tools and Supplies

• Repair Stand.
• Hex wrenches.

This article will discuss the shift wire (cable) installation. See also related article discussing housing length.

SRAM® Shift Levers

SRAM® shift levers are commonly called Grip-Shift. The levers mount to the handlebar between the brake levers and the grips. The lever may be rotated on the bar so the cable housing exits without interference.

There have been different generations of the Grip-Shift levers, and wire installation of the shift wire can vary. Inspect the lever an access hole or cover. Shift the lever to the most relaxed wire position. Remove the cover. Disconnect the wire from the derailleur. Pull housing away from lever and push bare wire to remove wire from lever.

Remove cover to expose wire end.

Some models may have a small set screw over the wire end. Use a hex wrench to remove this screw.

Remove set screw.

On some SRAM® models the wire end may be held in the lever by a small clip. Usea small screwdriver to pry back this clip, and then push the wire end out.

Pry clip back to access wire end.

Feed the wire in and out through access hole.

Shimano® STI Shift Levers

Shimano® levers have had different generations that vary in wire attachment. There may be a cover on the lever body that must be removed. There are both pry-out type covers and threaded type covers. Remove cover, if any. Shift the lever to the most relaxed cable position. Detach wire from derailleur. Pull housing away from lever and push the wire outward from the lever.

XTR® and XT® levers may also have a cover plate. Use a #1 or #0 cross tipped (Phillps) screwdriver to remove two screws. The screws are quite small, so use care when removing. It is helpful to rotate the bike upside down until the screw heads are pointing upward.

The wire end is held in a fitting that allows easy removal. There is a slot in the adjusting barrel and the body. Rotate the adjusting barrel so the slots align, and lift the wire outward. Install new wire into fiting, and into adjusting barrel. Install cover plate and screws. Tighten screws until snug, but do not over tighten.

Shimano® XTR Rapid Rise Integrated Shifter

The integrated rapid rise shifter uses a cover that must be removed. Use a small cross tip (Phillips) screwdriver to remove the small screw holding the cable cover.

Remove cable cover screw.

It is not necesary to remove any other screw, remove only on the cover screw.

Push gently but firmly outward on cable cover.

The cover plate may be a snug fit. Push outward only, do not ply forward to remove.

 

The shift wire head sits inside a carrier. Articluate the shift lever to gain access to the wire end, and pry up and out. Install a new wire.

Replace cable cover by sliding it into place. Replace cable cover screw.

 

Shimano® Revo Shifter

The Revo Shifter is a twist type shifter. The lever must be partly dismantled to remove the shift wire. The lever is secured to the handlebar with a clamping screw under the lever.

The Revo Shifter

Shift the lever so the cable is in the most relaxed position. Rotate the lever toward the front, as seen from the rider's point of view. Detatch the cable from the derailleur and pull the housing from the lever body.

There is small screw holding the cable cover to the lever body. The screw is located on top of the shifter body toward the front of the bike. It will be inboard of the twisting part of the lever. Use a small Phillips screwdriver such as the SD-0 to remove.

Remove cover screw.

The cover is plastic, use care, and do nothing drastic. The front of the cover will be free to lift, but do not pull up of the front at this time, it may break the cover. The rear of the cover is held by an internal boss fitted to the lever body. Pry with a blade or narrow tool at the back of the lever at the split. Lift the back of the cover upward.

Pry at back of cover to remove.

Lever is removed to expose cable end.

 

Use a small pointed tool to bend cable head out of socket in lever. Pull old wire and remove it from lever. Install new wire into lever fitting and through wire routing in lever body. Inspect that wire follows routing before installing cover and securing cover screw.

 

Drop Bar Intergrted Brake-Shift Lever Derailleur Wire Installation

The derailleur wire end attaches to the shift lever by fitting through a small socket called the derailleur wire anchor pivot. The wire anchor pivot is sometimes difficult to see. Begin by shifting to the most lever relaxed wire position. Feed the cut end of the wire through the anchor pivot, and pull it fully through unit the head engages the pivot.

Derailleur wire attachment is on the outside of each Shimano® STI road lever.


Campangolo® derailleur wires access from the underside of the lever body.

SHIFT HOUSING LENGTH

Typical Tools and Supplies

• Cable Cutter:CN-10
• Brake housing and cables as needed
• Shift housing (compressionless) and cables as needed
• Housing end caps (ferrules) as needed
• Light lubricant
• Mill file (for brake housing as needed). Bench grinder or dermel also useable.
• Hex wrenches for cable binder bolts

This article will discuss the cutting and sizing of both brake and derailleur housing. See also related articles on brake and shift levers.

The Park Tool CN-10 Cable Cutter is designed to cut multi-strand wires such as gear and brake cable, brake housing, and compressionless gear housing. Compressionless shift housing uses many inner support wires running longitudinally with the inner plastic liner. Compressionless shift housing is intended for shifting systems only, not braking. Brake housing is commonly made of a wire wound around a plastic liner. Use ends caps or ferules at the ends of housing when ever possible. There is also available a woven or braided-type of housing that is may be used for both brake housing and shift housing. It is recommended to lubricate inside the housing or the cable is installed.

The jaws of the cable cutter surround and then shear the material. Using plain diagonal cutters can simply flatten and smash cables. As with all cutting tools, it is recommended to wear eye protection.

Grab and hold the cable or housing close to the jaws. Use care not to cut your fingers. Hold cable or housing perpendicular to jaws and squeeze levers quickly for a clean cut, as seen below.

After cutting the compressionless gear housing, inspect the end to see if it flattened a bit. Use the crimper section of the CN-10 to open up the housing and inner liner before installing an end cap and cable. You can also use the crimper section cutter to crimp on a cable end cap, as seen below.

How Long Should Housing Be?

Brake and gear housing allows the cable wire to be routed around bends and connects the levers to the frame stops. The less the drag on the cables, the better for the shifting and braking. Too short of housing will cause it to kink and bind, making even more friction. As a rule of thumb, try to size the housing so it is as short as possible but it still enters the stops and barrel adjusters in a straight approach. For the rear derailleur housing, note especially how the housing enters the barrel adjuster.

In the left image above, the housing bends immediately upon leaving the barrel adjuster. This can actually bend the housing end cap. The image to the right shows how longer housing in this case allows the housing to enter straight.

The left image above is a typical new bike housing length. The housing bends and kinks as it enters the barrel adjuster. The image to the right shows longer housing allowing a straight entry into the barrel adjuster.

The image above shows brake and shift housing which is much too long. The housing could be shortened and still have a smooth, straight approach to the levers and housing stops.

The routing of housing may affect the length. Typically the front derailleur shift housing is run on the left side of the frame, while the rear derailleur shift housing is run on the right. This may at time cause unnecessary bending in the housing. In some cases, it is possible to "cross over" the housing, running the front shifter to the right side stop, and the rear shifter to the left side stop. It will then be necessary to again cross the cable. Consider this option, but if the cable ends up rubbing the frame, it is not a good idea. There may be some light rubbing between cables, but this would result in less friction than poorly routed housing.

Shift lever housing that is too long. Housing passes center line of bike, then must bend back to housing stops.

Shift housing is crossed over at headtube, and crossed again on downtube. Arc of housing is much smoother than black housing in example of too long housing.

Cutting Brake Housing

Brake housing is typically made of single strand flat wire wrapped around an inner plastic tube. This housing may be cut with the CN-10, or diagonal cutting pliers. Because of the design of the housing wire, it is not always possible to get a flat, clean cut. It is best to finish any burr with a file. Lightly grinding the end will also improve the housing and reduce friction.NOTE: Compressionless housing does not require finishing.

Adjustment of the Park Tool Cable Cutter

As a cable cutter wears, it may require readjustment for best cutting results. See Cable Cutter Adjustment is the cutter is not performing well.

REAR DERAILLEUR HANGER ALIGNMENT

Useful Tools and Supplies

• Repair Stand, holds bike for checking and alignmnet.
• DAG-1 Derailleur Alignment Gauge
• Hex wrenches

This article will discuss derailleur hanger alignment and use of the Derailleur Alignment Gauge DAG-1.

A misaligned derailleur hanger will often result in poor shifting performance. A common cause of a misaligned hanger is from the bike falling over to the right side. This pushes the derailelleur body inward, bending the hanger.

It is often possible to repeatedly re-bend many derailleur hangers. This is because there is very little stress from riding the bike or shifting gears. As a rule of thumb, if a hanger survives a repair by bending, it will survive use. However, there are some hangers that do not repair well. Extremely thick hangers and titanium hangers are difficult and sometimes impossible to repair. Bolt-on type hangers that are replaceable are alignable. However, these types of hangers can be tricky to align if the clamping design of the hanger to the frame is less than adequate It is common for these type of replaceable hanger to move in the mount.

After aligning and correcting the derailleur hanger, it will be necessary to check all rear derailleur adjustment, including limit screw and index settings. For rear derailleur adjustments see Rear Derailleur Adjustment.

Procedure for Derailleur Hanger Alignment

Note: Newer DAG-1 models will now come with 2 o-rings for the slider. These will help prevent slider from falling out and can be used as markers when racks or fenders prevent full DAG-1 rotation. This procedure will be described at the end of this article.

Begin by mounting the bike in a repair stand with the wheels level as the bike would appear on flat ground. Check that the rear wheel that is mounted straight in the frame. The wheel does not need to be dished or true for use of the tool. Remove rear derailleur. Install DAG-1 and tighten handle. NOTE: Do not use the DAG-1 threads as a "chaser" of bad derailleur hanger threads. Chase and clean the threads using the TAP-10.

Rotate the arm toward the left side of rim, at the "9:00 o'clock" position. Rotate the tire valve to the 9:00 position. Use this point on the rim as a constant reference when checking the hanger. By checking the same point on the rim, wheel trueness or dish will not affect alignment.

Loosen the sliding gauger knob and move the sliding gauge to contact rim and secure knob.

Slide gauge braket torward hub before rotating arm. This prevents gauge from begin forced against rim.

Rotate DAG-1 and rotate rim valve 180 degrees to the 3:00 position. Slide indicator toward rim to same point near valve.

There are 3 possible results:

• Conition A: The gauge is barely touching the rim. In this case the hanger is aligned horizontally.

  

• Condition B: The pointer is away from the rim some distance. The hanger is misaligned.

  

• Condition C: The pointer strikes inside the rim, indicating a misaligned hanger.

  

  It is easier to determine the error by seeing the gap between rim and gauge. In condition B, re-set tool at the 9:00 position and rotate back to the 3:00 position. There will be a gap between rim and gauge.

When bending hanger, it is best to bend small in amounts and re-check. The amount of error is actually one-half the gap between gauge and rim. As the gap is closed, it increases at the reference point 180 degrees away. Bend a bit, re-check both side, and then re-bend a bit more. Generally, it is best by having the DAG-1 arm next to the chainstay. This allows you to use the stay for leverage and control the amount of bending either inward or out. Repeat bending and checking until the gap is less then 4mm. Use a 4mm hex wrench as a "go-no go" gauge.

After getting the horizontal aligned, check and aligned, move on to check the 6:00 and 12:00 position. Set gauge to 6:00 position, then check at 12:00 position.

Again, bend only one-half the amount of gap. Reset pointer at each bending of hanger. When gap is less then 4mm, keep same the setting and check 3:00 position. If three points 90 degrees apart are within 4mm, hanger is aligned. Continue aligning as necessary.

Rack, Fender, or Other Interference

There may be fenders, racks or other situations where it the gauge is blocked from rotating to the various points. The newer DAG-1 models use two o-rings to hold the gauge in place. This helps prevent loose of the gauge. Additionally, the o-rings can be used as markers, allowing the gauge position to be accurately referenced, the gauge moved to pass the obstacle, and then the gauge returned to its original position. Below is an example of a bike with a rack the prevents DAG-1 rotation.

Push outer o-ring to slider. This marks the position of the gauge relative to the slider.

When the gauge cannot pass by a frame stay, fender stay, or rack, loosen gauge knob and pull gauge back to clear.

Return the gauge so the o-ring is back in the original position. In the image below, the gauge is contacting the rim, but the o-ring is positioned away from the slider. In this situation, the gauge would be resting inside the rim. There will be situations where the o-ring contacts the slider, but there will be a gap between rim and gauge end.

CUTTING CABLE HOUSING

How do I cut cables and housing?

