Method of determining the transmission ratios for a bicycle chain shifter and shift device for implementing the ratios thus determined

摘要

The mechanism comprises a rotary control handle (18) connected to a barrel (16) with two tracks (30,32) to receive nipples fastened to the ends of cables (44,46). the cables operate the chain wheel and sprocket chain shifters. The barrel (16) is in the form of a hollow cylinder with the tracks (30,32) on its inner and outer surface. Each of the cable nipples is in the form of a roller (66,68) which rolls in the corresponding track and is connected to the cable by a curser. Each of the cables can also be equipped with a coaxial compensating spring between a fixed stop on the handle and the corresponding nipple. Each spring is long and spiral in shape, of small diameter and rigidity, providing a sufficient compensating effort for minimal dimensions.