A bicycle shifter, also known as a gear control or gear lever, is a component used to control the gearing mechanisms and to select the desired gear ratio. Typically, they operate either a derailleur mechanism or an internal hub
gear mechanism. In either case, the control is operated by moving a cable that connects the shifter to the gear mechanism. Shifters are mounted on the down tube
of the frame,
on the handlebars,
or at the ends of triathlon bars. Major manufacturers of shifters include Shimano, Campagnolo, and SRAM.
The controls are mounted so that the right shifter controls the rear derailleur
and the left shifter controls the front derailleur.
gears, the control is also mounted on the right.
The trend in shifting development has been to reduce the need for the rider to direct attention away from riding. Friction shifters gave way to index shifters, which do not require fine-tuning during a gear change.Full Article