Adopting the technology introduced in 2018 in the rear changes, the GRX Di2 rear derailleur (RD-RX815 / RX817) has been designed to make silent, smooth and reliable changes on difficult terrain thanks to the system of SHADOW RD + chain stabilization, which minimizes unnecessary arm movement and provides uninterrupted performance. GRX comes with four options, depending on the cassette and gearshift you prefer. Cyclists who use the 11-30 / 34T cassette with Ultegra, 105 or Tiagra, will need the Di2 RD-RX815 rear derailleur or the RD-RX810 mechanical, while those who opt for the 11-40 / 42 cassette For Deore XT, SLX or Deore you will need to use the Di2 RD-RX817 or RD-RX812 mechanical, both with a cable shot similar to the SHIMANO road changes.
Adjustable chain stabilizer that prevents bumps and falls in the chain: SHIMANO SHADOW RD +
Soft and reliable mixed surface change
Compatible with current road. DUAL CONTROL LEVER
The GS model allows cassettes of up to 34 teeth
The SGS model allows cassettes of up to 42 teeth