MECHANICAL SPEED-CHANGING SYSTEM FOR BICYCLES AND SIMILAR VEHICLES

摘要

The invention relates to a mechanical speed-changing system comprising a front axle (2) with pedals and a rear tubular axle (3) which receives the movement from the front axle via pairs of sprocket wheels which intermesh and which are connected to said axles. Moreover, said axles are coupled to a frame (1) which, together with the rest of the constituent speed-changing elements, forms an independent unit (32) which is tightly housed inside a groove (33) corresponding with the pedal axle. The rear axle comprises idler gears (9) which mesh with other idler gears (10) that are solidly connected to a coaxial tube (11) which is freely connected to the front axle, said tube also being fixed to a plate (16). In addition, the inventive system comprises devices for the selective blocking of the idler gears and the sprocket wheels (6', 7') of the rear axle. The invention is also characterised in that the idler gears (9) form a floating assembly through the inclusion of bearings (39) which prevent friction between same.