Shimano GRX 12-Speed: Getting Rolling

Shimano GRX Press Camp
Image: Shimano

Shimano GRX 12-Speed: Getting Rolling

For the launch of its second-generation GRX groupset, Shimano has focused on evolution, and on giving riders more choices. They didn’t need a revolution, as the existing 11-speed groupset was, and is, excellent in almost every way. That said, since the industry has moved to 12-speed, and in some cases, 13-speed components, I’m sure Shimano knew it was time to give GRX the update it needed.

Shimano Press Camp
Even on the better of our two days of riding, you could still easily see the wildfire smoke in the air. Image: Shimano

We covered the technical details of the new GRX groupset here and here, so be sure to check those out. My review will focus on the “Unbeatable” version of new GRX, which is a 1×12-speed setup using a 40t chainring up front (42t is also an option) and a 10-45t Deore XT cassette in the rear. While pitched at competitive, or fast riders, which I’m really not anymore, the setup appeals to me due to the smaller gaps between gears compared to the “Unstoppable” setup, which uses a wider 10-51t cassette.

Even though it provides even tighter spacing between gears than the setup I chose, I didn’t go with the 2×12-speed “Undroppable” setup because I also wanted to run a dropper post on my bike. Shimano’s option of having a left lever dropper actuator is perfect for that setup. It also gives me the opportunity to compare the new GRX head-to-head with the SRAM Force XPLR AXS components I have on the Lauf Seigla I’m long-term testing.

First Impressions – Shimano GRX Press Camp

In mid-August, I traveled to Bend, Oregon for Shimano’s GRX press camp. There, we learned about the new GRX parts from Shimano’s product team, and had a chance to ride the new parts in Bend’s famous “moon dust” volcanic dirt. Unfortunately, heavy smoke from nearby wildfires limited our riding to just one day, so we had to make the most of our limited time. That said, the roughly 50-mile ride we did gave us a very good idea of what to expect from the new GRX group, with a healthy mix of singletrack, gravel roads and paved trails.

Bend, OR moon dust
Bend, Oregon’s famous ‘moon dust’ conditions were a great place to get a first impression of the new GRX. Image: Shimano

For the press camp, I rode a sweet Specialized Diverge STR equipped with the “Unbeatable” GRX group and RX-880 carbon wheels. While many editors at the camp were running the wider-range “Unstoppable” version of GRX, I found the gear range offered by the 10-45t cassette to be just fine for my legs. From what I could tell, there were only a couple editors on the 2x “Unroppable” iteration of the new GRX.

I have to say I’m stoked Shimano is still developing its 2x GRX groupset. A lot of riders still prefer 2x for gravel and most of my personal gravel bikes still run 2x drivetrains. That said, it’s easy to feel the winds of change blowing. That’s why I decided to go 1x with the new GRX.

My biggest takeaway from the GRX press camp is that the new group takes everything you love about GRX and makes it better, smoother, and more versatile. The new Hyperglide + cassettes shift to smaller/harder gears noticeably smoother than before. The brakes, while already very good, stayed quiet even after the longest descents, proving the worth of the increased pad retraction Shimano engineered into the calipers.

GRX swappable cages
A comparison of the two cages for the 1x GRX derailleur. The one on the left is for the 10-45t cassette, while the right one handles the 10-51t cassette. Image: MG

I also love the fact that Shimano designed the 1x GRX derailleur with swappable cages. That means I can take my mid-cage RX822-GS, designed for the 10-45t cassette, and swap it out for the longer SGS cage (for the 10-51t cassette) without needing to replace the derailleur itself. The GRX derailleur is the first Shimano derailleur to have this capability, and it makes perfect sense to me.

The new RX-880 carbon wheels were also impressive during my time at the press camp. Armed with Shimano’s latest Direct Engagement rear hub, the wheels feel fast, engage quickly, and aren’t too loud when coasting. They’re also the first Shimano wheels to feature an easy-to-swap cassette body, so you can quickly switch between the MicroSpline and the 12-speed HG L2 spline cassette bodies. The ride quality is on-par with the best wheels I’ve ridden too, making them a great fit with the new GRX drivetrain.

That’s especially important right now too, because the RX-880s are one of the few gravel wheelsets currently available with Shimano’s MicroSpline cassette body, which is a requirement for the new 1x GRX groups. It’ll be less of an issue going forward however, as more companies begin to offer MicroSpline-equipped wheels.

Overall, I left the press camp in Bend wishing we’d have gotten to ride more, but looking forward to spending more time on the new GRX groupset at home. The timing worked out perfectly, as I had a brand spanking new Mod Zero frameset from Black Mountain Cycles (which I bought and paid for) waiting for the new GRX parts to arrive.

My Long-Term Tester: The GRX-Equipped Black Mountain Cycles Mod Zero

MG's BMC Mod Zero
The new Mod Zero from Black Mountain Cycles is a great pairing with the new GRX groupset. Image: MG

While the frameset I chose for my long-term GRX test bike is quite different from the one I rode at the Shimano press camp, the differences from a parts standpoint were more subtle, including a shorter stem, a wider, more flared handlebar, a dropper seatpost, and a larger rear brake rotor.

I built my Mod Zero up with the same 1x “Unbeatable” grouppo as I rode at the Shimano press camp. I went with dual 160mm rotors, 175mm cranks, and a 40t chainring to go with the 10-45t rear cassette. For our local terrain, the gearing should work well, whether at party pace, or something quicker, and the larger rear rotor is simply based on my belief that 160mm rotors are as small as I want to go.

PRO Dropper 70 seatpost
The PRO Dropper 70 seatpost and Stealth Off-Road saddle are proven quality parts. Image: MG

A variety of PRO components rounded out the build, including a 46cm Discover Alloy 30 handlebar bolted to an 80mm Discover Alloy stem. Since I specced a dropper actuator-equipped GRX left lever, I mounted up a Discover Dropper Post 70 (70mm drop) topped with a PRO Stealth Off-Road saddle.