Typical Tools and Supplies:

• Cable Cutter: CN-10
• Brake housing and cables as needed
• Shift housing (compressionless) and cables as needed
• Housing end caps (ferrules) as needed
• Light lubricant
• Mill file (for brake housing as needed). Bench grinder or dermel also useable.
• Hex wrenches for cable binder bolts

This article will discuss the cutting and sizing of both brake and derailleur housing. See also related article Brake and Shift levers.

The Park Tool CN-10 is designed to cut multi-strand wires such as gear and brake cable, brake housing, and compressionless gear housing. Compressionless shift housing uses many inner support wires running longitudinally with the inner plastic liner. Compressionless shift housing is intended for shifting systems only, not braking. Brake housing is made of a wire wound around a plastic liner. Use ends caps or ferules at the ends of housing when ever possible. It is recommended to lubricate inside the housing or the cable is installed.

The jaws of the cable cutter surround and then sheer the material. Using plain diagonal cutters can simply flatten and smash cables. As with all cutting tools, it is recommended to wear eye protection.

Grab and hold the cable or housing close to the jaws. Use care not to cut your fingers. Hold cable or housing perpendicular to jaws and squeeze levers quickly for a clean cut, as seen below.

After cutting the compressionless gear housing, inspect the end to see if it flattened a bit. Use the crimper section of the CN-10 or CN-4 to open up the housing and inner liner before installing an end cap and cable. You can also use the crimper section cutter to crimp on a cable end cap, as seen below.

How Long Should Housing Be?

Brake and gear housing allows the cable wire to be routed around bends and connects the levers to the frame stops. The less the drag on the cables, the better for the shifting and braking. Too short of housing will cause it to kink and bind, making even more friction. As a rule of thumb, try to size the housing so it is as short as possible but it still enters the stops and barrel adjusters in a straight approach. For the rear derailleur housing, note especially how the housing enters the barrel adjuster.

In the image above, the housing bends immediately upon leaving the barrel adjuster. This can actually bend the housing end cap. The image to the right shows how longer housing in this case allows the housing to enter straight.

The image above is a typical new bike housing length. The housing bends and kinks as it enters the barrel adjuster. The image to the right shows longer housing allowing a straight entry into the barrel adjuster.

The image above shows brake and shift housing which is much too long. The housing could be shortened and still have a smooth, straight approach to the levers and housing stops.

The routing of housing may affect the length. Typically the front derailleur shift housing is run on the left side of the frame, while the rear derailleur shift housing is run on the right. This may at time cause unnecessary bending in the housing. In some cases, it is possible to "cross over" the housing, running the front shifter to the right side stop, and the rear shifter to the left side stop. It will then be necessary to again cross the cable. Consider this option, but if the cable ends up rubbing the frame, it is not a good idea. There may be some light rubbing between cables, but this would result in less friction than poorly routed housing.

Shift lever housing that is too long. Housing passes center line of bike, then must bend back to housing stops.

Shift housing is crossed over at headtube, and crossed again on downtube. Arc of housing is much smoother than black housing in example of too long housing.

Cutting Brake Housing

Brake housing is typically made of single strand flat wire wrapped around an inner plastic tube. This housing may be cut with the CN-10, CN-4, or diagonal pliers. Because of the design of the housing wire, it is not always possible to get a flat, clean cut. It is best to finish any burr with a file. Lightly grinding the end will also improve the housing and reduce friction. NOTE: Compressionless housing does not require finishing.

Adjustment of the CN-4

As a cable cutter wears, it may require readjustment for best cutting results. Grab the handles and wiggle them against the axis of the thread. If there is play between handles, turn locknut counterclockwise to loosen nut, turn bolt head clockwise slightly to tighten adjustment, and retighten locknut. Repeat adjustments as needed until tool cuts cable cleanly. If handles bind, turn locknut counterclockwise to loosen nut, turn bolt head counterclockwise slightly to tighten adjustment, then retighten locking nut. Repeat adjustments as needed until tool cuts cable cleanly.

BAR END SHIFTER SERVICE

This article will discuss bar end shifters. These are derailleur shift levers mounted to the ends of time trial or triathlon handlebars (Figure 1). They are also found on drop style handlebars (Figure 2).

Figure 1

Bar end shifters on a time trial handlebar.

Figure 2
Bar end shifters on drop style bars.

 

The bar end shifters mount internally to the handlebar using an expansion plug. Handlebars typically must have an inside diameter of approximately 19-21mm. The shifter body and bolt are made with a cone shaped end that push into a set of wedges (Figure 3). The wedges then expand and tighten inside handlebar.

 

Figure 3
The component parts of the bar end shifter.

 

To access the mounting bolt, it is necessary to remove the shift lever. Insert a 6mm hex wrench through the lever body and into the back of the mount bolt. The hex wrench fits into the back of the mounting bolt. Turning bolt clockwise as viewed from end of lever frees bolt from the internal wedges (Figure 4).

Figure 4
Securing the lever body.

 

To secure body, turn hex wrench counter-clockwise. This turn bolt to tighten it into the wedges inside of handlebar. When working with bar end levers, always remember the body acts as the nut. The head of the bolt is inside the lever, and the hex wrench is fitting into the end of this bolt (Figure 5).

Figure 5
Hex wrench turn cone-shaped mounting bolt.

 

After securing shift lever body to handlebar, assemble shift lever parts to body and secure lever screw with screwdriver (Figure 6).

Figure 6
Secure shift lever parts to lever body.

 

Install gear wire through lever and into housing. Housing must fully seat into lever body. Secure housing to handlebars with tape. This can later be covered with handlebar tape as desired (Figure 7).

 

Figure 7
Bar end shifter mounted to forward-facing aero bar extensions.

Handlebar tape may then be wrapped over the housing (Figure 8).

Figure 8
Bar end shifter housing under handlebar tape on a drop handlebar.

 

Shift wire may be removed or install with the lever mounted in the bar. Loose wire pinch bolt and free wire. Pull wire from lever (Figure 9).

Figure 9
Remove or install derailleur wire from bar end shifter as necessary.

REAR DERAILLEUR OVERHAUL

Rear Derailleur Overhaul and Pulley Cage Tension

Typical Tools and Supplies Needed:

• Hex wrenches
• Screw drivers, narrow straight blade and #2 Phillips
• Work tray for small parts
• Seal pick (optional)
• Bench vise (optional)
• Grease: Park PolyLube®
• Degreaser for cleaning small parts CB-2
• Light lubricant such as CL-1 Chain Lube

This article will discuss the overhaul of Shimano® and Campagnolo® rear derailleurs, which share many service features. The internal overhaul of the SRAM® X.0 rear derailleur will also be discussed. The Mavic® Mektronic will also be reviewed, although user service is limited. It should be noted that every model of every brand cannot be overhauled. See also related articles:

• Rear derailleur- limit screws and index settings
• Front derailleur- limits screws and index settings
• Wire cable-sizing and cutting inner wire cable and housing (gear and brake)
• Brake and Shift levers
• Rear derailleur- bent hanger

Some rear derailleur models allow the internal servicing in order to clean and lubricate. This often improves performance by removing dirt from pivots. Additionally, some models allow for the changes to the pulley cage tension spring. There are also after-market top pivot "break-away" bolts, which may be installed in place of the orgininal mounting bolt.

It will be useful to have a note pad and pen to help you remember correct orientation of parts. Sketch any parts that seem unfamiliar, or use a digital camera for the same purpose. Have some wire ties or twine on hand to help tie parts in their correct orientation as they come apart.

Begin by removing the rear derailleur from the bike. Loosen inner wire pinch bolt and pull inner wire from adjusting barrel. Remove the chain if it has a master-link. Loosen derailleur mounting bolt and remove derailleur from bike.

For bicycle chains with no master-link, the cage may be dismantled, which allows the chain to stay together. Note and record any marking distinguishing upper and lower pulley. Also note the orientation of the cage. Loosen and remove both derailleur pulley bolts. Remove the cage and chain from the derailleur.

The derailleur may contain a tension spring in the upper pivot, at the mounting bolt. This spring controls the angle of the derailleur body. The mounting bolt spring and cage pivot spring oppose one another. Changing tension in the upper pivot relative to the lower pivot will move the derailleur body and upper pulley wheel relative to the cogs. Generally, it is desireable to have the upper pulley ride close to the cogs. Check the cog to pulley position when the chain is on the largest rear cog and the smallest front ring. If the largest cog is actually rubbing against the upper pulley, move the derailleur body back to move the pulley away. For derailleurs with the spring in the upper pulley, increase the spring tension by tightening the "B" screw, found in adjacent to the top bolt. If there is a large gap between pulley and cog, the screw should be loosened.

Generally, the upper pivot spring tension should not be increased to solve the problem of chain slap or chain suck. Chain slap may be reduced slightly by this procedure, but chain suck is typically the result or worn or bent chainring teeth, or a worn chain. Increasing the derailleur cage tension tends to have a marginal effect of chain suck. For chain slap, it is preferable to increase the tension of the pulley cage. There are limits to this procedure, as the upper mounting bolt spring tension opposes the cage spring tension. Increasing the cage spring tension will require an increase in the mounting bolt spring tension. If the derailleur B-screw is at it's limit, it is not adviseable to increase cage tension.

Campagnolo® derailleurs locate the B-screw in lower cage pivot. The upper spring tension is fixed. Tightening the B-screw will increase tension of the cage, allowing the pulley to move toward the cogs. Loosening the B-screw will decreases spring tension at the cage, allowing the upper pulley to move away from cogs. The screw turns a toothed plate that holds the spring end.

Prodedure for Derailleur Overhaul (most models of Shimano® and Campagnolo®)

1. Use a thin tipped screwdriver to pry off the C-clip on the back side of the derailleur mounting bolt. Work over a table to avoid loosing parts. Maintain pressure on the B-screw plate against the body while removing the clip. This helps prevent parts from flying off as spring tension is released.

   

2. Remove body-screw plate from derailleur body. Note and write down orientation of parts. Note especially any seals and the direction of seal lips.

   

   

3. Remove the lower cage from the derailleur body. There are several different systems of cage attachment. Many models from Shimano® use a screw under the body, called the P-screw. This screw holds a stud mounted to the pulley cage. To prevent premature release of cage spring tension, hold derailleur cage firmly to derailleur body and remove this screw using hex wrench.

   

4. Alternatively, there may be a set screw in the derailleur cage that acts as a stop. Pivot cage away from stop, and remove set screw, then allow derailleur to unwind. Note direction cage unwinds for re-assembly.

   

5. For P-screw type derailleurs, hold both derailleur body and derailleur cage. Pull cage away from body and allow cage to unwind. Note direction the cage unwinds.

   

6. The derailleur cage may be held to the body with a pivot bolt. The bolt head may face toward outside, away from the spokes, or it may face inside, facing the spokes. Loosen and remove bolt. Note and record any washers or seals found on bolt or on cage.

   

7. As cage is removed from body, make note of the spring hole in the derailleur cage and body. There are commonly two or more hole choices. New derailleurs are typically assembled with the spring in the hole that allows the most relaxed postion of the spring. If more cage tension is desired, the spring end can be installed in the other hole.

   

8. Remove spring from inside derailleur body. Note especially the direction of the coil ends. The smaller end tends to face toward the derailleur cage, and the larger end goes into the derailleur body. There is commonly a seal as well. Note direction of lip.

   

9. If derailleur cage is still together, loosen and remove one at a time each pulley bolt. It is common for the upper and lower pulleys to be different. Do not mix parts from upper and lower pulleys. Upper pulley may be labeled as "G" pulley, or simply "upper".

   

   

10. Note parts orientation of cover plates, seals, and bushing. Use a wire or string to tie these parts together in the correct orientation.

    

11. Some pulley have have a cartridge type bearing. Use a seal pick to carefully lift the seal from the inside edge.

    

12. Clean all parts is a degrease and dry. Use compressed air if possible, but do not allow bearings to spin.
13. Use a light lubricant on pulley bushings and seals. Assemble pulleys into cage in the same orientation as they were dissassembled. Remember to refer to your notes on orientation. Install and tighten pulley bolts to about 30 inch-pounds. Use of a mild threadlocker is recommended.
14. Cover both springs heavily with grease.
15. Install cage spring into derailleur body, with smaller tapered end of spring facing outward toward cage. Be sure to engage spring into spring hole inside body. Place dust seal over derailleur body as it came off.
16. Engage cage spring into derailleur cage and body. Again refer to notes from disassembly. Changing spring hole location will change tension. In the image below, spring is in most relaxed position. Seen from this orientation, cage will be rotated counter-clockwise for working tension.

