Adventure Cycling Association

Today Shimano unveiled the latest version of its mechanical GRX gravel-focused drivetrain, now with 12 cogs on the cassette instead of 11. But Shimano didn’t just slap on an extra gear and call it a day; instead, they went for a top-to-bottom refresh, with updated brake-shift levers for added comfort and control, redesigned brake rotors for better stopping, and a new set of wheels with updated hubs and carbon rims.

Shimano has also split its GRX offerings into three categories: Unbeatable, Unstoppable, and Undroppable. 

Unbeatable is aimed at the gravel race crowd who want the simplicity of a 1x system and the tighter cog spacing of a smaller cassette to more easily achieve their desired pedaling cadence. The GRX820 1x crankset is available with a 40T or 42T chainring and mates to a 10–45T cassette, using a medium-cage clutch derailer. 

Unstoppable is a also 1x system but with a bigger cassette, aimed at those who want the broadest gear range possible. Again, riders can pick from a 40T or 42T chainring for their GRX820 crank but they’ll have a 10–51T cassette with a long-cage clutch derailer. 

And Undroppable is the new 2x drivetrain for riders who prefer something more traditional. Like the previous version of GRX, the 2x crankset has 48/31T chainrings, but now there’s an 11–36T cassette in addition to the 11–34T. 

Those are the top-level offerings, but Shimano didn’t forget about the more budget-minded riders. The new 12-speed tech has trickled down to the 600 level in the new GRX610, including updated brake-shift levers with the same ribbed texture on the hoods and anti-slip coating on the levers as the GRX820 models, and new 12-speed cranksets, including the familiar 46/30T chainrings for the double and 1x cranks available with either 40T or 38T chainrings. 

The new RX880 wheels feature 32mm deep carbon rims with a 25mm internal width and 24 J-bend spokes laced to hubs with Shimano’s Direct Engagement freehub mechanism and its tried-and-true cup-and-cone bearings. In a first for Shimano, the freehub bodies are replaceable, so you can swap between the two new options. 

Yes, you’ll need a new freehub body if you want the 12-speed GRX on your bike. The 1x options use Micro Spline, the current standard for Shimano’s 12-speed MTB drivetrains. It’s the same freehub body but on a shorter, 142mm wide hub for modern gravel bikes. The 2x options use the new HG L2 freehub body, which is Shimano’s new 12-speed-specific road offering.

Use a dropper post on your gravel bike? You’ll be happy to hear that Shimano continues to offer a 1x version of the left brake-shift lever designed to actuate a dropper. 

You might be thinking to yourself, “That’s all well and good, but how does it ride?” I can report that it works pretty darn well. I joined a cadre of other bike editors for a few days in Bend, Oregon, earlier this month to get an early preview of the new GRX, ride some dusty roads and trails, and eat some good food. 

Shimano outfitted me with a Litespeed Ultimate G2, a titanium gravel bike with a carbon fork, set up with the Unstoppable 1x group with a 40T chainring and the 10–51T cassette, as well as the new carbon wheels, GRX hydraulic disc brakes, and Pro bits for the saddle, seatpost, and cockpit. 

Under hazy skies, we set off for a 40-mile ride on local paved bike paths, smooth and twisty singletrack, and gravel roads with a dose of washboard. It was hot and dry and very, very dusty. It was a fun ride with good people, and it provided a great opportunity to put the new 12-speed GRX through its paces. 

I had no complaints about the performance of the previous GRX, so I wasn’t shocked when I got nothing but strong, reliable braking and quick, clean shifting from the new bits. The updates to the brake hoods added a dose of comfort and control, and in the drops the levers felt like they were in the perfect position — I never had to reach for them. The carbon wheels spun up quickly, as expected, but as for qualities like stiffness and damping, it was hard to parse that out considering it was one ride on a new-to-me bike. 

The only complaint I had about the previous iteration of GRX was the lack of gearing range for the 1x versions. In the new 12-speed Unstoppable, I have no such qualms. With a lightweight bike and a 40T chainring shifting across the 10–51T cassette, I had all the gears I could have asked for. The shift action was light and the lever throw was pretty moderate considering the big cog jumps. Shifting under load was smooth and noise-free, thanks to the Hyperglide+ shift ramps.

We had planned for a second day of riding, but the local wildfires had other ideas: we got smoked out and instead spent the morning visiting Abbey Tools and Robert Axle Project/Old Man Mountain, both located right in Bend. 

While my first impressions were good, one ride isn’t enough for a full review. Luckily, Shimano was kind enough to send me a group for long-term testing, so keep an eye out for a full review in the future.

For more details about the new 12-speed GRX, click here.