Gravel Grinder News: Shimano Announces 12 Speed GRX Groups: GT’s Take

Gravel Grinder News: Shimano Announces 12 Speed GRX Groups – by Guitar Ted

12 speed GRX drive train image.
Shimano introduces its new 12 speed GRX components

Today Shimano officially releases the much anticipated 12 speed versions of GRX, its gravel group set that Shimano first introduced in the Spring of 2019. GRX was the first dedicated to gravel components set and covered 10 speed mechanical, 11 speed mechanical, and 11 speed electronic groups. Today Shimano bumps up the cog count to 12 and adds some features and tweaks to GRX which we will take a closer look at in this post. For a detailed rundown of everything 12 speed GRX, see MG’s post on the release HERE. Some of the pertinent details will be repeated in this post for clarity regarding my comments.

You may have noted that the plural of “version” was used in the paragraph above. That is because Shimano is releasing three versions of 12 speed GRX at the 800 series level. Here’s what Shimano sent us in a press release which speaks to why they have done this:

The “Unbeatable” 1X version of GRX 12 speed.

With a focus on the heart and soul of gravel cycling, Shimano mechanical GRX receives this 12-speed
upgrade delivering top-tier performance without an over-the-top price. And since gravel is all about
personal expression and freedom to choose how and where to ride, Shimano GRX includes three unique
12-speed mechanical drivetrain personalities to cover the full spectrum of riders and rides.

Those three types of GRX are the following “Unbeatable” which is a 1 X 12 group featuring a close range 10T – 45T cassette, “Unstoppable” which is another 1 X 12 group, but features a 10T – 51T cassette, and then to close things out there is an “Undroppable” configuration, which is 2X, and features the wide range rings in a 46T and 31T crank set. This is mated to the offered 11T – 34T or 11T – 36T (maximum range) cassette.

The 2X 12 speed GRX

Comments: While many may roll their eyes at the naming convention, there is a real difference going on here. First off, you’ll note that the 1X groups have a 10T cassette cog. That’s right……it’s Micro Spline. This would be the first use of the new standard free hub body outside of Shimano’s MTB groups. That’s a big deal because it should put Shimano in a better position against SRAM’s wide-range cassette offerings and “mullet” drive train options. The drive rings range from 40T – 42T and match up with crank sets which range in lengths from 170mm – 172.5mm – 175mm. Pretty typical stuff there. But hold on…. There’s more, as Shimano has updated its 600 series GRX to be 12 speed as well. It is heavier, of course, but the interesting points here are that the group features a smaller drive ring choice (38T) and a one tooth smaller inner ring on the 2X (30T) with a shorter length choice in crank arms (165mm) and 1X crank sets are compatible with 10-45T and 10-51T cassettes.

An image showing a medium cage GRX rear derailleur superimposed over a 12 speed cassette and chain.
Shimano’s new medium cage GRX pairs with the closer range 10-45T cassette.

Derailleurs: Shimano has added a new twist to the rear derailleurs for the new 12 speed GRX with a medium length cage. The RD-RX822-GS medium cage rear derailleur is meant to be paired with the closer ratio cassette (10-45T) and the new RD-RX822-GSG long-cage rear derailleur is to be paired with the 10- 51T cassette. Both feature Shimano’s SHADOW RD+ chain stabilizer. Furthermore; the derailleur cage is swappable. The rider now has the ability to change or replace the derailleur cage between 1×12 options. This should come in handy in situations where the cage gets damaged, as you won’t have to purchase an entire new rear derailleur.

The 2X rear derailleur is the RX 820 with the same RD+ chain stabilization and has a maximum capacity of 36T. Note: Shimano did not specify that this rear derailleur has a swappable cage. The front derailleur paired with this rear derailleur is the FD-RX820 which has Toggle Link, wider tire clearance built in with its 2.5mm offset, and weighs in at 95 grams.

Comments: Hey….no Di2? We assume that is coming in the future. For now, we have these mechanical 12 speed group sets to check out. Interestingly the 610 series is not featured with its own rear derailleur or front derailleurs. All this a sign of the times when we see stock levels at all-time highs, we would guess. No need to double up on components since that would put an even greater burden on OEM’s and dealers. In fact, we’re surprised any GRX (or other Shimano components) are being introduced at all during this time.

The new 12 speed GRX levers look pretty familiar.

Shifters: The new 12 speed GRX gets new shifters, of course. Featuring a redesigned lever for better ergonomics while used with flared drop bars, the mechanically shifted, hydraulic levers are also compatible with dropper posts using the 1X specific left lever on the ST-RX820-LA option. The hoods feature texturing for better grip in wet and muddy conditions while the lever blades feature an “Anti-Slip Coating”.

Comments: Obvious upgrades here with no real surprises. I’m a little bit confused as to why the higher brake pivot wasn’t utilized as Shimano made a big deal about that with the Di2 GRX levers in 11 speed. Perhaps we’ll see a return of that with the new 12 speed Di2 GRX, when/if that comes out.

Cassettes: The 1X options of 10-45 and 10-51 are Micro Spline while the 2X options are standard Shimano road cassette free hub body compatible. Those are 11-34 and 11-36T. No technical data is given on the cassettes.

