Shimano 12-speed GRX Di2 long-term review: 2x shifting for off-road riding isn’t dead after all

It had been a while since I last rode a 2x setup anywhere but on the road. Coming from a cyclocross background, I was an early adopter of the 1x logic that SRAM introduced to the ‘road’ category with its CX Force 1 groupset in 2014. The improved chain retention, reduced mechanical complexity, and lighter overall weight made sense for off-road riding. And, when gravel riding gained popularity, I never even considered running a 2x setup on my gravel bikes, convinced that less was more—especially in the muddy and wet conditions I typically ride in. It was an easy choice, too, as SRAM has all but phased out 2x cranksets in its off-road lineup, and Campagnolo embraced 1x with its Ekar groupsets as well. Shimano, however, has taken a different approach: while its 12-speed mechanical GRX groupset offers a 1x option, the electronic Di2 version remains staunchly 2x-only. At first, it was easy to dismiss Di2 for that limitation—but lo and behold, not only did I not mind relearning to use a front derailleur, I’ve actually come to appreciate it.

I’ve been riding the Shimano GRX Di2 RX825 groupset for the past eight months or so, and while there certainly are some drawbacks to the groupset, I’m surprised to find that I’m in no hurry to revert back to a 1x.

Meet the Shimano GRX Di2 RX825 groupset

Following the release of its mechanical 12-speed GRX groupset in 2023, Shimano introduced an electronic version in 2024, bringing its gravel lineup closer to competitors SRAM and Campagnolo—both of which are now offering 13-speed gravel drivetrains.

Shimano has offered 12-speed electronic road groupsets—Dura-Ace R9200 and Ultegra R8100—since 2021, so the know-how had been there all along. But the delay was intentional, the reason being market demand.

"We feel pretty strongly that about 75% of the gravel market is mechanical. That's what they're purchasing," Shimano's Road Brand Manager, Nick Legan said. "We love electronic groupsets. We helped pioneer them. We have some pretty amazing ones, but we wanted to focus on the bulk of the market first."

What’s new:

The electronic RX825 components work in tandem with the previously launched mechanical GRX RX820 components to form a complete electronic groupset. The crankset, brake callipers, cassettes and chain are all carried over from the RX820 mechanical gruppo, with only the derailleurs and brake-shift levers being new. Of course, the Di2 version also has different wiring and a central Di2 battery.

The wireless connection between the shifters and derailleurs is the same as Shimano’s 12-speed Di2 road groupsets in that both derailleurs use a single internal battery to power them while the shifters are powered by two CR1632 coin cell batteries. The rear derailleur houses the charging port, pairing button and Wi-Fi connectivity to the E-Tube companion app.

And, carried over from the Ultegra R8170 Di2 road shifters, the new GRX shifters now feature the popular bonus button. This extra button is located on the inside of the hood to be operated with one’s thumbs. The button can be customised through the companion app to control various functions, such as shifting or toggling through the pages of one’s cycling computer.

With the groupset, Shimano also introduced a new front-shifting mode called “Front Shift Next.” When enabled, this allows the rider to use a single button to initiate a front shift from the chainring, away from the one it’s currently in i.e. shift into the big ring when it’s in the small ring and vice versa.

Installation

Whenever possible, I prefer to install new groupsets myself instead of leaving it to my trusty mechanic. This approach allows me to gain an intimate understanding of the new products before even taking the bike out for a ride.

Despite the frequent use of the word “wireless” in descriptions for any Di2 product, let’s be clear: Shimano’s groupsets are not truly wireless. While the wireless communication between the shifters and derailleurs is a significant improvement over previous models, you’ll still end up fiddling with battery wires.

In this setup, the front and rear derailleurs are connected to a central battery located in the seatpost. While it’s not overly cumbersome, it does require internal cable routing, and having to forego my Ergon leaf suspension seatpost in favour of a rounded seatpost to accommodate the battery.

Shimano claims that the “new GRX Di2 is wired where it makes sense,” claiming that the wired connections to the battery provide “stable, long-lasting power” to both derailleurs.

I’ve never had issues with SRAM’s derailleur batteries —instability or otherwise— but Shimano’s central battery does indeed seem to offer a longer runtime.

