• Shimano GRX Di2 RD-RX825 12-Speed Rear Derailleur
  • Shimano GRX Di2 RD-RX825 12-Speed Rear Derailleur


Shimano GRX Di2 RD-RX825 12-Speed Rear Derailleur



The Shimano RX825 Rear Derailleur features Shimano's pioneering Shadow RD+ technology. With its convenient on/off switch, Shadow RD+ makes removing the rear wheel easy when turned off. When on, the drivetrain is under additional tension that makes for a quieter ride and more precise shifting.

Like on Shimano's road 12-speed Di2 systems, the rear derailleur is also the communication hub of the drivetrain, communicating wirelessly with the shift levers, compatible cycle computers, and E-TUBE PROJECT Cyclist via a smartphone. It also houses the system's charge port and the multi-function button which allows riders to easily check battery level, pair via Bluetooth, and enter adjustment mode for both derailleurs.

Using Shimano's E-TUBE PROJECT Cyclist application, riders can choose between different gear shift intervals for multi-shift, customize shift button assignment (what buttons perform which functions), program different automatic shift modes like Synchronized and Semi-Synchronized shifts, and fine-tune shifting.


  • SHIMANO SHADOW RD+ Chain Stabilization
  • Integrated D-FLY Connectivity and Charging
  • 12-speed
  • Compatible with 11-34T and 11-36T cassettes
  • 310 grams