The stem, seatpost, and saddle are well known to me, so I chose them based on the fact that I knew they’d work for me. On the other hand, the Discover Alloy 30 handlebar was new to me. It’s 46cm width at the hoods flares out to about 58cm in the drops, thanks to the generous 30 degrees of flare. And with just 90mm of drop, it’s on the shallow end of the drop bar spectrum.

I bought a set of 47c Vittoria Terreno Dry tires (tubeless TNT casing) to mount up to the RX-880 wheelset. I’ve wanted to try these tires for quite a while, and this build was a great excuse to get a set.

First Rides on the GRX-Equipped Mod Zero

First, I have to say how happy I am that Shimano is continuing to invest in developing its high-end mechanical drivetrains. The new GRX groupset is a great choice for a wide range of riding, from gravel and adventure, to drop bar bikepacking (perhaps with a swap to a crankset with a smaller chainring).

It feels like the perfect compliment to my Mod Zero frameset. The shifting is light at the lever, and gear changes are incredibly smooth in both directions. The braking is strong, with a firm feel at the lever and easy modulation. Overall, the performance of the new GRX raises the bar for mechanical groupsets, and makes a compelling case for not paying more for an electronic group.

PRO Discover 30 alloy bar
Even with Shimano’s revised lever geometry, the extreme 30 degree sweep still angles the hood tops, as well as the levers. In use, they feel great. Image: MG

While I appreciate the ease of shifting that electronic groups deliver, on a day-to-day basis, I enjoy not having to think about whether my batteries are charged on my bike. That’s where the new GRX really shines. It’s the perfect ‘daily driver’ for riders who just want to ride for the love of the ride.

I might feel differently if I lived in a more mountainous state, but for the majority of the gravel riding I do, the 10-45t cassette gives me all the gearing range I need. Since I have several Shimano-equipped mountain bikes with 10-51t cassette, I can feel the smaller gaps between the gears on the 10-45t cassette I chose for the GRX build. I definitely prefer that feeling for my local gravel.

After about three rides, I swapped the front 47c Terreno Dry front tire for a 55c Rene Herse Fleecer Ridge tire with the Endurance casing. Despite the fact that it’s 5mm wider than the claimed 50c clearance, the Fleecer Ridge fits into the fork with clearance to spare. I wouldn’t try it in the rear however. The pairing of the knobbier 55c tire up front with a faster rolling 47c tire in the rear is a particularly good one on this bike. On our local (relatively flat, smooth) singletrack, I can confidently drift the rear tire in turns. Talk about fun… You bet!!

Initial Conclusions

When I think about where the new Shimano GRX groupset fits into today’s marketplace, I think it’s easy to see it’s the ‘people’s choice’ in terms of price to performance ratio. As I said earlier, I’m beyond stoked to see Shimano reinvesting in its next generation of mechanical drivetrains. Because while I do love the ease of electronic shifting for rides/races of 200+ miles, for my day-to-day bikes, I like the always ready nature of mechanical drivetrains.

Shimano GRX derailleur
The design of the new 1x GRX derailleur is based on Shimano’s excellent Deore XT MTB model, updated with a cable adjuster and revised pull ratio to work with the drop bar levers. The cassette is an actual Deore XT item. Image: MG

So while it’s cool to think about how much more inexpensive electronic drivetrains are becoming, ten times out of ten, I’ll take a bike equipped with the new mechanical GRX components over a bike specced with a lower-level electronic groupset from the ‘other S-brand’, or anyone else. I love not having to worry about charging (or changing) batteries. I can just ride and not be left wanting for anything more from my drivetrain or brakes.

Based on my early impressions of the new GRX, I have a feeling it’s going to be at least as impressive long-term as its predecessors. I still have two 11-speed GRX equipped bikes in my stable, and four years after they were built, I’ve only replaced chains and brake pads. The new parts feel just as robust, if not more. Time will tell, but that’s the beauty of long-term tests. We’ll find out.

Thanks for reading! Please leave any questions or comments you have below and I’ll get you answers as quickly as possible. And look for my ‘Checkpoint’ review of the new GRX grouppo down the road a bit.

In the meantime, learn more about the new Shimano GRX components at

Please note: Shimano paid for my travel and expenses at the GRX press camp, and sent the new GRX groupset, RX-880 wheels and PRO components to Riding Gravel at no charge for long-term testing and review. I’m not being paid, nor bribed for this review, and my sentiments about the products on review are solely my own.


Author: MG

Matt Gersib is the 2014 Gravel World Champion in the Fatbike category. He's also finished some of the most challenging gravel events in the country, including the Dirty Kanza XL, TransIowa and the Dirty Kanza 200, among others. In 2015, Gersib was an inaugural inductee into the DK200 "1,000 mile club" of five-time finishers. In addition to his gravel cycling, Gersib is an accomplished mountain bike racer, with numerous race wins and championships, including the 2012 Nebraska State Marathon MTB Championship.

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4 thoughts on “Shimano GRX 12-Speed: Getting Rolling

  1. Thanks for the review, I see a 12 GRX Drivetrain in my future! I’d also be interested in your impressions of the ModZero since it’s a frameset I am considering.

  2. Hey Steve – Thanks for your comment. I only have a couple hundred miles on my Mod Zero, but so far I’m super stoked with it. I had high expectations, but they’ve been exceeded in every way. The new GRX compliments the frameset’s character very nicely too. I’m 6’1” tall and am riding a 56cm frame in the Mod Zero, where I’d usually ride a 58-59cm frame, so be aware of that if and when you place your order.


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