    

17. In the image below, the spring is engaged in the higher tension spring. Notice cage must now be wind futher counter-clockwise, adding to spring tension.

    

18. Press cage into derailleur body and begin to rotate derailleur cage toward back of derailleur. It is important to always wrap the spring tighter in the same direction as the coil.

    

19. Looking at the back side of the derailleur (opposite side of brand name) rotate cage clockwise to tension spring.

    

20. For P-screw type derailleurs, cage stop and derailleur body stop must clear. Pull slighlty outward on cage and allow the two stops to pass. Push cage fully into derailleur body once stops are cleared.

    

21. For bolt type pivots, rotate cage until you can access stop screw.

    

22. For P-screw type, re-install set screw into derailleur body.

    

23. Mounting bolt spring can be difficult to engage and tension. It is useful to mount a hex wrench with the short "L" facing upward in a vise. The vise and wrench act as a holder and frees up your hands.
24. Install spring into body in same orientation as it came apart. Note direction of spring coils, which will indicate the direction of tensioning spring. Place dust seal over spring. Engage body tension plate on spring. Press plate fully down to see if plate will fully engage system.
25. Using needle nose pliers, grab body angle screw.

    

26. Again, tension spring with direction of wrap. Upper pivot springs wrap counter-clockwise. Rotate plate counter-clockwise to tension spring. Pull plate upward enough to clear stop tabs on each.

    

27. Push downward on plate and hold pressure downward before installing C-clip.

    

28. Install C-clip onto mounting bolt. Use needle nose pliers to fully engage C-clip.

    

    

SRAM® X.0 Derailleurs

The X.0 derailleur may be overhauled at the lower cage pivot. The mounting bolt has no spring, and it is best to leave this bolt in place. No lubrication of the mounting bolt pivot is recommended.

The SRAM® parallelogram spring is very strong. It is possible to use a zip tie to hold the derailleur body away from the cage, making it easier to work with the cage. Feed a zip tie through the body below the cable stop, and through the cable guide. Pull the cage away from the body as if shifting toward larger cogs, and secure the zip tie to hold the body.

Lower Pivot Overhaul Procedure

1. Rotate cage to expose the cage stop screw. Loosen and remove the stop screw. Cage will now rotate back past the stop screw position.

   

2. Allow cage to rotate forward and relieve spring tension. Note position of cage to derailleur body in this relaxed position.
3. The pulley cage is held to the body with a stud pressed into the cage. The stud has a "D-fitting", that mates with a D-shape recess in the body. The body must be rotated to one position only before the cage can be removed.

   

4. There are three tension options in the cage, as seen in image above. The middle spring hole is used on new derailleurs. To decrease chain slap, increase spring tension by moving spring to left hole of the three choices, as seen from the stud side.
5. After removing the pulley cage, loosen and remove pulley bolts. Pulleys use a cartridge bearing, use care when removing seal.

   

6. Clean all parts in a degreaser. Pack grease into seals of pulleys and re-install seals. Pack grease into cage pivot spring.
7. Assemble pulley wheels into cage and install pulley bolts. A mild threadlocker is recommended on the threads. Spin pulleys to check proper for alignment after securing bolts.
8. Place spring into body of derailleur in same orientation as it was removed. Engage spring end into desired cage hole.
9. Push cage to derailleur body. Cage must rotate to allow "D" fitting to engage into body. Approximate position of cage to body for "D" fitting alignment is shown below.

   

10. Rotate cage counter-clockwise as seen from orientation of image above. Install and secure cage stop screw. Remove zip tie. Derailleur is ready to be installed.

Mavic® Mektronic

The Mavic® Mektronic derailleur has many internal parts, including electronical parts. There are very few user serviceable parts. The pulley wheels can be brushed clean with a dry bush. Avoid using solvents during cleaning.

There is a boot covering the arm that extends to shift the pulley cage. Use only a soapy water on a rag to wipe this clean. Use care not get water or soap into the working mechanism.

The derailleur uses a selenoid initiate the shift. It is activated by a battery. The battery cover is removed using a 1-Euro coin (substitute US twenty-five cent piece).

The derailleur B-screw is located at the top mounting bolt. There is a spring in this pivot, but it is recommend the pivot not be disamantled.

Derailleur Wear

The rear derailleur will become worn with use and abuse. As the derailleur wears, it will develop play at all pivot points. Grab the cage at the lower pulley of a new derailleur while mounted to a bike and wiggle it side to side. Do the same test on an old model to compare. Replace derailleur when this play becomes significant.

The derailleur pulleys will wear and eventually require replacement. The teeth will thin and become pointed, especially the lower pulley. Worn pulleys will not be able to hold or guide the chain as well as newer pulleys, and shifting performance will suffer. In the image below, three pulleys are shown in progression of wear. Pulley bearings or bushings will also wear and create more play in the pulley.

CHAIN LINE

Typical Tools and Supplies:

• Repair Stand, holds bike secure for easy work.
• CLG-2 chainline gauge (discontinued)
• Caliper and feeler gauges

This article with discuss the use of the CLG-2 chainline Gauge and the concept of chainline. Also see related article on frame alignment.

Chainline and Shifting Issues

There are two related aspects to the term "chainline". First, chainline can be defined as the position of the cogs or chainrings relative to the center line of the bike. The bike center line is an imaginary plane running front to rear through the middle of the bike. For example, a front crankset and/or front derailleur might be desgined to have a chainline of 47.5mm. This means it will work best when the middle of the crankset is 47.5mm from the middle to the bike center line.

Chainline can also refer to the relative position of the front and rear cogs to each other, without regard to the bike centerline. This is called "effective chainline". A bike may have the crankset inward or outward some distance of the rear cogset center.

Drive train manufacturers do not generally specify "perfect" or center-to-center alignment between rear and front cogsets. The front chainrings may be a few millimeters outward relative of the rear cogs. Additionally, drive train manufacturers do not generally consider all gear combinations to be "useable". For example, a so-called "27-speed" bike has three rings in front and 9 cogs in the rear. However, it is likely when the chain is on the smallest cog in front and possibly 2 or 3 of the smallest cog in back, the chain will rub the side of the middle ring. This should not necessarily be considered a "chainline" error. If this bottom bracket length were increased until there was not rubbing in these combinations, there may be poor shifting in other gear combinations, such as the largest ring and the larger rear cogs. These combinations are commonly called "cross-chaining". Bicycle chains are quite flexible, and will work well at various other then perfectly straight. Cross-chaining is primarily an issue when the chain hits the front rings. As a simple rule, if a gear combination causes a rubbing problem, avoid that gear.

Rear Cogs to Front Rings- Effective Chainline

The CLG-2 Chain Line Gauge helps determine effective chainline of the front and rear gears. The tool references off the rear sprocket center and extends this line forward toward the front rings.

To use the CLG-2, begin by checking the centering of rear wheel in frame. It should be centered between chain stays. Begin by getting the chain out of the way. Shift chain to smallest freewheel cog, and the innermost chainring (smallest ring). It is sometimes necessary to drop the chain off the front chainring onto the bottom bracket so it does not strike to CLG-2.

For odd numbered rear cogs (5,7,9-speeds), clamp the CLG-2 over middle cog. Snug the knob and do not over tighten.

For even numbered rear cogs (6,8,10-speed), the middle of freewheel is a space, with the same number of cogs on either side. Clamp the CLG-2 so the main bar is falling in the middle space. The tool will clamp the cog inboard of this middle space (4th cog of 6 speeds, 5th cog of 8 speeds, 6th cog of 10 speeds.) Snug knob and do not over tighten.

Extend sliding gauge close to chainring, but do not allow contact with chainrings or the front derailleur. Most freewheels and freehubs have play. After clamping gauge, move CLG-2 end side to side, and hold end to center of play for most accurate reading.

Reading the CLG-2

Odd Numbered Cogs
Because the CLG-2 clamps over the center cog of odd-numbered freewheel (5, 7, 9), the black sliding gauge represents the middle of the rear cog set. The center of sliding gauge may or may not point to center of chainring set. If the sliding gauge is not pointing to the middle of the front crankset, estimate the amount to either side it is off.

NOTE: Most component manufacturers do not design drive trains for "perfect" or center-to-center alignment. It is common for the chainrings to be slightly outward of the rear cog chainline by as much as several millimeters.

Even Numbered Cog Sets
For even numbered rear cog sets the CLG-2 clamps over the cog inboard of the cog set center. The main chrome arm, not the black sliding gauge represents the rear cog set center. It is therefore necessary to estimate the center where the end of the gauge points at the front chainrings.

For three ring cranksets, the sliding gauge should point inboard, or just to the left from the rider's point of view, of the middle ring.

For double ring cranksets, the black sliding gauge should point just outboard, to the right, of the inner ring.

Front Chainring Position and Bottom Bracket Length

The front chainrings should to be within a certain distance of the bicycle center line. If the rings are too far in or too far out from the frame, the front derilleur may not shifting properly. The position of the front rings is in large part determined by the length of the bottom bracket spindle. Many bottom bracket spindles are specified with a certain chainline number, such as 47.5mm or 50mm. Spindles are also specified by spindle length, which is simply the length end-to-end. As an example, a particular bottom bracket may be specified wtih a 47.5mm chainline, and a 113 spindle length. A crank arm designed for use with this spindle will have the middle of the crankset 47.5mm from the bike center line.

Manufacturers often specify both spindle length and chainline, as both concepts are related. For example, cartridge bottom brackets may come in various spindle lengths. For example, the 118mm is 5mm longer than the 113mm bottom bracket. The chainline of the 118mm of this particular model 50mm. The 113 has a chainline of 47.5mm, or 2.5mm smaller. This is because in this case the 5mm shorter spindle is split between evenly between the left and right sides. However, a different model of spindle is available in 109.5mm or 118.5mm lengths. The difference in spindle length is 9mm. The chainline of the 109.5mm is 43.5, and the chainline of the 118.5 is 45mm. The difference between the spindles in not even split between the two different lengths.

Often, the combination of crankarm and spindle determine chainline. This is especially the case for the square-type spindles because the exact fit inside the square fitting of crankarms varies between brands and even between arms of the same model. It is sometimes necessary to simply guess at a bottom bracket for a bike, install the crank and then measure the results. The results will then let you know if a longer or shorter chainline spindle should be installed.

It is often useful to know the existing position of the front rings relative to the bike center plane. However, it is difficult to take a direct measurement from the center of the bike to the center of the front rings. It is necessary to take several measurements, and then determine chainline by adding or subracting the measurements.

The accuracy of measuring for chainline is limited by the accuracy of the frame. If the bottom bracket or frame tubing is not centered, the chainline measurements may be off. In our example here, we will assume the frame is aligned and shell is centered. Begin by measuring the diameter of the downtube, and divide this number by 2. In our case, the seat tube is 44mm, so it is 22mm from the right side edge the tube the bike center line.

Next, measure the distance from the downtube edge to the middle of the chainrings. On a two-chainring bike, begin by measuring from the largest ring to the tube. Our bike below measure 29mm from the outer ring to the tube. Next, measure the outside-to-outise of the two chainrings, and divide this by 2. The bike below is 9.8mm outside-to-outside, making it 4.9mm to the middle. Deduct 4.9mm from the 29mm, and it is 24.1mm from the middle of rings to the tube. Add the 22mm for the tube-to-center, and it is 46.1mm from the middle of the crankset rings to the centerline of the bike.

For three chainring bikes, measure from the outer edge of the middle ring to the tube. Next, measure the thickness of the ring at the tooth. In our example, it is 23mm from the middle ring to the tube. Next, measure the thickness of the ring at the teeth. In the example below, a tooth is 2mm wide. Divide the 2mm by 2 to reference the middle of the middle ring. Deduct this 1mm from the 23mm, making it 22mm from the crankset center to the tube. Add this to the 22mm of tube to bike center, and it is 44mm from the middle of the rings to the centerline of the bike.

Chainline from Rear Hub

It is possible to estimate the desired chainline of a bike from the rear cogs. This method assumes the frame is aligned, or that you account for misalignment in the calculations. See Frame Alignment.

Procedure for determining chainline:

1. Measure from the outer most cog face to the face of the locknut. This can be done with the wheel in place, or with the wheel removed. If measuring in place, use feeler gauges or even hex wrenches to measure the distance from the inner face of the right dropout to the face of the smallest cog. These two options are seen in the images below.

