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~LQu~d of the Invention This invention relates to an improved single wheel trailer for a bicycle, particularly an operator propelled single wheel trailer.
Single wheel bicycle trailers of various types are known in the art although they appear not to have met with a wide degree of commercial success, at least in North Ameri~a. The following patents exemplify the ~tate o the art:
3,787,065 Grimm 4,413,835 Hazelett - , , 4,458,90~ Strong ~ m~
15Canadian Patents 51,516 Jakobson 1,235,435 Bertrand . .
The broad concept o~ a.:.:tandem bicycle is not new reference being had to the Stron~ U.S. Patent~4,458,g08.
One might also refer to the old Canadian patent 51,516 dating from March 3, 1886. In both of these patents, the trailing bicycle uses elther its own forks or a modified set o~ forks. The Strong U.S. patent provides a special set of forks which are connected to the rear a~le of the leading bicycle with the upper end of the forks being provided with a universal joint permitting relative movement between the bicycles about three different axes, i.e. pitch, yaw~ and roll. The mechanism allows simultaneous tilting, bending and articulating between 3Q the two bicycle sections. The con~c~ion is of a somewhat complicated nature -invol~ing ~pring~ etc. which we need not describe in detail at the present time.
: The above li~t of patents al~o includes several single wheel trailer bicycle attachments. Reference may be had to U.S. patents 4,413,835, 4,756,541 and Canadian 1,~35,435. The Canadian patent, for example, discloses 2 ~ ~ 3 ~ d a connection between the trailer and the bicycle which permits relative movement between the bicycle and trailer about the pitch (horizontal) and yaw (v~r~ical) axes.
The reasons behind the lack of commercial success appear to be that, while certain of the prior art designs included ~ne or more useful features, no one seems to have been able to put together in one assembly that combination nece~sary to provide a high performance, stable, sae, simple and readily affordable operator-propelled single wheel bicycle trailer. The above-noted characteristics (of sa~ety and stability) are especially important when considering the fact tha young families will be using these trailer systems; a common arrangement will involve a parent driving the usual bicycle with th~
child on the trailer. Affordability and adaptability to virtually any commercially available bicycle are also key considerations for a commercially successful arrangement.
SummarY o~ the Inventlon A basic object of the invention is to provide a stable, safe, simpl~ and cost-affordable single wheel bicycle trailer which eliminat~s or at lea~t alleviates many of the disadvanta~es of the presently known prior art bicycle trailers of thi~ type.
The invention in its several aspects is defined in the claims appended hereto.
DescriPtion of the Views of Drawin~~
Fig. 1 is a side elevation view of the single wheel trailer o~ the present invention secured to a conventional bicycle;
Fig. 2 is a view, partly in section, of the connection between the trailer and bicycle;
2~3~6 Fig. 3 is a plan YieW of the connection of Fi~. 2;
Figs. 4 and S are ront and side elevations of the adjustable handle bar and its mounting;
Fig. 6 is a view similar to Fig. 1 ~howing a modified form of si~gle trailer (youth or child version).
Detailed Description Referring now to the drawings, there is shown in Figure 1, a single wheel bicycle trailer 10 in arcordance with one embodiment of the invention (the adult ver~ion) secured to a ~onventional bicycle 12. The trailer 10 includes a main frame 14 of welded tubular members, this main frame including a generally upright seat pos~ 16 with the trailer wheel 18 being rotatably mounted to frame members 20 rearwardly of the seat post 16. A
crossbax 22 is welded to and extends forward from an upper end portion of the seat post 16. A brace 24 extends downwardly and rearwardly ~rom the crsssbar 22 and i~ fixed relative to the lower end o~ seat post 16 to stabilize the crossbar. (The lower end of ~eat post 20 16 and the lower end of brace 24 are actually both welded to a housing (not shown) which rotatably mounts the conventional crank and sprocket as~embly 26~.
