Patent ID: 8066597

Claim:
A derailleur comprising: a base member; a movable member; a linkage mechanism including a link member coupled to the base member and to the movable member so that the movable member moves relative to the base member; a motor that drives a drive member; a driven member driven by the drive member, wherein the driven member is coupled to the link member so that the link member moves relative to the base member to move the movable member relative to the base member; and a clutch disposed in a power transmission path between the motor and the link member; wherein the clutch selectively disengages power transmission between the motor and the link member when a power transmission force is applied by at least one of the motor or the link member; wherein the driven member pivots around a fulcrum, wherein the driven member includes a first extension and a second extension, wherein the first extension has a clutch bearing surface for providing the clutch engagement force, wherein the second extension has a bias receiving location for receiving a biasing force, and wherein a ratio of the distance between the fulcrum and the bias receiving location and the distance between the fulcrum and the clutch bearing surface determines the magnitude of the engagement force of the clutch when the clutch is engaged.