Gear-shift control bicycles and similar vehicles

Gear-shift control of bicycles and the like, of the "derailleur" type with guiding means (13, 14;

• 52) for chain (3) that can be moved crosswise (arrows 23, 53) between at least two separate positions by a traction element such as a cable (12) from an actuating means such as a shifter (8) located remotely;
• characterized in that it comprises essentially, in combination:
• a mobile element (26) that receives the movement of the traction element such as cable (12),
• a mobile toothed element (24), connected in its movements to guiding means (13, 14;
• 52) of chain (3) and comprising teeth (44) whose number at least equals that of the separate positions occupied by said guiding means of the chain,
• a memory element (31, 32) carried by receiving element (26) and working with the teeth of toothed element (24) and
• swinging means (40, 41, 42, 43) acting on memory element (31, 32) during its movements that accompany those of receiving element (36) so that, for a movement of the traction element such as cable (12) with a small amplitude, followed by a release, toothed element (24) is moved in a first direction along a path corresponding to the interval between two teeth (44) and, for a movement of traction element such as cable (12) of a greater amplitude, still followed by a release, toothed element (24) is moved in a second direction also along a path corresponding to the interval between two teeth (44).