The Shimano GRX 820 SGS Rear Derailleur is an essential component to ensure the smoothest possible shifting on your favorite gravel bike. This derailleur manages a 12-speed system with ease, providing near-silent function and seamless gear changes. It is equipped with Shadow RD+ Technology which is responsible for its silent function as well as a chain stabilizer that can be turned on and off. This reduces chain slap and chain drop and is lighter and more efficient than a roller type chain device. It can be switched off to provide a more pleasant ride on smoother surfaces. The SGS version is compatible with your 10-51T 12-speed MTB or gravel cassette, giving you tons of gearing options. The Shimano GRX 820 Rear Derailleur is a must have for gravel riders.