   

   

2. Measure the width of the rear cassette or freewheel cogs from outside to outside cog faces. Below is a chart of the common cassette systems.
3. Measure the hub width from locknut to locknut face. It is most accurate to remove wheel and cogs.
4. To determine the rear cogs chainline, use the formula:

   (Hub width÷2) - (Cassette width÷2)- Gap to frame = Chainline of Rear Cogs

What is desired in the formula is the distance from the bike's center plane to the cogset middle. Taking the hub width and dividing by two defines the mid plane or center of the bike. Dividing the cogset width defines the middle of the gears. The gap from the cogset to the frame is then deducted. The resulting number represents the distance from the bike center plane to the middle of the cogset, or chainline.

To help speed the process, find below some typical cogset measurements. It is always best to measure your own set, as these numbers may not represent your cogs exactly.

• Campagnolo® cassette 10 speed: 38.8mm
• Shimano® cassette 10 speed: 37.2mm
• Campagnolo® cassette 9 speed: 38.2mm
• Shimano® cassette 9 speed: 36.3mm
• SRAM® cassette 9 spped: 36.5mm
• Campagnolo®: cassette 8 speed: 36.9mm
• Shimano® cassette 8 speed: 35.4mm
• SRAM® cassette 8 speed: 35.4mm
• Shimano® cassette 7 speed: 31.9mm
• SRAM® freewheel (thread on type) 8 speed: 36.8mm
• SRAM® freewheel (thread on type) 7 speed: 31.8

As an example, assume some hub is 130.6mm wide at the locknuts. The bike is a Shimano® 8 speed. The cogs are about 35.4mm wide. Assume we measure the outer cog to frame and find it is 4.5mm.

The bike center line is in the middle of the hub, so the center line is a 65.3mm from each locknut. The cogset middle is then:

(130.6÷2) - (35.4÷2) - 4.5 = 43.1mm

The rear cog middle is effectively 43.1mm from the bike center line. The front chain rings should be about the same distance from the center line. It is possible, however, to still have acceptable shifting with less than perfect chainline. Manufacturers typically specify a front crankset chain of slightly longer than the rear chainline. In this case, as 45mm chainline would likely work. A 50mm chainline would probably be too long.

Shifting Issues Related to Chainline

If either the front or rear sprockets are either too much inward or outward relative to the other, there may be certain shifting problems. However, if a bike chainline measures off, yet the bike has no problems shifting, the bike should be considered acceptable. No "fixing" of the chainline is then required. The following are typical problems that may be caused by chainline issues.

• Chain jumping off large chainring when front derailleur is correctly adjusted.
• Chain riding off lower derailleur pulley when derailleur or hanger is not bent
• Chain rattling on inner faces of front chainrings.
• Chain derailling off inner chainring when front derailleur correctly adjusted.
• Front derailleur cannot be adjusted to stop over shifts while still allowing good shifting.

On certain bikes, the chain may tend rub and rattle against the front rings while riding in certain gear combinations. This is common on many bike when riding in the so-called "cross-chaining" combination of the smallest front ring, and the smallest rear cog. An example of a gear combination that is likely to rub is shown below.

Generally, the shorter distance from the bottom bracket to the rear hub, the more likely a rattle from gear combinations will occur. There may in fact be several gears that are unuseable on any given bike. It is possible to minimize or eliminate this problem by moving either the front or rear cogs. Even if the bike is has so-called perfect chainline, it may help the riding and shifting to create an "error" to solve shifting existing issues.

FORK STEERING COLUMN LENGTH AND SIZING

Cutting and Sizing Forks

Typical Tools and Supplies:

• Saw Guides SG-1, SG-2, SG-3, SG-6
• Hex wrenches (commonly 5mm and 6mm)
• Hack saw, good quality blade of 24 TPI (32 TPI for carbon)
• Files, flat and round
• Tape measure and caliper
• Bench vise (optional)
• Rags

Service Procedures

This article will discuss cutting and sizing of bicycle forks. See also related articles:

• Threadess-type headsets, see Threadless Headsets.
• Threaded-type headsets, see Threaded Headsets.
• Machining the fork crown see Fork Steering Column Milling.
• Headtube reaming and facing see Headtube Reaming and Facing.
• Headset types and nomenclature see Headset Type
• Installing threadless star-fangled nut see Installing Star Fangled Nut with TNS.

The steering column on new forks typically come longer than required. The column is then cut for the size according the particular bike it is to be installed in. There are two basic methods for determining steering column length. The fastest method is to take appropriate measurements and determine the length mathematically. Another option is to installing the fork without cutting it and then measuring the amount necessary to cut. The fork is then removed, cut, and re-installed. In either case, use care as cutting a steering column too short can be an expensive mistake.

Threadless Type Forks

Threadless type forks have no threads on the outside of the steering column. Headset bearing adjustment is done by pressure from an adjusting cap on top of the fork. The sizing procedure using measurements is described first.

Begin by measuring the length for the head tube and write this number down. Do not include any pressed cups or races.

Next, determine the stack height of the headset to be used. Stack height is basically the amount of steering column length the headset will occupy. A new headset in the box will commonly have the stack height listed on the box. The stack height listed on new headsets does NOT include any extra washers and the stem height. YOU MUST ADD STEM HEIGHT AND ANY EXTRA WASHER TO STACK HEIGHT BEFORE CUTTING.

It is always a good idea to double check the stack height listed by actual measurements. Assemble the lower part of the headset with bearings in place. Measure the from the fork crown race to where the lower pressed race would enter the head tube.

Next, measure the upper stack from where the upper pressed race would enter the head tube to the top of the adjusting race. Add any spacers and add the height of the stem.

Add all these numbers together. You must now deduct a bit to allow a gap between the top of the stem and the top of the steering column. Typically, 3mm is adequate. See image below for adequately sized steering column.

Threadless forks with carbon fiber steering columns have special concerns. There is a limit to the amount of spacers between the stem and the headset. Too many spacers may stress the carbon fiber and lead to failure. Contact the fork manufacturer for limits in regards to your fork. Generally, manufacturers recommend no more than 20mm additional stack height between stem and upper race.

Threadless Sizing Example

1. Our bicycle has a head tube of 103mm.
2. The lower stack measures 12.5mm.
3. The upper stack, including a wide washer, measures 20.5mm.
4. The stem height is 41mm.
5. The total of lower stack, upper stack, washers, and stem is 74mm. That would place the fork exactly at the end of the stem, so we deduct 3mm for a working total of 71mm
6. Add our 71mm to the head tube length of 103mm for a steering column length of 174mm. If you end up with a decimal answer, round up when cutting.

Assembly / Disassembly Technique

If the headset is already installed, an alternate but slower technique to determine steering column length is to assemble the steering column into the head tube with bearings in place, and assemble stem and spacers on top. Scribe fork at top of stem. Remove fork and cut 3mm below scribe line.

Cutting Steering Column- Threadless

It is recommend to use saw guide SG-6 to cut threadless steering columns. This tool holds the fork square to the saw blade. Use of a good quality and sharp hack blade is needed for a properly cut column. Generally, 24 teeth per inch are recommended for steering columns.

NOTE FOR CARBON FIBER: For carbon fiber steering column, a finer 32 TPI blade is recommended. To minimize dust from the carbon, keep the blade wet. If you prefer to use a "diamond rod blade", it is possible to install washers to widen the guide slot of the SG-6. Another option is to use the outer blade as a guide. Hold the diamond blade against the outside steel face of the SG-6. Align the cut mark to this outside face, and press gently against the tool as you cut. Note that this will visually mar the tool. Use a fine emery cloth to finish the end.

1. Determine correct length of steering column. Mark column using marker or scribe.
2. Place fork inside SG-6. Loosely secure handle.
3. Move SG-6 saw guide opening over mark on column.
4. Secure SG-6 handle and place SG-6 in vise.
5. Cut through column. (NOTE: Cut with pressure only in forward direction. Do not apply excessive pressure on blade.)

   

6. Loosen handle and move column to slightly protrude past cover plate.
7. Use flat file to finish end of column. Use round file or de-burring tool to remove sharp inside edge of column.
8. Loose handle and move column further through cover plate. Leave handle loose to allow column to rotate.
9. Rotate fork and use flat file to bevel outer sharp edge of column.
10. Remove fork from SG-6.

Threaded Type Forks

Threaded forks require similar measurements as threadless forks. Begin by measuring head tube length. Next, determine stack height. The stem is not included in figuring stack height at all. If you are measuring stack height, assemble the lower part of the headset with bearings in place. Measure the from the fork crown race to where the lower pressed race would enter the head tube. Next, measure the upper stack from where the upper pressed race would enter the head tube to the top of the adjusting race. Add any spacers, including any brake housing stops or reflector brackets. Measure the height of the locknut, but deduct the amount of any "lip" at the top of the nut. The steering column should not contact this inner lip when the locknut is secured. See cross section below.

Threaded Fork Example

• Our bike has a head tube of 205mm.
• The stack height including washers, and accounting for locknut lip, is 42mm.
• The steering column should be 247mm long.

Cutting Steering Column - Threaded

It is recommend to use saw guide SG-1 (1" column), SG-2 (1-1/8" column), or SG-3 (1-1/4" column) to cut threaded steering columns. This tool holds the fork square to the saw blade. Use of a good quality and sharp hack blade is needed for a properly cut column. Generally, 24 teeth per inch are recommended for steering columns.

1. Determine correct length of steering column.
2. Clamp SG securely into vise.
3. Thread column into Saw Guide SG. Measure from base of fork crown to gap in guide plates. Thread SG as necessary to achieve correct measurement.
4. Cut through column. (NOTE: Cut with pressure only in forward direction. Do not apply excessive pressure on blade.)
5. Thread column until it slightly protrudes past cover plate.
6. Use flat file to finish end of column. Use round file or deburring tool to finish inside edge of column.
7. Thread column further through cover plate.
8. Use flat file to bevel outer thread at about a 45 degree angle. This allow easy start of threaded races and locknut.

   

9. Remove fork from SG

For information on threadless headset installation and adjustment see Threadless Headsets. For information on threaded headset installation and adjustment see Threaded Headsets.

FORK AND FRAME DROPOUT ALIGNMENT Using FFG-1 Dropout Alignment Gauges Typical Tools and Supplies: Repair Stand. FFG-1 Frame and Fork Dropout Alignment Gauges This article will discuss alignment of rear wheel dropouts and fork dropouts. See also related article, Frame Alignment.. For rear derailleur hange alignment, see DAG-1 use. The front and rear wheels fit inside frame axle dropouts. These dropouts should be aligned so the inside faces are parallel to one another and square to the axis of the hub axle. If a dropout is badly misaligned, it may make the wheel difficult to get in and out. Additionally, it will stress the axle when the quick release is closed. The face of the hub locknut will try to align with the dropout face. A bent dropout will cause the axle to flex and in some cases bend and break. Typically, misaligned dropouts will not effect how a wheel centers in a frame, unless the dropout is extremely misaligned. Bent dropouts will stress axle through the hub locknuts. Important Alignment Note: There are some bicycle dropout designs that do not allow correction by bending, or cold-setting. Extremely extrememly thick dropouts typically cannot be bent. Other examples include most suspension forks, most titainium frames, and oversized dropouts for the 14mm "freestyle/bmx" axles. When a dropout is bent for correction, the frame tubing does not bend. Additionaly, the dropout face does not bend. What is being bent is the narrow section between frame and dropout. If there is not a narrow section between the frame and dropout, it may not be repairable. Without this "neck", you are attempting to bend the frame tube. Additionally, dropouts that are bonded into the frame, such as on carbon fiber frames, may not be repairable. Consult with the manufacturer if in doubt. However, even if the bicycle design will not allow correction, it is useful knowledge to inspect dropout alignment. An example of non-repairable bonded dropouts in a carbon fork. Once dropouts are aligned, they tend not require constant re-checking. When the hub is clamped in place, the system is quite strong. Even extreme riding and smashing the wheel is unlikely to bend the dropouts. Procedure for Dropout Alignment Rear dropouts with centering screws: First, install dished wheel in frame, and pull axle to screws. Check that wheel is centered, adjust screws as necessary. For the rear, slide spacer to inside of dropouts. For front, slide wide spacer to outside of dropouts. Pull FFG-1 fully up into dropout. Hold threaded shaft and secure T-handle clockwise firmly against dropout. If tool begins to move, stop securing, tool is tight enough. Adjust bushings until there is a slight gap between them. Move threaded bushings side to side until gap is centered in dropouts. View FFG-1 from all directions for any offset between bushings. Error may also be felt by running a finger across the gap. An example of parallel but offset dropouts. Move left side upward and right side downward. Begin by moving left dropout upward. To correct by bending, grab bushing with one hand, and handle with other. Bend by moving hands opposite directions. If in doubt as to which side to bend, flex gently and note movement of bushing before proceeding to bend. Correct offset until bushing cylinders show no error greater than 0.5mm. View bushings for any gap opening that is not parallel to face of bushing. Correct by bending dropout. Again, if in doubt in choosing one side, flex handle and note movement of bushing. If largest gap is less the 0.5mm, drop outs are adequately aligned. See also related article, Frame Alignment..

