The Shimano GRX ST-RX825 shift/brake lever paired with the BR-RX820 flat-mount caliper delivers an elite, race-ready control package for mixed-terrain cyclists. Engineered to handle rough Australian gravel roads, the wireless Di2 dual-control lever features gravel-specific ergonomics. Its raised hood profile, ribbed surface texture, and anti-slip coated lever blades provide unmatched security when riding through mud, dust, or heavy corrugations. The hood body is uniquely rounded to eliminate uncomfortable pressure points when paired with modern flared drop bars. Running on two user-replaceable CR1632 batteries, the lever offers a wireless cockpit layout with an exceptional three-to-four-year battery life.
Down at the wheel, the BR-RX820 hydraulic caliper brings an entirely new level of control to off-road deceleration. Equipped with Shimano’s proven SERVO WAVE technology, it provides a quicker initial braking point followed by deep, highly progressive modulation. The caliper’s updated internal construction offers 10% wider brake pad clearance compared to previous generations, which significantly reduces annoying rotor rub from trail grit or heat expansion. Full compatibility with Ice Technologies finned brake pads ensures rapid heat dissipation, preventing brake fade on long, steep descents. Combined with an auxiliary third button on the inner hood and Front Shift Next technology, this pre-bled or J-Kit-ready system maximizes both customization and raw stopping confidence.
Wireless Di2 Integration: Eliminates electronic cables routing through the frame to the handlebars for a perfectly clean, easy-to-install cockpit layout.
SERVO WAVE Braking Power: Provides immediate initial pad engagement followed by fine-tuned modulation, giving you absolute control over technical, loose descents.
Wider Pad Clearance: Features a 10% wider gap between the brake pads and the rotor, dramatically lowering the chances of grit scoring or rotor drag on dusty trails.
Gravel-Specific Grip: The heavily textured hood covers and anti-slip brake blade coating guarantee your hands won’t slide off, even in pouring rain or deep mud.
Customisable Cockpit Controls: Built-in inner hood buttons can be mapped via Shimano's E-TUBE app to execute front derailleur shifts, control bike computers, or swap GPS pages.
Ice Technologies Compatibility: Works alongside finned cooling pads to channel heat away from the caliper, ensuring consistent brake performance without fade.
Series: Shimano GRX Di2 RX825
Speed: 12-Speed (Wireless transmission to Di2 rear derailleur)
Brake Caliper Type: Hydraulic Disc Brake (Flat Mount)
Brake Fluid: Shimano Mineral Oil
Pistons: 2-Piston Design
Standard Brake Pads: L05A-RF Resin (With aluminum cooling fins)
Lever Adjustability: Reach Adjust & Free Stroke Adjust
Connectivity: 1 x SD300 port, 1 x Satellite shifter port (per lever)
Power Source: 2 x CR1632 batteries per lever (3 to 4 years life)
Weight: Approx. 207g (Lever) + 122g to 139g (Caliper)
✅ Why This IS For You
Gravel Racers & Fast Tourers: The combination of lightning-fast wireless shifting and incredibly quiet braking lets you focus 100% on choosing the fastest line.
Flared Handlebar Fans: The lower hood body shape transitions beautifully onto wide-flared drops without creating an awkward, painful ridge under your palms.
Mud and Wet-Weather Riders: Superior hydraulic sealing, aggressive hood ribbing, and wider pad spacing mean this kit performs flawlessly when conditions turn filthy.
Tech Enthusiasts: Perfect if you want to use Shimano's Front Shift Next software to control both chainrings using just a single button on one lever.
❌ Why This May NOT Be For You
Mechanical System Lovers: If you prefer simple, cable-actuated shifting that can be fixed with basic tools in the middle of nowhere, Di2 might not be for you.
Strict Post-Mount Frames: Older gravel or cyclocross frames utilizing post-mount frame tabs will require awkward adapters to fit these modern flat-mount calipers.
Weight Weenies: While highly optimized, riders seeking ultra-minimalist setups may lean toward high-end road calipers which prioritize absolute weight savings over dirt-shedding clearance.
When installing these calipers, don't rush the centering process! Because the BR-RX820 caliper features a wider 10% pad clearance, using the traditional "squeeze the lever and tighten the bolts" method doesn't always guarantee a perfect alignment. Instead, slide a crisp business card or a dedicated metal rotor-alignment shim on both sides of the rotor before squeezing the lever and torquing the bolts down. This forces the pistons to extend perfectly symmetrically, completely eliminating trail-side rotor tick!
