The Shimano GRX BR-RX820 is the rear hydraulic disc brake caliper from Shimano's 12-speed gravel groupset, built to deliver controlled, predictable stopping on loose and variable terrain. The two-piston flat mount design pairs strong power with the fine modulation gravel riders rely on when surfaces change without warning.

• Rear flat mount caliper from the GRX RX820 12-speed gravel groupset
• Two-piston hydraulic design running mineral oil
• Supplied with L05A-RF resin pad with cooling fin for improved heat management
• 10% wider pad clearance helps reduce brake rub and noise
• One Way Bleeding system makes servicing quicker and cleaner
• Compatible with 140 mm and 160 mm rotors

Gravel-focused control

Tuned for off-road riding, the BR-RX820 gives a quick initial bite followed by progressive modulation, so you can scrub speed with confidence on descents, gravel and mixed surfaces. The finned L05A-RF resin pad sheds heat on long descents while keeping operation quiet.

Easier to live with

The wider pad clearance reduces the chance of disc rub after wheel changes, and Shimano's One Way Bleeding system streamlines maintenance by helping push air bubbles cleanly through the system.

Compatibility & fit

This is the rear caliper only. It uses a flat mount interface and accepts 140 mm or 160 mm rotors (a mount adapter or bracket may be required depending on rotor size and frame). It runs on mineral oil and is designed to work within the Shimano GRX 12-speed (RX820) hydraulic system with compatible GRX shift/brake levers. In the standard Australian setup the rear brake is operated by the left-hand lever, so this rear caliper pairs with the left lever. Brake hose is not included.