FRAME ALIGNMENT

Typical Tools and Supplies:

• Repair Stand. Holds bike for measuring. Use bench vise for actual bending.
• FAG-2 Frame Alignment Gauge
• FFS-1 Frame and Fork Straightener (as necessary for leverage)
• Bench vise and steel bottom bracket cups for shell protection
• Measuring caliper and angle finder

This article will discuss frame alignment and the use of the Frame Alignment Gauge FAG-2. Frame alignment issues and repairs are best addressed by professional mechanics and frame builders. If your frame does not ride quite "right", it is worth having the alignment checked by these professionals.

Frame alignment is also related to wheel dropout alignment. The use of dropout alignment tools FFG-1's is discussed at Dropout Alignment Produceres. Generally, dropout alignment should be inspected after checking the frame. Common frame alignment issues arise from the rear triangle being misaligned relative to the front triangle. Procedures to check front triangle alignment are discussed at the end of this article.

Frame alignment is important to the performance of the bicycle. Frame misalignment may result in the following problems:

• Handling and tracking problems, as a result of the wheels not being aligned to the bike's mid-line.
• Chainline and shifting problems from the rear cogsets being pooorly aligned with the front chainrings.
• Difficulty in removing and installing wheels. This can result in slow wheel changes.

However, it is important to keep in mind that a bike or frame need not be "perfectly" aligned to perform well. All manufacturered components and frames are made to certain tolerances. Frame alignment should be checked in order to address specific issues and symptoms. It is not typically measured and addressed as an issue in its own right. If a bike is not showing alignment symptoms, it probably does not need "fixing".

The Park Tool FAG-2 Frame Alignment Gauge acts much in the same way as a wheel dishing tool. One side of the bike is check for symmetry against the other side. If the rear part of the bike, the rear triangle, is off either left or right, it will show by using the Frame Alignment Gauge. In the image below, the left side is being referenced and then compared to the right. The rear triangle on this bike is off toward the left side of the bike's mid-line.

IMPORTANT NOTE: It is possible to cold-set or re-bend only certain frames when correcting alignment problems. Some frame material is either too rigid or too fragile to bend. When a frame is bent for alignment, you must exceed the "yield" point of the material. This is the point were the material will bend and then stay permanently deformed. In some materials, the point at which it will yield is very close to the point where it will simply fail and break. Thin aluminum tubing, as an example, should generally not be bent. Carbon fiber frames, such as the one seen below, will not take a cold-set. This material tends to simply flex, and then at some point, break. If in doubt, check with the frame manufacturer.

There are often other methods to correct problems and issues arising from a misaligned frame. For example, hub spacers can be added or removed for wheel fit into frame. The wheels may be purposely "misdished" for better centering to the bike's mid-plane. Different bottom bracket spindles will re-posiiton chainrings for better alignment to rear cogs.

FAG-2 Alignment Procedures

Begin frame alignment by measuring the width of the hub over the locknuts. Measure from locknut face to locknut face, where the nuts would contact the frame dropouts. Write this number down for reference.

Measure inside the width of frame dropouts and compare this to hub. If the frame is too wide or too narrow as compared to the hub, it may be awkward removing and installing the wheel. Generally, the frame and hub should width within 1-2mm.

Also note the left and right dropout thickness. If either side is different, record the difference and account for this difference when measuring the frame. For example, the replaceable hanger seen below makes the right dropout effectively 2mm thicker than the left side. When this example frame is centered, the FAG-2 will show a 2mm gap between the pointer and left side dropout.

Place the long straight portion of the FAG-2 along side the left side of the head tube and the seat tube. Make certain the gauge rests on the tubes themselves, not head lugs, welds, bottle cages, etc. Slide the adjustable pointer as necessary to adjust for variations in chain stay length. Turn the pointer knob until the pointer contacts the dropout face.

NOTE: Large down tubes on small frames may make it difficult to contact head tube. In these cases it is possible to extend the width of the head tube by holding a shim, such as a hex key wrench, held flat against head tube. This allows an accurate measurement from the head tube. Additionally, some bikes have no seat tube. In these cases, it may be possible to lower the seat post and use the seat post as a representation of seat tube.

After referencing the left side of the bike, compare this setting to the right side. Set the FAG-2 to contact the same three points on right side, mirroring the tool placement at the head tube, seat tube, and rear dropout. There are three possible results of this comparison:

• Result #1: Rear droputs are centered. There is the same three point contact as on the right side as the left side.
  • This rear triangle would be centered to the head tube and seat tube. If dropouts are wide or narrow compared to hub, bend each stay out or in only one half of the amount of the error. Double check centering again with FAG-2 after bending both stays.
• Result #2: Dropouts are off to left of mid-plane. There is a gap between right dropout and pointer on FAG-2.
• This rear triangle is off centered to the left of the mid-line. The amount of centering error is one half of gap size. For example, a 1mm gap means a wheel is off only 0.5mm to the bike's mid-plane. If the frame is too narrow compared to the hub, bend right dropout outward. If frame is too wide compared to hub, bend left dropout inward. If frame is the same width as hub, bend both sides toward the right a slight amount, rechecking both sides with FAG-2.



Result #3 Dropouts are off to right of mid-plane: There is a gap between seat tube and FAG-2 gauge when pointer contacts headtube and right dropout.



In this case, if FAG-2 is made to rest on seat tube, pointer will sit inside face of dropout.



The rear stays in Result #3 are off toward the right side of the mid-line. In this situation, reset the FAG-2 to referece three-point contact at head tube, seat tube, and dropout on the bike's right side. Move FAG-2 to check the left side of frame. A gap will now be seen between the pointer and left dropout. Seeing the error at the dropoutthe dropout rather than the frame.

To cold set the frame, it is best to hold bike securely by the bottom bracket. A simple method to do this is to remove the bottom bracket, and install steel adjustable-type bottom bracket cups. Both cups should extend past shell. Mount bottom bracket in the hard jaws of a large vise. The cups will protect the frame.



When bending the dropout and stays, it is best to begin with mild hand pressure. Check progress by re-checking frame width with a caliper and centering with the FAG-2. Increase pressure as necessary.



If necessary, use FFS-2 Frame and Fork Straightener. This tool provides a lot of leverage, so use with caution.

When bending a frame, bend one stay at a time as necessary. Always consider hub width and frame width when aligning rear triangle. Use the FAG-2 and a caliper together to help minimize the amount of bending necessary. It is common for the one stay to move slightly when the other stay is pulled. This is because the stays are joined with a bridge near the bottom bracket and on the seat stay. Centering tolerance for FAG-2 pointer-to-dropout gap is generally considered 1-2mm. Adequate tolerance for frame width-to-hub difference is also generally considered 1-2mm. However, bikes can certainly perform adequately with even greater error than these numbers. Check with the frame manufacturer for specific tolerances.




Main Frame

The head tube, top tube, down tube and seat tube comprise the "main frame", or front triangle. Significnat alignment issues are uncommon from this part of the bike. If this part of the frame has become bent, repair is especially difficult, and is not generally recommended.

The axis of the head tube should be parallel to the axis of the seat tube. One method to determine this is a frame table, typically used by frame builders. This is a "surface plate", on which the bike frame is mounted. A series of measurements are taken to determine alignment. It is the most accurate method for checking alignment.



An alternative and practical method uses an angle finder. Simply mount the bike in a repair stand, or even lean bike against a wall. Measure and note the head tube angle. Compare this to the seat tube angle. If the two are within a degree, the bike should be adequately aligned. For example, if the head tube reads 89-degrees, the seat tube should read between 88 and 90-degrees.





Repair of a misaligned front end is difficult, and is likely to involve extensive force and possibly more damage. It is generally not recommended. Typically, a large mandrel is placed in the head tube. The bottom bracket is held secure in a vise. The head tube is twisted in a direction to counter the alignment problem. This repair is rarely sucessful, and the bending places a torsional or twisting load on the top tube and down tube, especially at the joints. Inspect this bike often for failure of joints.


Frame Failure

The bicycle frame tubing and joints may in some cases fail or break. In some cases, a joint may be poorly made, or the design may simply too weak for the use. Failure may also be the result of a crash, causing the tubing joints to yield and begin failing. The repeated stress of riding results in a "stress cycle", which may cause cracks and eventually failure. It is also possible that an attempt to repair a bike by re-bending tubing causes failure.

Repair of severely bent tubing from a crash is often impossible or very impracticle by re-bending. In welded frames, tubing can sometimes be replaced. If the frame is aluminum, it will often require heat treatment after repair to restore strength lost from the welding of the tubing. Bonded frame repair is best left to the manufacturer.

Bicycle frames are best inspected during cleaning. Most types of paint tend to be somewhat brittle and will crack if the material has moved under it. The left image below shows a crack at the bottom bracket shell. The first indication was paint showing the failure. An inspection inside confirmed the crack. The second image is a crack in the left chain stay.





Composite frames are also susceptible to failure. In the frame below, a metal bottom bracket sleeve was bonded into the frame. This sleeve has loosened from the frame and is creaking.



The downtube of the frame seen below shows signs of a front impact. The tube has a wrinkle under the lower side. The properties of the metal in this damaged area have changed. This tube will likely crack at this point and eventaully fail. The damage in this bike is not repairable other than by tube replacement.



The stress of flexing fork legs is transmitted to the fork crown. This crown has cracked at the narrow material above the brake caliper mounting hole. Fork failure is especially dangerous.

HANDLEBAR GRIP INSTALLATION

TYPICAL TOOLS AND SUPPLIES

• Repair Stand, holds bike secure for easy work.
• HBH-1Handle Bar Holder (makes work easier)
• Scissors and sharp knife or razor blade
• Contact cement (optional)
• Alcohol (substitute window cleaner or hair spray) for MBT grips

This article will discuss the installation of grips on flat handlebars. For drop style handlebar tape installtion, see Handlebar Wrapping below.

The handle bar grips of the upright or flat bar should not slip or move during the ride. With much use and time, grips tend to expand and will loosen on the bar. It is possible to help the grip bond to the bar using adhesive glue and or wire tying. However, grips will eventually wear out and should be replaced. Some models of grips a designed with a locking collar system, making the grips secure until they are completely worn out.

Bar grips are typically made from a rubber compound. Gluing rubber to a metal bar is a difficult bond for most adhesives. Contact cement and tubular tire cements are good choices for glue. For new grips, glue is typically not required. Make sure the levers and positioned to allow the grips to slide fully onto the bar. If you are using glue, use a thin layer inside the grip rather than on the bar. It can help to lubricate the inside of the grip with non-oily liquids, such as rubbing alcohol, hair spray, or window cleaner. Do not use oil of any type, as this will prevent any gripping on the bar.

Grip Removal

If the old grips are worn out and are being replaced, they may be cut off the bar. It is also possible to remove and re-use the grips if they are in adequate condition. Use a long flat tipped screwdriver worked gently under the inside edge of the grip. Drip or spray liquid such as window cleaner, hair spray, or rubbing alcohol in the gap. Work the solvent around the grip to loosen the bond, and slide the grip off the bar.

If the grip had a sealed end, it is also possible to remove it with compressed air. Use blow tip and place inside end of grip. Wiggle grip while pulling as blown air loosens grip from bar. It may be necessary to have someone help plug the opposite bar end to remove second grip.

Wire Tying Grips

It can help in some situations to wire tie the grips to the bar. Good quality stainless steel wire of 26 gauge or 24 gauge is wrapped tightly around the inside and outside edges of the grips. Wrap one or two wraps around the both outer edges of the grips. Special pliers called "safety wire pliers" help wrap the wire tightly.

Locking pliers can also be used for a good wrap. Secure the pliers about one-inch (25mm) from the grip. Pull on the pliers as you rotate. When the wire begins to dig into the grip, the wire is tight enough.

