What is GRX? Shimano’s dedicated dropbar component series for gravel and adventure riding.
Key features? Wider gear ranges, overhauled brake lever and hood ergonomics, offset chainrings, clutch-equipped rear derailleurs.
Gearing options? 2×11, 1×11, or 2×10. Existing road cassettes are used for 2x setups, and mountain bike cassettes are used for 1x.
Unexpected things? Optional inline hydraulic brake levers and dropper post remote.
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Took them a while to catch up but, as a fan of shimano, I’m glad they have.
Seeing increased range at the back is very welcome as I’ve been put off changing the gearing on my bike because it required a wolftooth road link for any cassette cog over a 34.
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Two words: Gutted lever. 
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Good stuff Shimano, especially those levers and hoods.
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well that saves me the trouble of having to ask if an XT rear derailleur is compatible with an ultegra shifter. Now all I need to buy is one of these here gravel derailleurs and I can get up to a 40t cassette without having to go all wolf tooth on it. But hey while I’m here, is an XT rear derailleur compatible with an ultegra shifter?
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I wonder if we are getting a CX specific groupset from Shimano?
Not directly. Shimano uses a different pull ratio between road and mountain rear derailleurs.
You can use mix the two (road shifter + mountain RD) if you use the Wolftooth Tanpan.
I have one with a M8000 RD and an 11-40 cassette on my Boone. It works really well.
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I’m still waiting on my Di2 bell.
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I wonder if we are getting a CX specific groupset from Shimano?
My guess is this is it. 1x11 hydro with a Di2 option, what else can we hope for at this point? My guess is that the gravel scene is way bigger (and growing) than CX, so this is how they’re going to play it. But on the positive side it means there might be proper Shimano 1x CX bikes coming out this fall, for those of us who can’t abide SRAM.
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9 speed mountain RD works with 10 speed road shifters.
If the top CX riders want a 1x system Shimano aren’t going to have them riding anything without Dura Ace emblazoned on the side.
Dura Ace level version with better looking cranks would be my guess.
Mike
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I am using a XT DI2 derailleur on my gravel bike with a 42 cassette with no problems. I could go larger. Using a 40T chainring on an Ultegra crank. The main thing the new groups add is better braking ergonomics. I may just swap shifters some day.
Meh. It doesn’t seem to be well-thought out.
(1) They made a new line of products, which limits the appeal. Instead of offering something fully cross compatible, they pigeonholed themselves into a specific corner. So if you want to e. g. run 1x for a different purpose or run 2x with truly wide MTB gearing, you can’t do that with GRX.
(2) If you want a native Shimano 1x road setup, you still have to frankenstein yourself a drive train. The new cranks come only with 40 or 42 teeth, there is no option to go lower (38 or 36 teeth) and no option to go higher. The same goes for cassette options, there is no analog of SRAM’s 11-36 cassette. 11-34 has a narrower and has 2-tooth jumps straight from the beginning. So that cassette seems too small for amateur cyclocrossers. And it is unsuitable for people who want a 1x road setup, for example.
SRAM’s new eTap groupsets can be used from time trials to gravel riding. That makes deciding on a group set easier.
(3) Still just 11 speeds. It stands to reason that SRAM will release 12-speed mechanical groupsets next year. Campag is broadening its 12-speed range further downwards. And Rotor has 13 speeds.
(4) Admittedly, the extra hydraulic brake levers are cool.
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I just called Shimano.
I asked specifically if the new GRX 810 shifter (equivalent to Ultegra) will work with an XTR derailleur (in other words, with a mountain bike derailleur and cassette (11-42t, etc)).
The representative told me “no, the new GRX 810 shifter still uses the road cable pull, so it won’t work with mountain bike derailleurs.”
My interpretation is that the new GRX Shadow Plus RD-RX812 derailleur will accommodate an 11-42 mountain bike cassette while still using a road cable pull.
In other words, you’ll have to use the GRX derailleur instead of a mountain bike derailleur if you’re using GRX shifters, but the GRX derailleur will allow you to accommodate a mountain bike cassette.
Does anyone know if the GRX Shadow Plus RD-RX812 derailleur will be 2x compatible (the website seems to suggest “no”)?
A smooth 2x setup with road-style shifters and a wide range MTB cassette is my ultimate dream!
I currently use a 2x setup with Dura ace shifters with a Wolftooth tanpan device linked to an XTR derailleur, which woks, but it’s not very smooth!
I think the problem might be that the cage geometry is different between the 2x and 1x mechs. The jockey wheel on the 1x mech is much further away from the pivot so that it rotates further up into the cassette when there’s lots of slack in the chain. The difference in slack between the inner and outer chainrings may mean that it clashes with the cassette when it’s on the small chainring and is too far away when it’s on the large chainring. That’s the case with the SRAM 1x mechs.
Check out the difference between the two mechs at the middle of this picture.
Mike
Yeah. Very similar. I even have one of those but had forgotten that it was 2x compatible. On that basis, I think the GRX mech may well work 2x so long as the jump at the front isn’t too big.
Mike