A
bicycle shifter or
gear control or
gear levers is a component used to control the gearing mechanisms and 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,
stem, or various locations on the
handlebars. Manufacturers of shifters include
Shimano,
Campagnolo, Microshift, Sturmey Archer, and
SRAM.