Cut the wire about 3/8-inch (10mm) from the grip. Use needle nose pliers to bend the end of the wire into a hook. Jab the cut end into the grip toward the outside of the wire wrap. Check the at the cut end is safely buried in the rubber grip.

MTB POSITIONING CHART

This article will describe the use of the MTB Positioning Chart for competitive road bicycles. A similar article for road bikes is at Road Bike Positioning. The chart is intended for use primarily by the mechanic, although it can be used by the cyclist. It is often useful to quantify and record the various aspects of a cyclist positioning adjustments. It can also be useful for a cyclist to track and record changes to his/her position. For example, if saddle height is raised, the new height and date of change can be noted. This will allow the cyclist to track changes in performance. Additionally, if the bicycle is lost or somehow ruined, and a new bike must be quickly built, this chart will help in setting up the new bike to closely match the original positioning.

The MTB Positioning Chart can be downloaded as an Adobe® PDF file. The Adobe® Reader program is required to view and print this file. See the Adobe® web site if you do not have this program.

Procedure

Tools to aid in completion of this chart are a metric tape measure, angle protractor, plumb bob, and straight edge. Begin with the bicycle on level ground. If possible mount bike on trainer and level bike by checking that both wheel axles are the same distance from the ground.

There is often more than one method for measuring a component or position. It is important that the user be consistent and that the method of measuring is noted. Record all units of measurement. For example, record "50cm" for fifty centimeters, and "50mm" for fifty millimeters. Record and note with the assumption that someone else will need to set up a bike from only this chart.

Begin by recording customer/rider information, such as name, address, etc. Also record bike make, model, year of production, and serial number. Also record bike's color scheme and any unique or obvious physical characteristics that might distinguish this bike. Assume this will be used in a police report of a stolen bike. It is also recommended that the traveling rider carry a recent photo of the bicycle.

A: Saddle Height
Record saddle height and note method of measurement. A simple method is to place a straight edge on top of the saddle and record height from either bottom bracket center or the pedal spindle center to the lower edge of straight edge. Measure along the seat tube.

B: Saddle Height Over Bars
Record bar-to-saddle height difference. A simple method is to measure perpendicularly from saddle to ground, and then bar to ground, and take the difference between these two measurements. Measure from top edge of grip, and from straight edge on top of saddle.
    

C: Saddle to Handlebar Reach
Measure from saddle tip to the center of the bars at the stem. This gives a reference for bar reach.

D: Saddle Angle or Tilt
Using a straight edge on top of saddle, measure saddle angle from horizontal. Circle either "upward" or "downward" sloping angle on chart as appropriate.

E: Saddle fore-aft
Drop a plum bob line from the saddle tip and measure distance from line to center of bottom bracket. It is easiest to tape line to saddle so it hangs from saddle end and extends freely toward the ground.

F: Saddle Brand and model
Record saddle brand and model.

G: Stem Length
Measure center of the stem binder bolt to the center of the bars. On a front-plate type stem, this is usually to the gap at the plate.

H: Stem Angle
Record the stem angle from horizontal. Especially on shorter stems, hold level finder so it is parallel to stem angle.



NOTE: Some stem manufacturers specify stem angle using the steering column as a reference. If this angle is known, record this as well. It is possible to measure the manufacturers angle by taking the stem angle and the quill (steering column) angle. Stem angles sloping upward are recorded as positive numbers, while stem angles sloping downward should be recorded as negative numbers. For example, a bike is measured and the angle from vertical is 18-degrees. (This means the headtube angle as the bike sits is 72-degrees.) The angle from horizontal is 25-degrees. The manufacturer's angle is then 90 - 18 + 25 = 97 degrees. In the right image below, assume the stem sloped downward 6 degrees instead. The manufacturer's angle is then 90 - 18 + (-6), or 66 degrees.

       Manufacturer's angle = 90 - Angle from Vertical + Angle from Horizontal

I: Handlebar brand and model
Some riders prefer a particular brand and shape of bar.

J: Handlebar Width
Measure bars from end to end.

K: Handlebar Tilt
Flat bars are typically made with a slight bend. This can be difficult to measure, especially with grips on the bike. In the example images below, the left image may be recorded as "slightly up". The center image would be "level" and the right image would be "slightly down".

L: Handlebar Extensions
Measure angle of bar ends from horizontal.

M: Brake Level Angle
Measure angle of brake levers from horizontal. The lever body of various manufacturers may not allow direct measurement of lever action. Hold protractor parallel to movement of lever.

N: Brake Lever Reach
If brake levers are not set at full extension, record lever distance from bars. Record from grip to inside edge of lever at closest point.

O: Crank Length
Record crank length. Cranks are measured from the center of the pedal mount to the center of the spindle square. Arm length in millimeters is typically labeled on the back of arm.

P: Pedal
Record the pedal make and model. Changing pedal types may affect the saddle height.

Q: Shoes
Record shoe size, make, and model. It is also useful to record user preference of either a fixed or floating type of cleat. The cleat position on the sole may also be recorded.

Rotation: Engage shoes on pedals, without rider. Hold shoe parallel to crank. Measure distance from crank bolt to center of shoe sole. If the pedal has adjustable float, hold sole in middle of float range. If cleat has float, hold sole toward crank.


Fore-Aft: Record cleat fore-aft position on sole by measuring from tip of sole to cleat.

ROAD POSTIONING CHART

This article will describe the use of the Road Positioning Chart for competitive road bicycles. A similar article for MTB bikes is at MTB Bike Positioning. The chart is intended primarily for the mechanic to quantify and record the various aspects of a cyclist positioning adjustments. It can also be useful for a cyclist to track and record changes to his/her position. For example, if saddle height is raised, the new height and date of change can be noted. This will allow the cyclist to track changes in performance. Additionally, if the bicycle is lost or somehow destroyed, this chart will help in quickly setting up the new bike to closely match the original positioning.

The Road Positioning Chart can be downloaded as an Adobe® PDF file. The Adobe® Reader program is required to view and print this file. See Adobe® if you do not have this program.

Procedure

Useful tools for measuring rider position:

• Positioning Chart, plus pen or pencil
• Metric tape measure
• Angle finder
• Plumb bob
• Straight edge
• Measureing caliper

Begin with the bicycle on level ground. If possible mount bike on trainer and level bike by checking that both wheel axles are the same distance from the ground.

There is often more than one method for measuring a component or position. It is important that the user be consistent and that the method of measuring is noted. Record all units of measurement. For example, record "50cm" for fifty centimeters, and "50mm" for fifty millimeters. Complete the chart and makes notes with the assumption that someone else will need to set up a bike from only this chart.

Begin by recording customer/rider information, such as name, address, etc. Also record bike make, model, year of production, and serial number. Also record bike's color scheme and any unique or obvious physical characteristics that might distinguish this bike. Assume this will be used in a police report of a stolen bike. It is also recommended that the traveling rider carry a recent photo of the bicycle.

A: Saddle Height

Record saddle height and note method of measurement. A simple method is to place a straight edge on top of the saddle and record height from the bottom bracket center to the lower edge of straight edge. Measure along the seat tube.

B: Saddle Height Over Bars

Record handlebar-over-saddle height difference. A simple method is to measure perpendicularly from saddle to ground, and then bar to ground, and take the difference between these two measurements. Use a straight edge on top of the bars, and measure to lower edge of the straight edge.

     

Another option is to use a long straight edge and the level finder. Use level finder to hold straight edge horizontal from saddle. Measure from lower edge of straight edge to top of handlebars.

A related option is to measure from the front axle to the top of the bars. This is a useful measurement when tracking changes in position on the same bike. However, this number is also related to stem length, fork rake and wheel base, making it less useful when setting up a duplicate position on a different frame.

C: Saddle to Handlebar Reach
Measure from saddle tip to the center of the bars at the stem. This gives a reference for bar reach.

D: Saddle Angle or Tilt

Using a straight edge on top of saddle, measure saddle angle from horizontal. If the front end of the saddle is raised, record this upward sloping saddles as a positive number (+). Record downward sloping saddles with a negative number (-).

E: Saddle fore-aft
Drop a plum bob line from the saddle tip and measure distance from line to center of bottom bracket. It is easiest to tape line to saddle so it hangs from saddle end and extends freely toward the ground.

F: Saddle Brand and model
Record saddle brand and model.

G: Stem Length

Measure center of the stem binder bolt to the center of the bars.

H: Stem Angle
Record the stem angle from horizontal. Especially on shorter stems, hold angle finder so it is parallel to stem angle. In the stem is downward sloping, record as a negative number ( - ). It stem is upward sloping, record as a positive number ( + ).

NOTE: Some stem manufacturers specify stem angle using the steering column as a reference. If this angle is known, record this as well. It is possible to measure the manufacturers angle by taking the stem angle and the quill (steering column) angle. Stem angles sloping upward are recorded as positive numbers, while stem angles sloping downward should be recorded as negative numbers. For example, a bike is measured and the angle from vertical is 18-degrees. (This means the headtube angle as the bike sits is 72-degrees.) The angle from horizontal is 25-degrees. The manufacturer's angle is then 90 - 18 + 25 = 97 degrees. In the right image below, assume the stem sloped downward 6 degrees instead. The manufacturer's angle is then 90 - 18 + (-6), or 66 degrees.

Manufacturer's angle = 90 - Angle from Vertical + Angle from Horizontal

I: Handlebar brand and model

Handlebars vary in shape and design. Record the brand and model.

J: Handlebar Width

Measure width from center to center at the lower section of the drops. Some manufacturers specify width as an outside to outside dimension. However, when a bar is wrapped with thick tape, this makes an accurate measurement more difficult. Record method of measurement. For example, "46cm center-to-center". It is use to know bar width when bike is crashed. The width after the crash can be compared to the width before the crash. Replace bar if this measurement is different.

K: Handlebar Tilt or angle

Measure drop type bar angle off of lower section of drops using level angle finder. Record any positive or negative angles to be consistent with the system use on the stem. In other words, if the lower section is pointing downward, or more toward the rear axle, record this as a positive number. If the lower section is sloping upward, toward the rider, record this as a negative number.

L: Handlebar Clip-on Bars or Aero Bars

Measure angle of aero-type extensions from horizontal. If the bar extension is adjustable in reach, also record reach from bar center to end of extension.

M: Brake Level Position
Record position of brake levers on handlebars. Place straight edge on lower drops and measure tip of lever as above (+) or below (-) this line.

N: Crank Length

Record crank length. Cranks are measured from the center of the pedal mount to the center of the spindle square. Arm length in millimeters is typically labeled on the back of the crank.

O: Chainring Sizes

Record the preferred large and small chainring sizes.

P: Pedals

Record the pedal make and model. Changing pedal types may affect the saddle height.

Q: Shoes

Record shoe size, make, and model. It is also useful to record user preference of either a fixed or floating type of cleat. The cleat position on the sole may also be recorded.

Rotation: Engage shoes on pedals, without rider. Hold shoe parallel to crank. Measure distance from crank bolt to center of shoe sole. If the pedal has adjustable float, hold sole in middle of float range. If cleat has float, hold sole toward crank.

Fore-Aft: Record cleat fore-aft position on sole by measuring from tip of sole to cleat.

HANDLEBAR TAPE INSTALLATION (DROP BAR)

TYPICAL TOOLS AND SUPPLIES

• Repair Stand, holds bike secure for easy work.
• HBH-1Handle Bar Holder (makes work easier)
• Scissors and sharp knife or razor blade
• Strapping tape (for drop bars)
• PVC colored tape for ending wrap (for drop bars)
• In some cases, contact cement (MTB grips)
• Alcohol (substitute window cleaner or hair spray) for MBT grips

This article will address wrapping drop style handlebars. For installation of grips on flat handlebars see Grip Installation on Flat Bars.

Handlebar wrapping is a skill that takes practice and patience. See also advanced tips below if you are experienced. Begin by washing your hands, or wear mechanics gloves such as Park Tool MG-1. The finished job should look clean for the user. Make sure any housing that is to be under the bar tape is secure. Use strapping tape to hold housing in place.

Start the roll at the bottom of the bar. Begin so the tape extends well past the bar end. This extra tape is then stuffed into the bar and the bar plug inserted after the wrapping is completed. The direction of the wrap may also effect how it retains it tightness on the bar. Generally, it is the habit of cyclist to pull back on their hands when riding on the top section of the bars. By noting this, you can wrap so this habit will be self-tightening on the tape. Looking from the rider's point of view (from the back of the bike) wrap each side the tape rotates inward from the top. In other words, wrap the right bar counter-clockwise and the left bar clockwise. Note the image below.

