2x12-speed Shimano GRX Di2: Shimano presents electronic 12-speed gravel groupset

The GRX from Shimano is a well-known gravel groupset. Until now, electronic versions were only available for 11-speed drivetrains, although Shimano launched a 12-speed GRX on the market last year. Now there is also a Di2 version: the Shimano GRX Di2 2x12-speed groupset. This new electronic gravel groupset is designed to offer even more comfort and control.

The Dual Control shift/brake levers are designed to improve comfort and controllability, the Shadow RD+ rear derailleur ensures reliable chain management and the front derailleur specially optimised for gravel enables precise changes between the large and small chainrings.

2x12-speed GRX Di2 e-gear: New member of Shimano's gravel family

We haven't ridden the new GRX yet, but will be testing it extensively soon.

It was only a matter of time, and now the time has come: Shimano is expanding its gravel family with the electronic version of the 2x12-speed GRX. The new electronic shift/brake levers, the satellite shifter, the front derailleur and the rear derailleur of the GRX RX825 are combined with the existing cranks, cassettes and brakes of the GRX RX820. Shimano promises "legendary shifting performance and reliability". Another advantage is that the components of the GRX RX825 are compatible with other GRX variants. This means that anyone can put together their preferred gear ratio. The RX820 crank with 48/31 teeth can be combined with either a cassette with 11-36 teeth or with 11-34.

Compatible gear ratios of the Shimano GRX RX825 Di2

• 48/31T RX820 crank
• 11-36T HG710 cassette
• 11-34T R9200, R8100, R7100 cassettes

Gravel now gets Di2 shifting technology

Shimano remains true to tradition with its electronic groupsets and continues to rely on cable connections to ensure a stable and reliable power supply for the rear derailleur and front derailleur. These components are powered by a central battery that is connected to them via thin cables. This system prevents different charging states of individual components. In contrast, SRAM uses separate batteries for the rear derailleur and front derailleur. Both manufacturers, SRAM and the newer Shimano Di2 groupsets, have batteries in the shifters.

Wireless cockpit with Shimano's Di2

The brake/shift levers of the 12-speed GRX Di2 are adapted to gravel requirements. This is ensured by:

• raised croissant with a
• ribbed surface texture and
• anti-slip brake levers.

As with the previous models of the Di2 shift/brake levers in the GRX RX815 series, the new Dual Control levers also feature a third Di2 shift button on the inside of the croissants. This makes it possible to control additional functions without having to let go of the secure grip on the handlebars.

The button can be used to perform various actions: It can be used as an additional control for the shifting system or to conveniently scroll through the pages of a compatible bike computer.

Ideal for gravel handlebars with flare

Shimano has designed the 2x12-speed GRX shift/brake levers to fit seamlessly into a modern gravel cockpit with flared handlebars. The slightly rounded shape ensures a smooth transition from the handlebars to the STI horns and increases the gripping surface. This should reduce the risk of pressure points.

ST-RX825: Dual Control shift/brake lever for hydraulic disc brakes

• Wireless Di2 connectivity
• 2 x 12-speed Dual Control levers
• Gravel-specific, ergonomic brake levers
• Optimised for flared handlebars
• Anti-slip coating on the brake lever surface
• Three Di2 buttons per lever, individually configurable via the E-TUBE PROJECT Cyclist app
• Replaceable button cells (2 x CR1632) with an expected service life of three and a half to four years
• Weight: 415 g / pair

Additional switches for all grip positions on the Di2

The GRX-Di2 system from Shimano allows additional shifters to be added. This can be particularly useful to increase comfort and efficiency when riding. For example, many riders use aero handlebar attachments on long distances. Additional switches can be fitted here to enable gear changes in the trailer position. If you often ride on the top bar or in the drops, you can also install additional controls there to change gears without changing your hand position. Other functions can also be assigned to these switches via the E-Tube Project Cyclist app, such as operating a compatible bike computer or counting laps during interval training.

Shimano Shadow RD+ rear derailleur

The RX825 rear derailleur from Shimano is equipped with the Shadow RD+ "Clutch" mechanism, which fixes the rear derailleur cage and thus prevents chain slap and noise. This also reduces the risk of the chain jumping off. The mechanism can be deactivated with a simple lever movement to make it easier to install and remove the rear wheel.

Another feature of the Shimano 12-speed Di2 road bike groupsets is that the rear derailleur serves as the communication centre for the entire system. This is also the case with the 2x12-speed GRX Di2. The rear derailleur communicates wirelessly with shifters, compatible third-party devices and the E-Tube Project Cyclist app on the smartphone. The charging port for the battery is also located on the rear derailleur. The multifunction button can be used to check the charge status, establish a Bluetooth connection or activate the adjustment mode for the rear derailleur and front derailleur.

RD-RX825 rear derailleur in detail

• Shimano Shadow RD+ chain stabilisation
• Integrated D-Fly connectivity and charging port
• 12-fold
• Compatible with 11-34T and 11-36T cassettes
• Weight: 310 g

Wider chain line for more clearance

On the RX825, as on the first GRX series, the chain line is offset outwards by 2.5 millimetres. This creates additional space for wider tyres or for mud that accumulates on the tyres.

FD-RX825 front derailleur in brief

• Chain line offset outwards by 2.5 mm compared to road bike derailleurs
• Allows wider tyres
• 2 x 12-fold
• Weight: 142 g

App configuration for individual customisation

Shimano's E-Tube Project Cyclist app can be used to adjust shifting intervals in Multi-Shift mode as well as the assignment of functions to individual shift buttons and the parameters for Synchronised and Semi-Synchronised Shift. These adjustments make it possible to adapt the shifting system to individual preferences, riding styles or areas of use.

New: Front Shift Next

The Front Shift Next function is being introduced at the same time as the RX825. What is behind this term? Front Shift Next enables shifting at the front derailleur and will be available in the future via a firmware update. With the E-Tube Project Cyclist app, any Di2 buttons on all 2x12-speed systems can be programmed to control shifting between the two chainrings on the front derailleur. If the chain is on the large chainring, the button switches to the small chainring and vice versa. This should lead to faster and more intuitive shifting processes and offer the option of assigning a different function to the button on the STI that becomes free.