| 摘要 |
<p>This invention relates to a multi-stage chain wheel which is fitted to a pedal crank of a bicycle and is used for transmitting driving force generated by a rider to a rear gear through a chain. The following countermeasure is taken in order to prevent the chain from locking a large diameter sprocket (1) and from falling off from the sprocket before it shifts completely onto a small diameter sprocket (2) when the chain is shifted from the large diameter sprocket to the small diameter sprocket. Namely, gears at least one of a portion (A1) crossing the crank arm (4) of the pedal crank when viewed on the side surface and a portion (A2) facing this portion (A1) in a diametrical direction across the axis of the sprocket are asymmetric gears (tx) in a longitudinal direction wich are deviated forwardly in the rotating direction with respect to the center of the pitch of the gears of the large diameter sprocket (1) in comparison with other ordinary gears.</p> |
