High Quality Content by WIKIPEDIA articles! 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, on the handlebars, or at the ends of triathlon bars. Major manufacturers of shifters include Shimano, Campagnolo, and SRAM.