Shifting Gears (Electronically)

How Shimano's new shifting systems makes changing gears faster, easier and more accurate

Last year bicycle manufacturer Shimano debuted its years-in-the-making electronic gear shifting system, the Dura Ace 7970 Di2. Electronic shifting, which replaces traditional steel cables with a precise CPU-controlled system of sensors and motors, had long been a goal of bike makers. A workable solution, however, proved elusive. So when Shimano finally got it right with the Dura Ace system, it earned PopSci's 2008 Best Of What's New Grand Award in the Recreation category.

The system is catching on among professional cycling teams, who have used it in the Tour de France, among other big races. The company is now implementing it in an increasing number of high-end bikes, with the hope that eventually even casual cyclists will want the improved shifting accuracy and ease of use. Here Shimano spokesman Devin Walton walks us through how it works.