Shimano GRX 12-speed goes electronic with 2x12-speed Di2 shifting

Shimano has officially unveiled electronic shifting for its 12-speed GRX groupset, seeing it draw level with SRAM and Campagnolo equivalents.

Named RX825, the new electronic components work in tandem with the previously launched mechanical GRX RX820 groupset components to form a complete electronic groupset. 

The move comes less than a year after Shimano released its 12-speed mechanical offering, in August 2023, claiming that "about 75% of the gravel market is mechanical". At the time, Road Brand Manager Nick Legan told us "we wanted to focus on the bulk of the market first."

Although 12-speed GRX now has a Di2 option, it’s limited to the 2x12-speed ‘Undroppable’ option, while the two 1x12-speed configurations remain mechanical-only – for now.  

Shimano has also added a new front-shifting mode. Called Front Shift Next, it allows the rider to program one button to initiate a front shift from the chainring currently in use to the second ring and is also being rolled out as a firmware update to 12-speed Di2 road groupsets.

Works with mechanical GRX 2x12-speed components 

The 2x12-speed Di2 groupset works with the same chain, cassette, crankset and brake calipers as used by mechanical GRX 2x12-speed. It’s a similar arrangement to how 2x11-speed electronic GRX is built up, with only the shifters and derailleurs along with the central Di2 battery and wiring differing between electronic and mechanical options. 

That allows you to choose between a range of parts to build your bike’s groupset. So GRX RX825 can be used with either the GRX RX820 48/31t crankset or the RX610 46/30t option. At the rear, the electronic derailleur is compatible with either an 11-34t Dura-Ace, Ultegra or 105 cassette or the non-series HG710 11-36t cassette, so there’s a reasonable choice of configurations that provides up to 506 percent gear range and ratios well below 1:1.

The GRX Di2 drivetrain uses the same Hyperglide+ cassette tooth and chain profile as the 12-speed road groupsets (and 12-speed MTB groupsets), which is claimed to increase shifting speed by 58 percent at the rear and 45 percent at the front relative to standard Hyperglide.

Shimano has ported to GRX RX825 Di2 the wireless connection between the shifters and derailleurs found in its 12-speed Di2 road groupsets, Dura-Ace, Ultegra and 105 Di2. As with those groupsets, the derailleurs use a single internal battery to power them and the rear mech houses the charge port, pairing/adjustment/battery-check button and Wi-Fi connectivity to the E-Tube Project phone app for groupset configuration and firmware updates.

The GRX RX825 shift levers have a similar profile and ribbed hoods to mechanical GRX 12-speed and are designed for hand comfort on the flared bars typical of gravel bikes. The levers also feature the same anti-slip surface using a plastic coating borrowed from Shimano’s fishing rods.

There are hidden third control buttons that can be configured using the E-Tube Project app and you can wire in satellite shifters to allow you to shift from the drops, the tops or bar extensions, in addition to the levers.

Gravel riders have actually stolen a march on mountain bikers, as the MTB-specific XTR Di2 is only available as 2x11-speed at present, again with no 1x Di2 option.

Ride an e-MTB, however, and you can choose a 1x12-speed Di2 set-up for Deore XT, powered by the e-MTB’s main battery, so Shimano clearly has the tech know-how to make 1x12-speed work.

New Front Shift Next function 

There’s a new function called Front Shift Next rolled out with GRX RX825, which you can program via the E-Tube Project app to work using any Di2 button. Press the button and the front mech will shift between chainrings, either up or down depending on which ring it’s on at the time. 

It’s similar to the front shifting logic used by SRAM in its AXS groupsets, but controlled via one button rather than SRAM’s method where two buttons are pressed simultaneously.

Using Front Shift Next frees up a shift button to use for something else, so you can program it, for example, to switch on lights or scroll through screens on a cycling computer. Shimano is rolling out the same functionality to its 12-speed road bike electronic groupsets via a firmware upgrade.

GRX Di2 2x12-speed pricing 

The GRX Di2 right and left shifters with brake calipers are priced at $556.99/£399.99 each. The rear mech costs $409.99/£324.99 and the front mech $209.99/£184.99. 

Paired with the previously released GRX 2x12-speed parts including the crankset and a Di2 battery, this puts the price of a complete groupset at around $2,533/£2,100.

That’s close to $1,000/£900 more than mechanical GRX RX820 2x12-speed but comparable to GRX RX815 Di2 2x11-speed. Both those groupsets are available with a hefty discount though, if you shop around, so you can probably expect the same in future with 12-speed GRX Di2.

Wait, there’s more! New GRX branded pedals 

Launched as a limited edition, the double-sided GRX SPD M8100-UG pedals look suspiciously like Deore XTs. That’s because that’s what they are, just with GRX United in Gravel graphics, which Shimano says makes them more fun.

Shimano claims a weight of 342g for a pair, which come with the usual SPD characteristics of adjustable release tension, low stack height, wide platform and offset binding to help shed mud.

Shimano isn’t the first brand to launch a gravel bike version of its pedals. Look has a gravel edition of its X-Track SPD-compatible pedals. Originally launched as a limited edition of 2,000 sets in 2019, the X-Track Gravel pedals are anodised brown rather than black and are still in Look’s catalogue, so clearly there’s a market for gravel-branded SPD gravel bike pedals.

The Shimano pedals’ graphics extend to the top wear surfaces and the sides of the pedals, so it’s an open question how well they’ll withstand clipping in and out and general off-road wear and tear. 

The GRX limited edition pedals are priced at $138/£114.99 a pair.