Patent ID: 7549662

Claim:
A bicycle gear mechanism, comprising a derailleur provided with a drive chain guide element, the derailleur being predisposed to rotate on command with respect to a bicycle frame in such a way as to translate a drive chain between a plurality of gears which are coaxial to a wheel of the bicycle, in a parallel direction to a rotation axis of the gears, wherein the derailleur ( 1 ) comprises: an arm ( 2 ) which exhibits an elongate shape and which has a longitudinal axis (x); a first attachment element ( 5 ), rotatingly constrained to the arm ( 2 ) by a first shaft ( 3 ) which is rotatable on command with respect to the first attachment element ( 5 ), the first attachment element ( 5 ) being predisposed to connect the arm ( 2 ) to the bicycle frame; a second attachment element ( 6 ), rotatably constrained to the arm ( 2 ) by a second shaft ( 4 ) which is parallel to the first shaft ( 3 ) and solidly constrained to the second attachment element ( 6 ), the second attachment element ( 6 ) being predisposed to connect the arm ( 2 ) to the drive chain guide element to guide the drive chain of the bicycle; a connecting mechanism predisposed to rotatingly connect the first shaft ( 3 ) and the second shaft ( 4 ); and at least an actuator, operatively connected to the arm ( 2 ) and the bicycle frame, which actuator is predisposed to rotate the arm ( 2 ) about the first shaft ( 3 ).