If the tape has an adhesive backing, overlap so the adhesive is on the bar.

Handlebar tape will vary in strength between manufacturers. If you are unfamiliar with the brand, assume it is fragile. It helps maintain a tight bar wrap by pulling the tape as you wrap, but too much force in pulling may break the tape. You often need to work the tape by pulling and backing up until it lies down nicely on the bar, especially at the corners. Inspect as you wrap. Notice the image below shows some sloppy taping under the curve.

The tape must pass past the brake levers. There are different methods for wrapping at the levers. Some riders like the tape to cover the bar completely, even at the brake lever. There is often a small piece included with the tape used for the brake lever. Pull the brake housing cover away from the bar and place the tape over the back of the lever. Continue to wrap up and around the small piece and the lever, plus one or two addition wraps past the lever. Fold the hoods back and inspect the tape. An older method useful with very thin tape was to make a "figure-8", wrapping around the lever then back down and around again. This method makes a very bulky area and is not needed or recommended with the commonly available thick tape.

An alternate method used at the lever is simply to wrap past it without the extra tape. This method is common among race mechanics. The extra piece of tape does not add to comfort and is not necessary for a functional wrap.

The amount of bar tape given in a roll varies between tape manufacturers. Generally assume the roll will be short, and wrap the low section with less overlap. Increase the overlap on the upper section where most of the riding takes place. Ending the tape cleaning is possible by marking where you want it to end. Continue the angle of wrap and continue past the ending point. In the image below, the tape should end at the sleeve.

Use a sharp knife or razor blade and make a cut in the tape along the ending line.

Back tape off two wraps and use scissors to extend the cut all the way through the tape. Maintain the line shown by the cut and cut tape cleanly.

Wrap the tape again the cut the tape so the end is at the bottom of the handlebar.

Use your piece of PVC or electrician's tape to end the wrap. Wrap the tape neatly, use care to maintain clean narrow wrap. Again cut so it will end at the bottom of the bar.

Advanced Tips

There are several possible different methods to wrapping. It is often necessary to practice different techniques and see what works best for you and your customer.

A useful technique is to use either a double-sided sticky tape, or to turn the electricians tape upside down for the lower 5-8cm of the bars. This is the area where bars tend to become damage from falls and abrasion. Hold the tape as you make one wrap, then the tape will hold itself. This sticky tape will now help hold the bar tape should it become torn.

An alternative to overlapping the tape at the end of the bar is to first install the bar plug. Next, cut a taper at the end of tape. This allows the tape a smooth and even beginning, rather than a lump from the extra tape.

When riding on the drop section of the bars, it is the tendency to rotate the hands outward. It is possible to reverse wrap direction from start to finish in order to match this tendency. Note the image below has the tape beginning opposite of the taping first described. Wrap each side so the tape rotates outward from the top. In other words, wrap the right bar clockwise and the left bar counter-clockwise.

If you wrap as the image above, you must then reverse the direction of the wrap at the brake levers. Do not cross the back of lever from outside to inside, as is commonly done. Stay on the inside of the lever and continue to the above the lever. See image below. Notice the optional piece of brake lever bar tape is in place. The tape will now be in a self-tightening direction on the top and the bottom of the bars.

Even a well-trimmed end can show underneath the finish tape. If you are using black tape, it is possible to color the edge of the bar tape. After the tape is trimmed for the finish, use a permanent marker to color the inside edge of the tape. It will appear black, the same color as the holding tape.

After finishing the tape, use either a soldering iron or a heated metal tip to sear and seal the tape. This helps prevent the electrician's tape from loosening.

If the finish tape is black, and the tape has a non-black finish, it is possible to color the inside edge. After trimming the end, use a permanent to mark the edge. After the finish tape is applied, it will give a cleaner appearance.

Add some thin tape for color contrast. Make "pin striping" by cutting a roll of tape with a sharp knife or razor blade. Lay the roll of tape on a flat surface. Firmly press the blade into the roll, and rotate the roll. Use care whenever using a sharp edge. Peel the tape up and apply to the finish tape.

HEADSET STANDARDS Bicycle Headset Standards and Nomenclature This article will discuss the various headset types and standards found on modern bikes. The headset of a bicycle allows the fork steering column and front wheel to rotate and turn. There are now several different systems in use on bicycles. The installation and service aspect vary according to the style. This article will review the following headset types: Threaded Threadless Low Profile (Zero-Stack) Integrated System (IS)-angular contact without cups Microtech® Perdido® Columbus®-type (Integrated- angular contact) Campagnolo® Hiddenset(Integrated- angular contact) One-Point-Five Standard (oversized steering column) There are also several bicycle manufacturers using proprietary headsets of unique design. Adjustment procedures will not be discussed here directly. See also related articles: Threadless-type headsets, see Threadless Headsets. Threaded-type headsets, see Threaded Headsets. Cutting a fork to size, see Fork Sizing. Machining the fork crown see Fork Steering Column Milling. Headtube reaming and facing see Headtube Reaming and Facing. Headset types and nomenclature see Headset Type Installing threadless star-fangled nut see Installing Star Fangled Nut with TNS. Conventional Threaded Headsets The threaded headset was once the common headset design for most bicycles. The "threaded" in the name refers to the external threading at the top of the fork steering column. Bearing cups are pressed into the bike head tube. The bearings, which may be loose ball bearings, retainer ball bearings, or cartridge bearings, sit above and below the pressed races. The top most bearing-race has internal threading, and is held in place by a threaded locknut. The stem has no effect on the headset adjustment. Threaded headset sizes are designated by the outer diameter of the steering column. This can seem confusing, because the head cups do not measure the named standard. The threaded standards are 1 inch, 1-1/8 inch, and 1-1/4 inch headsets. The various standards are generally not interchangeable. For more on threaded headset including the various standards see Threaded Headsets. Conventional Threadless Headsets Threadless headsets have many of the same features as Threaded Headsets. Bearing cups are pressed into the bike headtube. The bearings, which may be loose ball bearings, retainer ball bearings, or cartridge bearings, sit above and below the pressed races. The steering column has no threading. The top race uses an internal centering sleeve on the column to maintain alignment to the bearing cup. Pressure is applied to the top race from the stem. Threadless Headsets must use a compatible stem that matches the steering column diameter. The stem binds to the outside of the column, and holds the top race in adjustment. The threadless standards are 1-inch and 1-1/8 inch diameter steering column. For more on conventional threadless headset including the various standards see Threadless Headsets. "Low Profile", "Zero Stack", "Intergrated with Cups", "Internal Headset", "Semi-Intergrated" types This type of headset system has, unfortunately, several names. Cane Creek® uses ZS or Zero Stack, while FSA® uses the Orbit Z series. The low-profile, zero-stack, integrated-with-cups, semi-intergrated, or internal-headset systems use pressed frame cups that act as a holder for the bearings. The cups have a flange, or lip, and sit adjacent to the outer edge of the top and bottom of the headtube. The headtube is a relatively large outside diameter, approximately 50mm, and cups allow the bearings to sit flush or even inside the headtube. The headset bearings sit "internally" to the top and bottom of the headtube. Some models use a cup that holds a cartridge bearing. The cartridge bearing is a slip fit into the cups. The cups act as a bearing holder and do not take bearing movement or wear directly. Other types have the cartridge bearing and cup/holder as a unit. These are simply replaced as a unit when it is worn out. Still another version of this type uses a cup and cone system with caged ball bearings, similar to the conventional threadless headsets. Additionally, the depth of insertion into the headtube will vary between brands and type. If the bike was designed for a shallow cup, a deeper cup will not properly fit. This lack of consensus in depth makes reaming the inside of the headtube problematic. The Low Profile type of headset is adjusted in a similar fashion as threadless headsets. Pressure is applied from an adjusting cap and bolt in the stem. The Low Profile headsets, even the "zero stack", do have some stack height, in spite of their name. The steering column is commonly 1-1/8 inch diameter. Park Tool offers the 690-XL facer for some of the Low Profile headtubes. This facer is used with the 768 Pilot to machine the top and bottom surfaces of the headtube. Below is an image of a Low Profile headset using a cup and bearing as one unit. These systems align bearings to the top and bottom on the headtube faces, there is no angular contact inside the headtube. Note image below with cup pressing into frame. Lip of bearing cup presses against headtube face. Below is an image of the system using bearing cups, cone, and caged ball bearings, similar to conventional threadless headsets. Generally, these are considered less expensive headsets. Integrated- Angular Contact System (without cups) The integrated system uses cartridge bearings that are supported by machining in a specially shaped head tube. The frame may also use pressed rings or retainers inside the headtube. A cartridge bearing slips into these "cups" or supports, and is simply lifted out for replacement. There is no contact with the headtube face. The bearing sits inside the headtube, and references the angular contact. There are different standards within this integrated-angular contact family, and these are not interchangeable. A table at the end of this article summarizes the various standards. The "IS" system is considered the most common. The name Integrated System is not a registered trade name. The system uses the 45-degree bearing contact in the frame. The bearings for the 1-1/8 inch steering columns use a 41mm outside diameter with a 45-degree bearing contact in the frame. The bearing may be marked "36-45". The first number refers to the inside bearing contact with the headset race or centering cone. The second number refers to the frame contact. The less common 36-degree angular contact standard uses a bearing for the 1-1/8 inch steering columns with a 41.5mm outside diameter. The bearings may be marked "36-36". Bearing adjustment in these systems similar to the threadless headset. Pressure is applied from an adjusting cap and bolt in the stem. The image below shows the inside of the specially designed and machined headtube. The inside bevel acts as the bearing "cup". Cartridge bearing are used which drop directly into the headtube as a slip fit. There is no pressing involved. All integrated system headset bearings use the internal bearing support inside the frame, not the top face of the headtube, for proper alignment reference. Internal shoulder "cup" for cartridge bearing of the 45-degree and 36-degree angular contact frames. Use the Park Tool 756-S cutters for the 45-degree angular contact IS frames. See also headtube machining at IS reaming/facing service. The frame below uses pressed inserts or rings for the angular contact. Notice the split in the ring. These press in with only hand pressure against the machined relief in the frame. Campagnolo® Hiddenset The Campagnolo® Hiddenset is a proprietary design, and is basically an integrated-angular contact type without cups. The frame must be compatible with this design for this headset to be used. The bearings cone races do not press into the frame. The frame has a specially machined headtube to accept the bearings. However, this standard is not interchangeable with the Integrated System described above. Adjustment is similar to a conventional threadless headset. Steering columns may be either 1-inch or 1-1/8 inch in this standard. The bearings are a slip fit into the frame. The common 1-1/8 inch standard has a bearing outside diameter of nominally 41.8mm with a 45-degree bearing seat. Campagnolo® brand bearings use a caged ball bearing inside the bearing unit. The unit can be pulled apart to be cleaned and regreased. Some other brands use a non-serviceable bearing, which are simply replaced, not serviced. Microtech® The Mircrotech® headset system is a proprietary integrated system. The frame headtube is machined specifically for the bearing. There is no angular contact in the frame for the bearing, but rather a square edge is recessed below the top and bottom face. The bearings are a press fit inside the frame and sit on the machined edge. Bearing alignment then references the internal machining, not the top and bottom faces. The lower bearing is also a press fit onto the steering column. The 1-1/8-inch forks use a bearing with an outside diameter of 42mm. Bearing adjustment is the same as threadless systems. Perdido® The Perdido® headset is a type of low-profile system, but uses different tolerances. The Perdido® system uses pressed cups into the frame headtube. The bearings are fitted into the cups, and are not a simple slip fit like some of the low profile systems. The Perdido® standard requires a very specific headtube inside diameter. The outside diameter of the Perdido® pressed race is 44.5mm, and the recommended inside diameter of the head tube is 44.4mm. The low profile pressed cups use a 44mm OD. This means a bike designed for Low Profile (zero stack) is not directly compatible with the Perdido® system without first reaming. A bicycle made for the Perdido® can only use Perdido®, it cannot use the Low Profile types. The Perdido® headset is adjusted like threadless headsets. Perdido® is a registered trade name of the Chris King® Company. Columbus® Type Headset The Columbus type headset uses a cartridge bearing holding-cup that is pressed into the frame. The frame has no special seat machined inside the headtube. The frame head tube has an outside diameter of 45mm and a machined inside diameter of approximately 39.9mm. A cup of 45mm outside diameter is pressed into the frame. The cartridge bearings sit above and below the frame in these cups. The bearings are nominally 41.5mm outside diameter and are a slip-fit into the cups. The bearing seat of the cups is 36 degrees. This headset allows the "image" of an integrated system by matching the headtube diameter with the cup outside diameter. The Columbus®-type headsets are not interchangeable with other types. Cups are typically painted with the frame, which assists to hide their appearance on the bike. Adjustment is similar to threadless headsets. Columbus® offers this system to frame builders with steel headtube inserts. These inserts are welded into the frame and are then effectively similar to the integrated system described above. The insert system is also in the 36-degree angular frame contact. The Onepointfive Standard® uses a 1.5-inch diameter (38.1mm) steering column. The headtube inside diameter is approximately 49.6mm. The headsets are conventional threadless types, and but are simply quite large. The adjustment procedure is the same as threadless headsets. Below is a frame cup from the Onepointfive standard next to a 1-1/8-inch standard frame cup. The Park Tool Facer/Reamer 758 is made for this standard. To press the Onepointfive standard cups use the HHP-2 headset press. For more on the Onepointfive see www.onepointfivestandard.com Headset Standards Summary The various headset standards are outlined in the table below. An "interference fit" is also called a "press fit", where the headtube is smaller than the cup/bearing. The cup is pressed into the headtube with force. A "slip fit" allows the bearing to be installed and removed by hand, with no pressing required. In a slip fit, the outside diameter (OD) of the bearing is smaller than the inside diameter (ID) of the frame. Frame Headtube ID Bearing or Press ID Interference of Slip Fit Description 29.8mm to 29.9mm 30.0mm Interference fit Conventional JIS standard for 1-inch steering column, threaded and threadless 30.0mm to 30.1mm 30.2mm Interference fit Conventional "Euro" standard for 1-inch steering column, conventional threaded and threadless Interference fit 33.8mm to 33.9mm 34.0mm Interference fit Conventional 1-1/8 inch for threadless and threaded Interference fit 36.8mm to 36.9mm 37mm Interference fit Conventional 1-1/4 inch for threaded and threadless 38.55mm to 38.6mm 38.5mm Slip fit Integrated-angular contact 1-inch steering column 36 x 36 degree contact 41.05 to 41.1mm 41mm Slip fit Integrated-angular contact 1-1/8 inch steering column 36 x 45 degree contact "IS" or "Cane Creek® types 41.3mm 41.4mm Interference fit Low Profile 1-1/8" steering column, with headtube outside diameter nominally 47mm Frame has no angular contact. 41.55 to 41.6mm 41.5mm Slip fit Integrated-angular contact 36 x36 degree contact TH Industries® ED-36 type 41.85 to 41.9mm 41.8mm Slip fit Integrated-angluar contact 45 x 45 degree contact Campagnolo® Hiddenset standard 41.9 to 42mm 42mm Interference fit Microtech® Integrated- non-angular contact Frame has no angular contact. 43.9mm 44mm Interference fit Low Profile for 1-1/8 inch steering column Cartridge bearing types use slip fit into pressed cup. 44.05mm to 44.1mm 44mm Slip fit Integrated-angular contact 1-1/8" steering column 36 x 36 degree contact 49.6mm 49.7mm Interference fit Onepointfive® Standard Oversized threadless type