The installation still isn’t as quick and easy as its SRAM counterparts, but if you’re a patient and halfway decent tinkerer, the process is fairly quick.

I found that I’m more patient with the hands-on part of the installation than the electronic part. Pairing everything is straightforward but it may take a few tries – especially when trying to capture the tiny QR codes on the shift paddles in garage lighting. I ultimately had to break out a headlamp and try various angles before succeeding. But once all the parts are scanned, any subsequent connecting with the master unit —the rear mech—is a breeze.

The app allows for complete customization of the function of each paddle or button on the shifters, including the new bonus button.

Gearing

As mentioned above, the electronic components are compatible with the previously released 12-speed mechanical components. This cross-groupset compatibility gives users some flexibility in both the gear range and price of their build. For instance, the GRX RX825 can be used with either the GRX RX820 48/31t ($249) crankset or the RX610 46/30t ($159) option. In the rear, riders can opt for an 11-34T ($65-$359) or 11-36T cassette ($88) for tighter gear steps. The biggest gear range here is a generous 506 percent with ratios well below 1:1.

My review setup consisted of the RX820 crankset with 48/31 chainrings up front and an 11-36T HG710 cassette in the rear. Once I remembered to use my front derailleur, I found the gear range to be generous—certainly enough to get me to the top of even the steepest and loosest gravel climbs in my area.

What’s more, I had forgotten how nice those tight gear steps can feel. With a 1x setup, there’s often a moment when a gear feels ever so slightly too big or too small. But with 2x gearing, I felt more in control of my cadence, allowing me to fine-tune my effort rather than adapt to whatever ratio was available. This ultimately can lead to less grinding or, conversely, spinning out. You know that moment when you’ve maxed out your gearing but you hit your shift paddle anyway, hoping an extra gear will magically materialise? Yeah, well, there’s been a lot less of that.

As much as I like the 1x setup for practical reasons, I can’t deny that a 2x system does yield smoother pedalling.

Shifting

The GRX RX825 brake-shift levers look and feel similar to the mechanical version — and that’s a good thing.

The ergonomics were designed with flared bars in mind, and they are very good. In fact, these shifters are the most comfortable Shimano shifters I’ve used and second on the market only to SRAM’s latest Red AXS brake-shift levers.

More than just comfort, the RX825 levers inspire confidence on technical terrain, especially when paired with flared bars. I don’t ride in the drops very often, and the hood shape of these RX825 shifters almost hooks the hand in place. Even on wet days, the hands feel secure.

The shift paddles and auxiliary buttons are easy to access, and that extra set of buttons is very useful. It’s no surprise that SRAM quickly followed suit, adding a similar feature to its latest Red AXS release. While I find SRAM’s bonus buttons easier to reach, I prefer the slightly larger button size Shimano uses.

One good use for this button is the new “Front Shift Next” function explained above. A quick press toggles the chain between the front chainrings, which can be handy when you’re approaching a steep climb, want to rail a descent or need to respond quickly to a move in the peloton. It does raise a question: with a single button capable of handling front shifts, do we even need a two-button system for the front derailleur anymore?

The front derailleur differs from Shimano’s road offerings in that it’s positioned 2.5mm further outward, allowing for more mud and tyre clearance. It’s also optimised for the smaller chainrings.

The rear derailleur sports the so-called Shadow+ chain stabilising system – a clutch system taken from the mountain bike world. Engaged using a small lever on the outside of the mech, the clutch adds a touch more tension to the drivetrain for a quieter ride and more precise shifting.

Any communication between the shifters and derailleurs is nearly instant. And the resulting shifts are crisp, smooth and reliable. Indexed once, you never have to think about it again. There’s no faulting it.

Braking

The GRX RX820 brake callipers were carried over from the mechanical groupset. These sport Shimano’s Servo Wave technology, which provides a 10% wider path clearance for improved rotor path and reduced brake noise.

The system is best paired with the latest CL rotors, which were first seen on the Shimano 105 Di2 R7100 groupset. These rotors are built around an aluminium carrier, said to reduce heat deformation and maintain consistent braking performance.

Out on the various gravel paths and singletrack trails, braking is reliable, powerful and noticeably quieter than its competitors. I’ve also been impressed with the slow wear and durability of both the brake pads and rotors.

