GRX RX820 12-Speed Rear Derailleur
GRX RX820 12-Speed Rear Derailleur, The Shimano GRX RX820 12-Speed Rear Derailleur delivers quiet, stable shifting as we ride over mixed-terrain on our 12-speed GRX gravel drivetrain. Shimano's Quiet and Secure technology creates a low-profile design, reduces chain slap, and improves chain retention, while the ON/OFF stabilizer switch matches the terrain for optimal performance.