The arocsbar 22 has a forwardly directed elongated extension 28 which has a distal end 30. A flexi~le 25 connector 32 to be described in detail hereafter, is secured to distal end 30 to effect a connection to the bicycle 12. This 1exible connector 32 provides freedom of movement of the bicycle 12 and trailer 10 relative to on~ ano~her about mutually tran~verse pitch and yaw 30 axes.
Turning now to Figures 2 and 3, the seat post 16 is provided with an upwardly extending ~tem 34 which ~upport~ a con~entional b1cy~le ~eat 36. The }lexible .
connector 32 includes a bracket 36 mounted on the stem and rotatable about the longitudinal axis of the stem to provide the above-noted freedom about the yaw ax~. In order ko facilitate this rotating motion, the bracket and stem are provided wi~h upper and lower ball bearing ~ssemblies 38 and 40 with the stem being provided with an annular shoulder 42 which limits the downward mov~ment of the bracket and its bearing assembly. The ~tem is also thread~d as at 44 to accommodate a lock nut 46 which secures the whole bearing assembly together.
The trailing end portion of bracket 36 is bifurcated and ~haped to receive the distal end portion 30 of the crossbar extension 28. A pivot pin .~0 defines the horizontal transverse pivot connection betw2en bracket 36 and the distal end of the extension 28 thereby to proYide the above-noted freedom o movement about the pitch axis.
It might be observed here that the angle of incline of the seat post 16 and stem 34 relative to the horizontal provides for a natural castering effect of the flexible connector thereby reducing side thrusts during operation. When the lead bicycle leans to go around a corner, the trailer tends to lean slightly opposite (about 15). In the sharpest corner the lead bicycle might be expected to negotiate, the trailer be~omes ~enerally vertical. This factor makes for greater stability, a~; in a situation where the road is slippery and excessive leaning could cause the wheels to slide out ~rom underneath the rider.
With reference to Figures 4 a~d 5, the trailer is provided with a handle b~r 54 which is secured to the crossbar 22 hy way of a handl~ bar mounting stnlt 56.
The strut comprises an elorlgated bar o~ metal of 'che correct approximate length which is provided at its lower end with a semi-circular recess 58 to receive the cros~
35 bar. A corresponding cap portion 60 also has a 2~53~4g corresponding semi-circular rece~s therein, the cap 60 being secured to the mounting strut 56 via cap screws 62 and which, when tightened, securely fix the mountiny strut 54 relative to the trailer frame. By loosening cap screw 62, the mounti.ng strut 56 c~n be slid toward and away from the seat 36 thereby to accommodate differently sized riders.
The upper end of strut 56 is provided with transverse aperture to receive the handle bar 54 with a slot 64 leading into the aperture and a cap screw 6~
being provided to securely fix the handle bar 54 relative to the strut 56.
It might be noted that, as illustrated in Fig. 1, when the trailer is attached to the leading bicycle, the crossbar 22 inclines slightly upwardly and forwardly from the ~eat post 16. Hence, as the handlebar mount is adjusted away from the seat po~t, the handlebar is automatically raised upwardly thereby to better accommodate lar~er riders on the trailer. The seat 36 can of course be raised and lowered .in conventional ~ashion to accommodate larger or smaller riders as the case may be. This situation is more pronounced in the F.ig. 6 version where the crossbar 122 is secured to an intermediate portion of the seat post 116 and slopes steeply upwardly and forwardly therefrom. This provides greater degree of height adjustment for the handle bar~
and makes this version more suitable for small size (childrens) frames.
The trailer 10 is also provided with a conventional crank and sprocket means 26 drivingly connected to the conventional cycle wheel 18 by chain and ~procket assembly 60. ~he chain drive assembly is typically provided with a conventional gear change mechanism compatible with the gear change m~chanism on the leading bicycle for obvious reasons.
~ 3 While a preferred embodiment of the invention has been described by way of example, those skilled in this field will realize that numerous modifications and changes may be made while still remaining within the scope of the lnvention. Accordingly, the invention is not to be limited to the speciic embodiment described but is to include all modifications and variations as fall within the scope of the accompanying claims.