The quest for rattle-free shifters

A few months into riding this groupset, I began noticing a rattle coming from the brake-shift levers. What started as a little bit of rattling soon became a constant, noisy distraction that was definitely coming from the shifter bodies.

In past Di2 shifters, the reach and free stroke adjustment screws were known culprits of rattling so I peeled back the rubber hoods and checked and tightened every screw. No change. Perplexed, I took it to my trusted mechanic, who completed the same process but had no luck either. He called Shimano and they were quick to replace the levers.

However, 20 miles into a ride with the new levers, the rattling started up again. Groan. So Shimano sent me yet another set of shifters, along with an apology this time. Turns out: I hadn’t been the only unlucky user, and adjustments had been made.

“Shimano is constantly evaluating the performance of our products. Based on valuable rider feedback an update has been made to the GRX ST-RX825 lever to improve the long-term user experience,” the brand stated.

The brand remains vague on exactly what changes were made to eliminate the rattling but I’ve enjoyed several hundred rattle-free miles since.

Funnily enough, however, my now third set of shifters have a different but minor defect: in the E-Tube app, the left shifter registers as the right and vice versa. It’s presents no issue in day-to-day riding but I did have some head-scratching moments when customising the button functions.

Should you too encounter any issues with your RX825 shifter, bring your bike to a Shimano dealer for help.

The unsung heroes

With the release of its 12-speed GRX groupsets, Shimano also took the opportunity to refresh its carbon gravel wheelset. The WH-RX880 wheels feature 25mm internal, tubeless-compatible but hooked rims, and offer the same direct engagement hub system as found on the latest Dura-Ace wheels. With minimally branded matte black rims, the wheels are understated and, in my opinion, under-marketed.

Sure, the 32mm rim height doesn’t have much to offer in the way of aerodynamics, but the wheels have been absolutely bombproof. I started riding these with the release of the mechanical groupset in 2023 and they’re a bit of an unsung hero of this 12-speed GRX release.

They’ve been easy to set up and have deftly handled everything I’ve thrown at them with ease. They’re responsive yet not too stiff and at just a hair under 1400 grams, they’re reasonably lightweight. At $1,550 retail, they’re a decent value, too.

Likewise, I’ve very much enjoyed the Pro Discover Carbon Handlebar. Made with the GRX Di2 groupsets in mind, the bars sport a shallow 105mm drop, a short reach and a 20-degree flare. This flare brings out the best of the RX825 shifters’ ergonomics, offering a confident grip for control across the rougher, more technical terrain.

Sometimes, the best gear is the kind you don’t have to think about—it just works. These two components fall squarely into that category.

Price

The shifters and brake callipers are priced at $556.99/£399.99 each. The rear derailleur costs $409.99/£324.99 and the front mech $209.99/£184.99. Paired with the previously released GRX 2x12-speed components and a Di2 battery, this puts the cost of a complete groupset, as reviewed here, at around $2,535 / £2,100. That’s nearly a grand more than the mechanical version but in reality, those two setups offer very different riding experiences.

A more fitting comparison would be SRAM’s Force AXS Wide 2x setup, a similarly weighted, fully wireless groupset designed for gravel with a 43/30T chainring combo and a 10-36T cassette. Notably, it includes a power meter, which Shimano’s offering doesn’t, and yet it comes in cheaper at $2,201 / £1,859. However, many Shimano loyalists will be quick to argue that there might be a reason SRAM has leaned so heavily into 1x for off-road riding—its front shifting has never matched Shimano’s speed or precision.

Verdict

The Shimano GRX Di2 RX825 surprised me in ways I didn’t expect. After years of riding 1x setups and fully embracing the simplicity they offer, I never imagined I’d using a front derailleur for off-road riding again—yet here I am, fully appreciating the tighter gear steps that 2x provides. The shifting is crisp and effortless, the ergonomics are some of the best I’ve felt, and the braking performance is as solid and reliable as ever.

Yet there’s nothing flashy or widely exciting to write about either. The aesthetics are bland and there’s little innovation. When it comes to gravel, I can’t help but feel like Shimano continues to play catch-up rather than lead.

Shimano is playing it safe yet it does so with a level of refinement that’s hard to ignore. It may not be the sexiest groupset out there but it’s polished and well-executed.