Control device for a bicycle derailleur comprising spring means opposing the derailleur spring

Control device for a bicycle derailleur, comprising:

• a support body, to be fixed to the bicycle handlebar,
• a rotor rotatably mounted on the support body and provided with means for winding a flexible cable for controlling the speed change,
• indexing means for defining a plurality of stable positions of the rotor corresponding to the various speed ratios, said means comprising a toothed wheel fixed to the rotor and at least one resilient element carried by the support body and able to engage into vanes between the teeth of the toothed wheel,
• a pair of ratchet devices associated with said rotor and controlled by two respective control levers, for causing rotation of the rotor in two directions of rotation, respectively,
• wherein between the support body and the rotor there are interposed spring means tending to exert on the rotor an action opposite to that exerted by a return spring of the derailleur through the control cable and
• wherein said spring means are constituted by a spiral spring arranged in a plane perpendicular to the axis of the rotor and having end tails respectively anchored to said support body and said rotor.