Patent ID: 7189173
Filing Date: 2007-03-13
Classification: B62M

Abstract:
1. A front derailleur for a bicycle, the bicycle having a chain, a chain wheel, a control cable, and a seat tube, the front derailleur comprising: a) a frame bracket connected to the seat tube and located adjacent the chain wheel, the frame bracket having two lugs extending from a side thereof; b) a chain guide having: c) a linkage rod being pivotally connected to the two lugs at a first end thereof and pivotally connected to the pivot joint at a second end thereof; and d) an actuating arm pivotally connected to the frame bracket by a shaft having a return spring providing a restoring force, the actuating arm having: wherein a movement of the chain guide is controlled by the control cable to move the chain between at least a highest speed mode and a lowest speed mode, when the chain guide is in the highest speed mode, the linkage rod is located at a position substantially parallel with the seat tube and the restoring force of the return spring is equal to an active component force required for shifting the chain and the entire restoring force is utilized for down- shifting the chain from the highest gear to the middle gear.