| 摘要 |
<p>The derailleur includes a relatively long, torsion-resisting bar (29) extending below and generally along one of the two rear wheel-supporting bicycle frame members (15). In a simple embodiment, the front end (31) of said bar is held by a fastener secured to the bicycle frame adjacent the housing of the pedalling axle. The holder prevents the bar from rotating about its long axis. The rear end (57) of the bar is movable transversely of the frame member by a remote control actuator. The bar carries a drive chain transfer member (55) and a chain take-up device (59) which serve to transfer the drive chain from one to another rear drive sprocket, while taking up the slack in the chain. In a preferred embodiment, the chain take-up device (59) comprises an elongated member extending along and below the bar, movable longitudinally along and guided by said bar and carrying at its rear end a drive chain tensioning member (67). The elongated member is biased rearwardly by an elastic cord (69). The bar is movable back and forth under the action of a remote controlled cable and its rear end carries a hook (45) selectively engaging anyone of several positioning recesses (53) made in a plate fixed to the frame member. The recesses are disposed side by side along an edge of a slot (47) made in the plate and through which the hook (45) extends. The slot is transversely inclined being parallel to the envelope of the rear drive sprockets. Longitudinal movement of the bar positions the drive chain transfer member in alignment with the selected drive sprocket.</p> |
