A hub odometer is disclosed, which includes: an eccentric weight rotably supported in a center axis position of an axle hub; a case attached to the axle hub to surround the eccentric weight; a non-contact measuring mechanism disposed to measure the number of revolutions in a relative relation to the...http://www.google.com/patents/US6547128?utm_source=gb-gplus-sharePatent US6547128 - Hub odometer
