Derailler system

摘要

A derailler system for a bicycle including a sprocket system having a plurality of drive sprockets and a chain for driving a wheel of the bicycle at different speeds with the chain being shifted onto individual drive sprockets by movement of an idler sprocket. A movable carrier member has the idler sprocket rotatably mounted thereon for selectively shifting the chain and a guide system is provided for guiding movement of the carrier member along the path essentially parallel with the axis of the driven wheel. A shifting mechanism for actuating the guide system includes a shift lever enabling shifting of the movable carrier to a plurality of shifting positions corresponding with the drive sprockets and a cam follower member including a cam follower rotatably mounted on a first part of the guide system is arranged to engage a cam member mounted on a second part of the guide system which is movable relative to the first part. The shift lever operates through a transmission mechanism to effect rotation of the cam member relative to the second part in order to move the guide sprocket to any one of a desired plurality of positions. A first spring is connected to urge the cam follower into contact with the cam member thereby to move the movable carrier member along its path of travel whenever the cam plate is rotated and a second spring biasing the cam follower member to a position relative to the first part is also provided with the relative position being defined by a stop member on the cam follower member and by a cooperating counterstop member on the first part of the guide system.