A GRX level 12 speed cassette
This looks a lot like a 105 level 12 speed road cassette.

Comments: To my eyes the HG cassettes look like they are 105 quality level (there is a new mechanical 105 group being introduced today as well, by the way) and the 1X options bear a strong resemblance to XT cassettes, if in fact they are not XT cassettes. There will be some wailing and gnashing of teeth due to the Micro Spline thing, I am sure, but my feeling is that we are all in the midst of a sea change to Micro Spline for everything 12 and up in the future.

Image showing the Micro Spline hub.
The new GRX Carbon wheels have the Micro Spline free hub option, and Direct Engagement feature borrowed from Dura Ace wheels.

Wheels: Shimano took this opportunity with the introduction of Micro Spline to GRX to revamp its flagship GRX carbon wheel set. The RX880 wheel set is claimed to be 64 grams lighter than the previous GRX carbon wheel set, and it features the new Direct Engagement hub design, a feature also found on new Dura Ace road wheels. This Direct Engagement free hub is easily swapped between Micro Spline and HG Direct Engagement free hubs and allows the owner of the RX880 wheels to swap from 1X to 2X GRX set ups without having two wheel sets. (NOTE: The Direct Engagement HG free hub body is not compatible with 11 speed cassettes)

Diagram showing how Direct Engagement allows for a choice of Micro Spline and HG types.
Direct Engagement allows riders to swap out free hub bodies.

The rims are similar to the old GRX carbon wheels in that they have the same depth, 25mm inner width, and 24 spoke count drillings. The spokes are “J” bend type so that replacements can be easily sourced, if necessary. Of course, these new wheels are tubeless ready.

Comments: I really liked the last Carbon GRX wheels and I suspect I would be thrilled with the new ones. The swappable free hub bodies are a cool touch, but it is a bit of a bummer that the HG one is not compatible with 11 speed stuff.

The Rest: Brakes seem to remain unchanged as they are not affected by the switch to 12 speed. Oddly missing is any reference to GRX 400 which was 10 speed and logic would follow that at some point this would resurface as an 11 speed group. However; with the economics of the industry being such as they are, we maybe are not going to see all the gaps filled in until much later.

Comments Overall: The move to 12 speed was not a surprise, and of course, we got a sneak peek last June anyway. The big deal here , in my opinion, is the Micro Spline thing. This not only opens up a wider gearing range option for riders right now, but it points to a future, again, in my opinion, where all of Shimano’s higher ranges (Road, MTB, Gravel) use that free hub standard. HG free hubs will always be with us, but in my opinion, they will eventually be seen in the same light as we see thread-on free wheel technology now.

Image showing a brake caliper and rotor.
Brake calipers and rotors carry over unchanged from 11 speed GRX

Bottom line? Nice enhancements in gear range choice, in the wheels, and with the expectations for a 12 speed group. GRX is a solid performing group that is aimed at unpaved road riding. It has a good reputation for performance and reliability. It needed a gearing range expansion to keep up with SRAM’s offerings, and now that is pretty much here. (GRX 600 1X 38T paired with a 10-51 cassette)

But it is disappointing to not see an electronic offering (yet) and the gap in 11 speed offerings is a glaring one. Unless 11 speed GRX continues on as is alongside this new 12 speed stuff. Again, with the current economic status of the cycling industry with specific regard to record high inventory levels, it maybe should not surprise us that we are not seeing everything Shimano has just yet.

Note: Riding Gravel received information and images for this post from Shimano North America. Comments are Guitar Ted’s and may not reflect the opinions and feelings of Shimano.


Author: Guitar Ted

Guitar Ted hails from Iowa. Home of over 70,000 miles of gravel and back roads. An inaugural member of the Gravel Cycling Hall of Fame and Co-creator of Trans Iowa in late 2004- Guitar Ted has been at the forefront of the growth of gravel events and riding since then. Creator of Gravel Grinder News in 2008, he produced the premier calendar of gravel and back road events. GT joined forces with Riding Gravel in late 2014.

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4 thoughts on “Gravel Grinder News: Shimano Announces 12 Speed GRX Groups: GT’s Take

  1. Dave Rome from the the Geek Warning podcast interviewed Shimano’s Nick Legan and Dave Lawrence and they confirmed a 12-speed GRX Di2 will be coming in the future, just not today.

  2. Hi, I’ve a Scott Speedster Gravel 30 with 2×10 GRX, I want to convert to the 1×12 wide range GRX RX820, 40t chainring and 10-51t cassette

    What are the parts that I can avoid changing from the current bike? I.e.: I want to retain the current caliper and rotors, can I do that? I understand that the rear hub must be changed to accomodate the 10t sprockte, will this force me to change the rotor?

    Can I keep the cranks and use spacers to center the chainring or is a terrible idea? 😀


    1. You might not need a new rear hub. Check with your hub manufacturer to see if they offer the Micro spline freehub as a swappable part. Some do, such as DT Swiss.

      You can keep every part of your brakes except of course the brake/shift levers. Unless your new hub (if needed) has 6 bolt rotors and the new one is center lock or vice versa. Then you’ll need a new rotor or adapter.

      It looks like your bike came with a Praxis Alba GR crank which can go to 1x with a DM1X Road/Gravel ring.

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