The BR-RX820 flat mount calipers pair with the levers via pre-bled SM-BH90 hydraulic hoses. These calipers feature 10 percent wider pad clearance than the previous generation, which addresses the brake noise complaints that plagued earlier GRX brakes. The included Ice Tech finned pads dissipate heat through aluminum cooling fins, maintaining consistent braking during extended descents. The bleed port repositioned to the caliper's outboard face simplifies maintenance when service is eventually needed.

The RD-RX820 rear derailleur handles the 11-36T cassette range with Shadow RD+ technology that tucks the mechanism close to the frame and includes an adjustable clutch to maintain chain tension over rough terrain. The clutch tension is calibrated for gravel riding rather than mountain bike use, providing enough resistance to prevent chain slap without making wheel removal difficult. An on/off switch lets you disengage the clutch when needed. The FD-RX820 front derailleur uses toggle link construction for consistent front shifts even under pedaling load.

The CN-M8100 chain is the same 12-speed chain Shimano uses across its Ultegra and Deore XT groupsets. SIL-TEC coating on the roller and pin link plates reduces friction and improves durability. This chain works with both the HG cassette in this kit and Micro Spline cassettes if you later switch to a 1x setup with wider-range gearing.

What's not included matters for planning your build. You'll need a GRX 2x crankset (FC-RX820-2 for 48/31T gearing or FC-RX610-2 for 46/30T), a 24mm Shimano-compatible bottom bracket matched to your frame's shell, and Center Lock disc rotors in your preferred sizes. The RT-CL800 rotors are the natural pairing, though any Shimano-compatible rotor works. This kit gets you the components that are hardest to find individually, leaving you flexibility on the parts that depend on frame specifications and rider preference.