As the name suggests, shift levers are used to initiate the shift operation. Modern shifters indicate clearly and noticeably a gear change and are therefore referred to as index or trigger shifter. With just a little finger movement, the chain moves in fractions of a second to the desired chain ring and the right gear ratio for acceleration, for uphill or downhill sections is set. Meanwhile, it has been established that the left shifter controls the chain on the front chainwheel and the right one on the rear sprocket. In addition to shifting levers, there is also the option of initiating and controlling the shifting operation by twist-grip switches. However, rotary handle switches are often used for hub gears.
