Shimano Duraace RD-R9150 Di2Rear Derailleur Welcome to the next generation of roaddrivetrains.Dura-Ace R9100 is ready tochange your idea of how greata racingbicycle can perform. Electronic shifting offers some of the smoothest and most technologically advanced shifting available. The all-new redesigned Shimano Dura-Ace RD-R9150 Rear Derailleur takes advantage of Shimano's Shadow RD architecture, first introduced for mountain bikes. The low profile not onlygives it a sleek look while also providing extra damage protection in case of a crash but improves system stiffness for maximum shift performance.Combined with Shimano's Di2Synchro Shift customizable programming that automatically handles front and rear shifts to give you perfectly sequential ratios, DURA-ACE Di2 delivers a level of intuitive shift performance never before seen. Features ShimanoSynchronized Shift Compatible Compatible with new wide-range11-30T 11 Speed Dura-Ace Cassette Simplified shifting options Shimano Shadow RD low-profile design, also allows fordirect mount with special hanger Pulley maintains consistent distance to cassette for increased shift stability Tucked design results inless damage in a crash, but maintains compact and smooth appearance Total capacity: 35T Weight: 204g | Shimano Dura-Ace R9150 Rear Derailleur 11 Speed, Di2, Shadow