Speed change control unit for a bicycle provided with a transducer device and transducer device used in this unit

Speed change control unit for a bicycle, comprising a rotor, carrying a pulley for winding a cable driving the speed change device, said rotor being rotatably mounted within a body supporting a brake lever of the bicycle and being provided with indexing means defining the operative positions of the rotor corresponding to the various transmission ratios which can be selected with the aid of the speed change device, said unit further comprising two rotor driving levers located at positions which can be easily reached by the fingers of the hand of the cyclist without substantially modifying the position of the hand on the bicycle handlebar, said levers being adapted to cause rotation of the rotor in the two opposite directions respectively, with the aid of respective ratchet means associated with said rotor,

• wherein with said speed change control unit there is associated a transducer device adapted to transmit an electric signal indicative of the operative position of the rotor, said transducer device being mounted within an auxiliary supporting body which is provided with means for securing to said body supporting the brake lever, said auxiliary supporting body carrying also a button at a position which can be easily reached by the fingers of the hand of the cyclist, which button is to be electrically connected to an electronic unit of the bicycle, to enable a mode of operation of said control unit or a displaying mode on an on-board display connected to said electronic control unit to be selected.