2x12-speed Shimano GRX Di2: Electronic 12-speed gravel groupset from Shimano is here

Shimano has had a special gravel groupset, the GRX, since 2019. Electronic variants were previously only available for 11-speed drivetrains, although last year the Japanese component manufacturer launched a 12x GRX on the market has brought. It was only a matter of time before there was a Di2 version. And now it's here, the Shimano GRX Di2 2x12-speed groupset. In terms of comfort and control, the new electronic gravel groupset is set to go one better.

The Dual Control shift/brake levers are designed to optimise comfort and controllability, the Shadow RD+ rear derailleur ensures reliable chain management and the gravel-optimised front derailleur enables precise changes from the large to the small chainring and vice versa.

2x12-speed GRX Di2: Shimano's gravel family grows

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

It was a matter of time and now it's here. Shimano is expanding its gravel family with the electronic version of the 2x12-speed GRX. The new electronic shift/brake levers, the matching satellite shifter as well as the front derailleur and rear derailleur of the GRX RX825 are combined with existing cranks, cassettes and brakes of the GRX RX820. Shimano promises "legendary shifting performance and reliability". What is practical is that the components of the GRX RX825 can be mixed with other GRX variants. This means that everyone 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

Di2 shifting technology for gravel

As always, Shimano relies on cable connections for its electronic groupsets to guarantee a stable, safe and long-lasting power supply to the rear derailleur and front derailleur - supplied by a central battery. In the new 2x12-speed GRX Di2, too, thin cables transmit the power from the battery to the rear derailleur and front derailleur. Thanks to this centralised power supply, there are no different charge levels for individual components. SRAM groupsets have one battery on the rear derailleur and one on the front derailleur. Both SRAM and newer Shimano Di2 groupsets have batteries in the shifters.

Cockpit without cables

The brake/shift levers of the 12-speed GRX Di2 are designed specifically for gravel. This is ensured by:

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

As with the predecessor models, the Di2 shift/brake levers of the GRX RX815 series, the third Di2 shift button on the inside of the croissants on the new Dual Control levers ensures that the hand does not have to leave the secure grip on the handlebars to control additional functions.

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

For gravel handlebars with flare

The 2x12-speed GRX shift/brake levers were designed by Shimano so that they can be integrated into a modern gravel cockpit with flared handlebars. The slightly rounded shape makes the transition from the handlebars to the STI horns seamless 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

Di2 switch possible for all grip positions

Additional switches can be added to the GRX-Di2 system. Why might this be useful? For example, many people use aero handlebar attachments on long journeys. Additional switches can be added to enable shifting in the trailer position. If you ride a lot on the top handlebars - or in the drops - you can also attach additional controls here to be able to shift back and forth between gears without changing position. Other functions can be assigned to the shifters via the E-Tube Project Cyclist app: How about operating a compatible bike computer or a lap counter during interval training sessions, for example?

Shimano Shadow RD+ rear derailleur

The RX825 rear derailleur is equipped with Shimano's Shadow RD+ with the "Clutch" mechanism. When switched on, this mechanism fixes the rear derailleur cage in place, which in turn prevents the chain from hitting the cage with the corresponding noise and the risk of the chain jumping off. The mechanism can be switched off with a simple lever movement, e.g. for fitting and removing the rear wheel.

A feature of Shimano 12-speed Di2 road bike groupsets is that the rear derailleur acts as the communication centre for the system. This is now also the case with the 2x12-speed GRX Di2. The rear derailleur communicates wirelessly with shifters, compatible devices from third-party manufacturers 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 leaves more room for wider tyres - or for mud that sticks to 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

Configuration via app possible

With the E-Tube Project Cyclist app from Shimano, the shifting intervals in Multi-Shift mode, the assignment of functions to individual shift buttons and the parameters for Synchronised and Semi-Synchronised Shift can be adjusted and adapted to individual preferences, riding style or area of use.

New: Front Shift Next

Front Shift Next makes its debut at the same time as the RX825 is unveiled. Front Shift ... what? It's a function for shifting gears on the front derailleur. The new function will be available in future via a firmware update. In future, the E-Tube Project Cyclist app will allow any Di2 button on all 2x12-speed systems to be assigned the function of changing to the second chainring on the front derailleur. If the chain is on the large chainring, the button switches to the small chainring; if it is on the small chainring, the same button switches to the large chainring. The result should be faster, more intuitive shifting processes and the option of assigning any other function to the button on the STI that becomes "free" as a result.