The RD-RX820 is compatible with the 12-speed cassettes 11-34Z and 11-36Z, providing a wide gear range that allows for a comfortable cadence in any terrain. The SHIMANO GRX 12-speed derailleur also features an integrated chain stabilizer that ensures quieter shifting and safer chain management when the going gets rough. The chain tensioner is equipped with an ON/OFF switch for rides on smooth surfaces.