The controls of front speed change devices (at the crank gear) or rear speed change devices (pinions of the free-wheel cluster) are effected generally by means of a cable system activated by a lever and which acts on a member of the speed change device for displacing the chain.
The displacements of the cable and as a consequence the pivotable movements of the lever or equivalent control member are different according to whether the lever controls the front speed change device or the rear speed change device or even according to the types of speed change devices. For these reasons, the levers utilized must be specially constructed as a function of the controlled speed change device.
It is, therefore, necessary to manufacture a plurality of types of levers which is very costly. It is necessary to have a storage capability and corresponding distribution facilities. Complications and difficulties result therefrom.