Shimano GRX RD-RX825 Di2 Rear Derailleur – 12-Speed Long Cage With Clutch For 2x Black. Shimanos GRX RX825 Di2 12-speed rear derailleur features a built-in wireless connectivity unit and charging port ensuring fast and reliable shifting for mixed-terrain riding and easy recharging. Integrated Shadow RD+ technology prevents chain slap and ensures precise shifting even on rough terrain. Thanks to built-in ON/OFF switch wheel removal is easy too. The RD-RX825 is compatible with 11-34t and 11-36t 12-speed cassettes and supports Full or Semi-Synchronized shift modes enhancing rider customization.

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