Electronic gear-shifting system

An electronic gear-shifting system is a method of changing gears on a bicycle, which enables riders to shift with electronic switches instead of using conventional control levers and mechanical cables. The switches are connected by wire or wirelessly to a battery pack and to a small electric motor that drives the derailleur, switching the chain from cog to cog. An electronic system can switch gears faster, and because the system does not use Bowden cables and can calibrate itself, it may require less maintenance.

In 1990 the Japanese bike component manufacturer SunTour introduced the Browning Electronic AccuShift Transmission (SunTour BEAST) - a triple chainset system for mountain bikes in which one quarter of the circle is hinged along a radius. During shifting, this segment is pushed sideways by a relay operated mechanism like a railroad switch and picks up the chain that is currently running on the next cog.

In 1992 the French manufacturer Mavic introduced their first electronically controlled gear shift mechanism called Zap at the 1992 Tour de France. It was a prototype, but it achieved neither technical success nor commercial application. A development of this was used by Chris Boardman to win the opening time trial (prologue) of the 1997 Tour de France.

In 1994 Sachs introduced the Speedtronic.

In 1999 Mavic introduced the Mektronic, its second electronic shift system, which suffered from reliability issues and was subsequently discontinued.

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