US Patent 7086974 Actuator for a bicycle gear-shift

A bicycle gear-shift actuator (10, 100) having an articulated quadrilateral support (11) with four connecting rods (21, 22, 23, 24) hinged together by four pin elements (41, 42, 43, 44), and a motor member (12), having a variable length output shaft that travels along a drive axis (13) between two opposite pin elements (41, 42) to move them for deforming the articulated quadrilateral (11). Preferably, the drive axis (13) perfectly intersects the pin axis (32) of at least one (42) of the two pin elements (41, 42).