| 摘要 |
A derailleur for a bicycle is provided that is easy to operate. The derailleur basically has a mounting member, a chain guide and a chain guide positioning mechanism. The mounting member is adapted to be coupled to a portion of the bicycle. The chain guide is movably coupled to the mounting member. The chain guide is adapted to shift a chain of a bicycle in a transverse direction. The chain guide positioning mechanism has an actuating cam operatively coupled to the chain guide. The actuating cam is adapted to be coupled to a control element such as a cable. The actuating cam is arranged to rotate only in one direction in response to movement of the control element to move the chain guide from a first position to a second position. In the preferred embodiment, the chain guide positioning mechanism includes one-way clutch coupled to the actuating cam, and an indexing mechanism with an indexing element that is arranged to operatively apply a retaining force to the actuating cam. The one-way clutch has a ratchet fixedly coupled to the actuating cam and an actuating element with a pawl engaging the ratchet. The actuating element is adapted to be coupled to the control element such that the control element rotates the actuating element, which in turn engages the ratchet to rotate the actuating cam and moves the chain guide.
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