Cycling News

First Look: the new Shimano GRX Di2 12-speed gravel groupset

Shimano GRX Di2

The new Shimano GRX Di2 gravel groupset is here. When Shimano updated its gravel-specific sets to 12-speed in August 2023, the company actually launched not one, but three groups. A 2-by option, and two 1-by options with different gear ratios and rear derailleur cages. But Di2 was not among them, a conspicuous absence from the company that first made electronic shifting for bikes viable. With even Shimano admitting at the time that Di2 was in the works, it was only a matter of when, not if, the 12-speed electronic set would make a debut.

This latest GRX Di2 is very much an evolution rather than revolution, building on both the previous 11-speed generation of GRX, and the current 12-speed road groups. This latest update brings much of the function and feel of Shimano’s road Di2 groupsets to GRX, adapted with gravel-specific features.

Shimano GRX Di2 gains parity with road groups

The most obvious change to GRX Di2 that is it is now 12-speed. More important than an extra cog though, is that it brings with it a slightly wider range 11-36 cassette. Where previously Shimano’s 2-by GRX setup only went up to 34, the new cassette offers slightly lower gearing. However, given Shimano’s notoriously conservative officially approved specifications, there is a good chance it will work fine with slightly bigger cassettes for even lower gearing. It is still paired with your choice of either 48/31-tooth chain rings up front, or a 46/30-tooth for extra-low gearing.

The entire Di2 setup has also been updated, consistent with Dura-Ace, Ultegra and 105 Di2. The new shifters are wireless, powered by two coin cell batteries in each shifter, but the two derailleurs are still connected to a central battery. Shimano maintains that this arrangement gives the benefit of a wireless cockpit, with minimal fishing of wires, while maintaining longer battery life.

This arrangement also means that much of the 12-speed road groupset components and GRX components are largely interchangeable. If you prefer the shape and feel of the road Di2 shifters, and want to use them on your GRX Di2 gravel bike, you can. Or if  you want to run GRX’s clutch rear derailleur on your Ultegra Di2 equipped road bike, you can do that, too. The only caveat is that the crankset and front derailleur must be paired within the same family, owing to chainline differences between GRX and the road groups.

Image: Nick Iwanyshyn

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