Shimano GRX BR-RX820 Hydraulic Gravel Brake Caliper

Name: Shimano GRX BR-RX820 Hydraulic Gravel Brake Caliper
Brand: Shimano
SKU: BR-RX820
Price: 54.00 GBP
Availability: InStock

£54.00 GBP

Taxes included. Shipping calculated at checkout.

The Shimano GRX BR-RX820 Hydraulic Disc Brake Calliper is a compact, service-friendly gravel bike brake upgrade with a responsive bite point, excellent modulation and increased pad clearance for quieter, more predictable braking on Australian roads, gravel tracks and technical descents.

Key Shimano GRX BR-RX820 Features

• Gravel-tuned hydraulic braking with a quicker initial bite and progressive modulation
• Ten per cent more brake pad clearance to help reduce rotor rub and unwanted brake noise
• Lightweight two-piston aluminium flat mount construction
• Ice Technologies brake pad compatibility for improved heat management on long descents
• One Way Bleeding system for cleaner, more straightforward workshop servicing

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The Shimano GRX Di2 ST-RX825 combines the left and right RX825 Dual Control Levers into one premium gravel bike control package. The levers communicate wirelessly with a compatible Shimano 12-speed Di2 rear derailleur, while the front and rear derailleurs are powered by the drivetrain’s central rechargeable battery.

The left lever controls a compatible 2x Di2 front derailleur by default, while the right lever operates the 12-speed rear derailleur. Button functions can be reassigned through Shimano E-Tube Project, allowing riders to create a personalised shifting arrangement.

Product specifications

• Product type: Integrated electronic shift and hydraulic brake lever set
• Series: Shimano GRX RX825 Di2
• Included controls: Left and right Dual Control Levers
• Drivetrain format: Shimano GRX Di2 2x12-speed
• Shift communication: Wireless from levers to rear derailleur
• Brake system: Hydraulic disc brake
• Recommended brake calipers: Shimano GRX BR-RX820
• Recommended brake hose: Shimano SM-BH90-JK-SSR
• Brake hose connection: Straight
• Brake fluid: Shimano genuine mineral oil
• Servo Wave lever action: Yes
• Reach adjustment: Yes
• Free-stroke adjustment: Yes
• Funnel bleeding compatibility: Yes
• Remote switch function: Yes
• E-Tube Project firmware and function customisation: Yes
• SD300 port: One per lever
• Compatible satellite controls: Shimano SW-RS801-S, SW-RS801-T and SW-RS801-E
• Front Shift Next compatibility: Yes
• Lever batteries: Two CR1632 coin-cell batteries per lever
• Claimed lever battery life: Approximately three to four years under normal conditions
• Handlebar clamp diameter: 23.8-24.2 mm
• Colour: Shimano Series Colour, black

Wireless Shimano Di2 shifting

The Shimano GRX Di2 ST-RX825 uses wireless shift commands to reduce cockpit wiring and create a cleaner gravel bike build. Shimano’s semi-wireless architecture retains a secure central battery for the derailleurs while giving the rider cable-free electronic controls at the handlebar.

Gravel-specific ergonomics

Shimano developed the hood body around the riding positions commonly used on gravel and adventure bikes. The raised hood profile provides a secure point against which the hands can brace when riding corrugations, loose descents or broken surfaces.

The more rounded hood cross-section is designed to create a smoother transition between the lever body and a flared handlebar. This increases the available contact area and can help reduce concentrated hand pressure during long-distance gravel rides.

Textured contact surfaces

Ribbed hood rubber and an anti-slip coating on the aluminium brake levers provide dependable hand contact in dust, light rain and rough terrain. These features are especially useful when braking from the hoods on fast, uneven descents.

Servo Wave braking

Servo Wave lever action moves the brake pads towards the rotor quickly in the early part of the lever stroke, then provides greater control as braking force increases. The result is a responsive initial bite with progressive modulation, helping the rider manage traction on loose gravel or wet roads.

Adjustable fit and brake feel

Reach adjustment changes the lever’s resting position to accommodate different hand sizes and rider preferences. Free-stroke adjustment provides further control over lever travel before braking engagement.

Programmable controls

Each lever provides three Di2 buttons. In addition to conventional front and rear shifting, buttons can be configured for functions such as Front Shift Next, compatible cycle computer control or alternative shift commands.

Front Shift Next allows one chosen button to toggle the front derailleur between chainrings. This can simplify front shifting while freeing another button for a different function.

