By Lars Hundley
Shimano has expanded its GRX gravel component lineup with the introduction of the GRX RX825 Di2, a 2×12-speed electronic shifting system designed for gravel riders seeking reliable performance in all conditions. The new Di2 components include refined dual control levers, a Shadow RD+ equipped rear derailleur, and a gravel-optimized front derailleur.
The GRX RX825 Di2 system offers riders the benefits of Shimano’s electronic shifting technology, combined with optimized gearing options for gravel riding, racing, and all-day adventures. The redesigned Di2 system features fast, precise shifting and a wireless cockpit design, aiming to provide the ultimate performance and reliability.
Gearing Options and Compatibility The GRX RX825 Di2 components are compatible with existing RX820 cranksets, cassettes, and brakes, allowing riders to tailor their gearing to their preferences. Riders can choose between 48/31-tooth or 46/30-tooth chainrings, paired with either an 11-36T or 11-34T cassette, offering a wide gear range with tight gear steps for comfortable cadence.
Shimano’s latest carbon gravel wheels, the WH-RX880, feature a 25mm internal width and an updated Direct Engagement freehub, providing a vital connection between rider and road.
Wireless Cockpit and Ergonomic Enhancements
The GRX Di2 system features a wireless, gravel-specific cockpit with raised hoods and ribbed surface texture for enhanced hand security. The dual control levers employ a gravel-optimized body shape cross-section for seamless integration with flared handlebars, creating a smoother transfer from handlebar to hood and eliminating pressure points.
The levers also feature a third Di2 button on the inside of the hood, which can be used for shifting or scrolling through screens on a cycle computer. Additionally, accessory shift buttons can be plugged in at various locations, allowing riders to maintain their effort without moving their hands.
Shadow RD+ Rear Derailleur and Wider Chainline The RX825 rear derailleur incorporates Shimano’s Shadow RD+ technology, offering a convenient on/off switch for easy wheel removal and additional drivetrain tension for quieter rides and more precise shifting. The rear derailleur also serves as the communication hub of the drivetrain, with integrated D-Fly connectivity and charging.
The RX825 system employs a wider, +2.5mm chainline compared to conventional road front derailleurs, improving tire clearance to accommodate wider tires and muddy conditions.
Customization and Front Shift Next Using Shimano’s E-Tube Project Cyclist application, riders can customize various aspects of their Di2 system, including gear shift intervals, button assignments, automatic shift modes, and fine-tuning shifting.
Shimano has also introduced Front Shift Next functionality, which allows users to program any 12-speed Di2 button to shift the front derailleur to the opposite chainring and toggle back and forth using the same button. This new firmware is compatible with GRX RX825 Di2 and Shimano’s family of 12-speed road Di2 groups, simplifying the gear-changing process and freeing up switches for other tasks.
- Shimano Shadow RD+ Chain Stabilization
- Integrated D-FLY connectivity and charging
- 12-speed
- Compatible with 11-34T and 11-36T cassettes
- Weight: 310 grams
- Chainline +2.5mm vs. conventional road front derailleur
- Wider tire clearance
- 2 x 12-speed
- Weight: 142 grams
ST-RX825 – Hydraulic Disc Brake Dual Control Lever
- Wireless Di2 Connectivity
- 2 x 12-speed dual control lever
- Gravel-specific brake lever and bracket ergonomics
- New flared drop bar optimization
- Anti-slip coating on brake lever surface
- Three Di2 buttons per lever for E-tube Project Cyclist app customization
- Replaceable coin cell batteries (2 x CR1632) with expected lifespan of 3.5 to 4 years
- Weight: 415 grams / pair