Derailleurs

Shimano's electric-shifting 11-speed Ultegra Di2 Rear Derailleur is driven by battery power and a servo motor, so shifts are fast, precise, and perfect every time. It's made of light, tough cold-forged aluminum while mid-cage and short-cage models give you your choice of cassette. Since there aren't any cables or housing to stretch or fail, maintenance is dramatically reduced and shifting accuracy is unprecedented. This high-tech derailleur is even designed to move inward under impact to reduce the potential for damage in a crash.

Shimano Ultegra Di2 Shadow rear derailleur. - Sleek integrated appearance - New low-profile design - Shimano Shadow RD - Race endurance - Optimized slant angle - Maintain race concentration with more intuitive shift control - System communication with front derailleur - Shimano Synchronized Shift - Wide compatibility - Short cage covers: 11-25T to 11-30T - Medium cage covers: 11-28T to 11-34T - Average Weight: 242 grams (SS type), 249 grams (GS type)