Satellite shifter integration

The SD300 connection supports Shimano SW-RS801 satellite controls. Depending on the chosen model, an additional shift button can be positioned on the tops, drops or another convenient section of the handlebar.

Lever position: Left and right
• Handlebar type: Drop handlebar
• Clamp compatibility: 23.8-24.2 mm handlebar clamping section
• Preferred application: Gravel and all-road handlebars
• Flared handlebar compatibility: Optimised for modern flared drop bars
• Reach adjustment: Individually adjustable
• Free-stroke adjustment: Individually adjustable
• Shift-button configuration: Customisable through Shimano E-Tube Project
• Brake-hose routing: Internal or external, subject to frame and handlebar compatibility

The lever bodies are intended for standard drop-bar clamping dimensions. They are not designed to clamp directly onto flat handlebars or oversized 31.8 mm handlebar centre sections.

For the best hood transition, lever position and brake access, professional installation is recommended, particularly when using internally routed handlebars or heavily flared gravel bars.

The Shimano GRX Di2 ST-RX825 Dual Control Lever Set is best suited to performance gravel riders, endurance cyclists, gravel racers and experienced bikepackers who want faster shifting with less hand movement and more control from the hoods.

Care instructions

• Wash the levers using water, mild bicycle cleaner and a soft cloth
• Do not direct a high-pressure washer at the lever pivots, hood openings, buttons or brake-hose connections
• Inspect brake hoses, fittings and lever bodies after crashes or heavy impacts
• Use only genuine Shimano mineral oil in the hydraulic brake system
• Do not allow mineral oil, chain lubricant or cleaning chemicals to contaminate brake pads or rotors
• Check lever-battery status through the appropriate Shimano system functions
• Replace batteries with the specified CR1632 type and observe correct polarity
• Replace both batteries in an individual lever at the same time
• Keep Shimano E-Tube firmware current and verify button assignments after an update
• Have the brakes bled when lever feel becomes inconsistent or whenever the hydraulic system is opened
• Follow Shimano’s prescribed clamp, hose and bleed procedures during installation
• Periodically inspect handlebar clamp security using a correctly calibrated torque wrench

Australian warranty information

Shimano Australia provides a two-year limited warranty for GRX bicycle components purchased new in Australia by the original retail purchaser, subject to its conditions and exclusions. Coverage applies to qualifying defects in materials or workmanship and operates in addition to rights provided by Australian Consumer Law.

Velo published its first-ride review of Shimano GRX Di2 RX825 on 23 May 2024 after testing the groupset over approximately 80 miles of chunky climbs, sandy descents, water crossings and singletrack. Reviewer Will Tracy praised the quality of the shifting, assured brake performance and comfort of the raised hoods during rough and extended rides. He also identified the programmable auxiliary buttons as a useful addition, particularly when configured for front shifting.

Shimano GRX Di2 ST-RX825 versus Shimano Ultegra Di2 ST-R8170

Ultegra Di2 controls are lighter and oriented towards road racing, aerodynamic road cockpits and sealed-surface performance. They are a logical choice for a dedicated road bike.

The GRX levers provide taller hoods, more pronounced surface texture, anti-slip lever treatment and a shape developed for flared gravel handlebars. They are the better choice when off-road control and secure hand placement take priority over minimum road component weight.

Shimano GRX Di2 ST-RX825 versus Shimano GRX ST-RX820 mechanical controls

GRX ST-RX820 mechanical levers provide much of Shimano’s proven gravel ergonomics without electronic shifting or coin-cell batteries. They cost less, are easier to troubleshoot in remote locations and suit riders who prefer a fully mechanical drivetrain.

The RX825 levers deliver lighter-action electronic shifts, extensive button customisation, satellite control options and a cleaner shift-cable-free cockpit. They are the more compelling option for racing, premium bike builds and riders who want consistent shifting with minimal lever effort.

Shimano GRX Di2 ST-RX825 versus SRAM Rival AXS controls

Rival AXS is often the lower-priced electronic alternative and provides simple wireless installation with access to SRAM’s modular AXS ecosystem. Its main advantages are value and straightforward wireless component pairing.

The Shimano GRX option offers more overtly gravel-specific hood details, Servo Wave brake behaviour and Shimano’s characteristic shift and brake feel. Rival may offer the more economical entry into wireless shifting, while GRX is likely to appeal to riders already invested in Shimano wheels, cassettes, brakes and workshop support.

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