Patent ID: 7104908
Filing Date: 2006-09-12
Classification: B62M

Abstract:
1. A rear bicycle derailleur, comprising: a base member having an installation area adapted to be mounted to a bicycle frame; a movable member; a pair of parallel links interposed between said base member and said movable member to form parts of a parallel link mechanism together with said base member and said movable member such that said movable member is movable relative to said base member between a retracted position and an extended position; a guide arm pivotally coupled to said movable member so as to be freely rockable around a first rocking axis without being rotationally biased in a predetermined rotational direction; a guide sprocket provided on said guide arm that is freely rotatable around a first rotation axis parallel with said first rocking axis; a tension arm pivotally coupled to said movable member so as to be rockable around a second rocking axis; a tension sprocket provided on said tension arm that is freely rotatable around a second rotation axis parallel with said second rocking axis; and a biasing spring provided between said tension arm and said movable member in order to bias said tension sprocket in a rearward direction relative to the bicycle frame.