Derailleur gear for bicycle - has parallelogram linkage pivoted to cycle fork with tensioning and guide rollers

摘要

The derailleur gear for a cycle comprises a parallelogram structure (5,8,9,12) pivotably mounted to the cycle fork by a lug (1). Arm (12) carries the chain guide roller (15) and tension roller (16) in a yoke (14). Tension in the traction cable (24) causes the structure to move between the end positions. Respective adjusters (18,19) abut extensions (5a,12a) of the links (5,12). During movement of the structure, it is guided to remain close to the gear wheels by the action of a cam follower (21) riding along a cam surface carried by the support. Alternatively the cam follower is a truncated conical roller riding along a cam surface for guidance in three dimensions.