THREADLESS HEADSET SERVICE

Threadless-type Headset Removal, Installation and Adjustment

Typical Tools and Supplies Needed:

• Hex Wrenches, for stem removal: AWS series.
• Race Remover, RT-1.
• Headset Press, HHP-2.
• Crown Race Puller, CRP-1. (other options describe in procedure below)
• Crown Race Installer, CRS-1.
• Degreaser, CB-2
• Measuring Caliper
• Rags

This article will discuss removing the old headset, installing and adjusting a new threadless headset. See also related articles:

• Threaded-type headsets, see Threaded Headsets.
• Cutting a fork to size, see Fork Sizing.
• Machining the fork crown see Fork Steering Column Milling.
• Headtube reaming and facing see Headtube Reaming and Facing.
• Headset types and nomenclature, including discussion of Low-Profile and Integrated Headsets, see Headset Type
• Installing threadless star-fangled nut see Installing Star Fangled Nut with TNS.
• Crown Race Removal see Crown Race Puller CPR-1

If you are confident the headset is properly installed and lubricated go directly to adjustment.

Bearings on a bicycle allow the parts to rotate relative to one another. The headset allows the fork to turn smoothly while riding. Bicycles, and all two wheeled vehicles, make small self corrections in steering while traveling forward. If the headset is pitted or worn, these corrections are not made smoothly and handling suffers. Very worn headsets tend to "lock up" when the front wheel is pointing straight. Pick up the front of the bike, and gently swing the handlebars back and forth from center. Pitting in the cups will cause the headset to stick as it passes through center position. A pitted headset should be replaced. New headsets are pressed into the frame and fork.

All bearings on a bike have some friction as they rotate. This is normal and does not affect the ride. Better quality bearing surfaces are ground smoother and will have less friction and resistance to turning. Adjustable type bearing systems use two opposing races which can be moved relative to one another. If the adjustment is too tight there will be too much pressure on the bearing surfaces and balls and the system will quickly wear out. If the adjustment is too loose there will be movement or "play" between the parts. This will cause a knocking in the bearing surfaces and again they will wear out prematurely. Generally, the bearings should be adjusted as loose as possible without play or knocking in the system.

The upper and lower bearing surfaces are connected by the steering column. The two bearing surfaces need to be parallel in order to operate smoothly. If the upper and lower surfaces of the head tube are not cut parallel, the bearings will tend to bind as the fork is rotated. This can lead to premature bearing wear and a less than desired adjustment. The head tube can become deformed by welding or simply less than adequate manufacturing techniques. The base of the fork steering column should also be cut square to the fork. If it is not properly machined, the fork crown race will not sit square to the steering column and will add to the binding effect. The head tube can be machined (faced) so the surfaces are parallel by using the HTR-1 Head tube and Racing Tool. The fork can be machined with the CRC-1 Crown Race Cutter. This process is best left to professional mechanics.

Threadless headset bearings are held secure by the stem. The upper adjustable bearing race will slide up and down on the steering column. The stem binder bolts hold the stem secure on the column, which keeps the race from moving. To adjust the race, the stem must first be loosened. There is a cap in the top of the stem that will apply pressure to the race when the stem is loose. A typical threadless headset on the bike, and the various parts are seen below.

Headset Removal

1. If possible, disconnect cables shift and brake levers. Loosen stem and remove bars and stem from steering column.

2. NOTE: If you are not removing bars completely, use care not to kink or damage housing when hanging bars on bike.
3. Remove any washers/spacers from steering column.
4. Pull fork from bike. It may be necessary to use mallet and tap top of steering column driving fork downward. Once fork is driven down as little as 25mm (one inch), lift fork back up and remove center cone from adjusting race. Remove fork.
5. Note orientation of bearing retainer (if any).
6. Install Park Too RT-1 Race Tool with small side first upward through the bottom of the headset cups. Squeeze sides of prongs and pull tool fully into head tube. Do not press with hand on bottom of tool, as prongs will close and pinch flesh. A clicking sound will be heard as tool engages head tube cup.

   

7. Use a hammer at end of RT-1 and drive cup from head tube. Use care as cup approaches end of tube, as tool may fall to ground on last blow of the hammer.

   

8. Place RT-1 with small end first through remaining cup and remove.
9. Remove fork crown race from fork. Use the Park Tool CRP-1. For specific use of CRP-1 see Crown Race Removal.

   

10. An optional procedure to the above is to drive the race off using a punch and hammer. In some cases this may scar the fork and crown race.

Installing Headset Bearing Races

Headset bearing races are held by an interference fit into the head tube. An interference fit occurs when parts are held together by internal and external surfaces forced together. There must be a slight diameter difference between the two pressed surfaces. Typically, the pressed headset race outside diameter should be between 0.1mm and 0.25mm larger than the head tube inside diameter. When the cups are pressed, the head tube will flex and enlarge slightly to allow the cups to press. This tension is what keeps the cups tight in the frame.

Use a caliper to measure the outside diameter of the cups. Next, measure the inside diameter of the head tube in two places, each 90 degrees from the other. Average the two reading. If the head tube more than 0.25mm smaller than the race, it may be reamed using the HTR-1 Headtube Reaming and Facing tool. If the race is between 0.01mm and 0.09mm, a different headset with a larger press race should be used. It is also possible to use a retaining compound such as Loctite® RC609. If the race is equal to or smaller than the head tube, a different race should be used. See discussion of press fit standards below.

The fork bearing race is pressed to the fork crown race seat. The fork race is smaller than the crown race seat. It is the race that expands as it is pressed. Races are commonly made of bearing steel, which tend to be very hard and brittle, and do not expand to the same tolerances as the head tube. The crown race seat should larger then the race by 0.1mm to 0.15. Much more difference may stress and crack the bearing race. When the crown race seat is too large for the fork crown race, it may be milled smaller with the CRC-1 Crown Race Cutter. If the crown race seat is only slighlty larger than the race, 0.02 to 0.09mm, use a retaining compound such as Loctite® RC609. If the crown race seat is equal to or even smaller than the race, use a different race. See discussion of press fit standards below.

Pressing Headtube Cups

This discussion will assume use of the HHP-2 Headset Press and the CRS-1 Crown Race Setter.

1. Determine the acceptability of the headset press fit as described above.
2. Adjust threaded press plate of HHP-2 until top is flush with end of hex shaft thread
3. Remove sliding press plate and install cups onto guides. Guides are used to maintain cup alignment while pressing. Cup guides fit most 1-inch and 1-1/8-inch standard headset cups. Before using cup guide, insert guide into cup. If guide appears to jam or is a tight fit, DO NOT use cup guides for that particular headset cup. Do not use cup guides #530-2 if guides press on any pre-installed cup-bearing unit (ex. Chris King® headsets). For headsets not fitting #530-2 cup guides, simply press using threaded press plate and sliding press plate. Pressure on the outer rim of aluminum head cups may visually scar the cups. If not using the guides, it can help to press one cup at at time.
4. Place upper headset cup on top of head tube. Hold one cup guide onto top threaded press plate and lower assembly through top headset cup.
5. Install second cup guide onto sliding press plate, and place lower cup onto guide.
   
6. Engage sliding press plate onto hex shaft, and push plate upward until headset cup meets head tube. Release lever. Sliding press plate lever must be engaged in one of seven hex shaft notches. Pull downward on lower press plate to test engagement.

   

7. Turn handle clockwise slowly and inspect alignment of cups as cups enter head tube. Continue and press cups fully into head tube. If threaded press plate has bottomed on threads of hex shaft, turn threaded press plate counter clockwise until it is again flush with top of threads. Re-engage sliding plate to a higher notch, and continue to press cups. NOTE: Never use a "cheater bar" to extend leverage of handles. If cups will not press using handles, other problems are present and should be addressed.
8. NOTE: If the headcup has pre-installed cartridge bearings, check that any guide will not press directly on the rotating bearing. For these types of cups, press only with the flat plates of the headset press. Press only one cup at a time.
   
   
   
   
9. Inspect for full seating where cups meet frame. A gap indicates incomplete pressing, as seen below.

   

10. Remove HHP-2 from bike. Unthread handle 1 turn, press lever of sliding press plate and remove tool from bike.

Pressing Fork Crown Race

The fork crown race must be pressed to the fork crown. Determine acceptability of press fit as described above. Place race on fork crown and select most compatible CRS-1 insert. Place tool and insert over fork. Use hammer and strike top of tool until race fully seats. The sound will change as it seats. Inspect sides of race for seating.

Installing the Star Fangled Nut

The threadless headset is adjust by pressure from the top cap. The adjusting bolt threads into the "star fangled nut". For nut installation, see Star Fangled Nut Installation.

Headset Assembly

If the headset is using bearing retainers, check the orientation of the retainers before installing. Retainers have only one correct orientation. The open side of the ball retainer should face the cone shaped race, not the cup shaped race.

It is possible to replace retainer ball bearing with loose bearings. Grease cups to hold bearings, and place balls into cup shaped races. Leave a wide gap the size to two ball bearings, do not attempt to fully fill cup.

1. Grease bearing retainers and bearing race cups. NOTE: Do not grease steering column.
2. Install bearing retainers into cup shaped races.
3. Place fork throug