With an integrated chain stabilizer mechanism, the Shimano GRX derailleur provides a quieter experience while delivering shifting security and precision on mixed terrain. For rides on smooth surfaces, the derailleur features an ON/OFF switch for the chain stabilizer. The RD-RX810 rear derailleur is compatible with road cassettes with a max cog size of 34T. - Adjustable, gravel-tuned chain stabilizer prevents chain slapping and drops - Switch stabilizer ON/OFF to match the terrain - Silent and uninterrupted rear shifting on rough terrain - Low cog: Max. 34T/Min. 30T - High cog: Max. 11T/Min. 11T - Total capacity: 40T - Compatible with current road Dual Control Lever - Maximum front chainring range: 17T