| 摘要 |
<p>The crank has sprockets which can be relatively positioned. There are three of these fixed on the crank axis and they are positioned automatically by pedal force, following the variable angular direction of the drive chain made by its position on one of the sprockets on the rear wheel free wheel. The crank (2) is coupled to a chain wheel (1) with peripheral teeth to mesh transversely with teeth inside a movable crown for the sprockets. Soft, opposed joints (4) on either side of the sprocket between cheeks (5) allow movement.</p> |
