US Patent 8202182 Motion resisting apparatus for a bicycle derailleur

A bicycle derailleur apparatus comprises a base member for coupling to a bicycle frame, a movable member coupled for movement relative to the base member, a chain guide coupled to the movable member for guiding a chain among a plurality of sprockets in response to movement of the movable member, and a biasing device that provides a biasing force to the chain guide for tensioning the chain. A movement resisting device has a control element for the application of a signal that causes the movement resisting device to change resistance to movement of the chain guide.