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Shimano GRX Di2 groupset review

24 Feb 2021

Page 1 of 2Shimano GRX Di2 groupset review


Solid, dependable, unflashy – the Shimano GRX Di2 groupset is exactly what we expect from Shimano

Cyclist Rating: 
Lever design • Modular component • Specific gravel features • Robust performance
11-speed gearing lags behind competitors

Cycling trends come and go but you can be sure when Shimano throws its heft behind something, that something is here to stay.

Admittedly gravel riding was already gaining momentum before Shimano jumped in with its gravel-specific GRX product family in early 2019, but it has undoubtedly helped cement gravel as a bona fide discipline.

Today’s gravel bikes no longer need to be a cobbled-together mix of road and mountain bike components, which makes it slightly curious that this is essentially what GRX is. Shimano says it has taken aspects from both its road and mountain bike ranges and homogenised them to suit the particular requirements of gravel.

A big advantage of GRX is that it is not just a single groupset but rather a family of components that can be purchased in pick ’n’ mix fashion to take on different guises across various price points.

GRX can be configured as 1x or 2x, so take your pick as to whether you go for the road or MTB influence, but either way there are sufficient options to ensure no one should be left wanting when it comes to setup options.

Shifting opinion

The GRX rear derailleur is definitely more influenced by XT (MTB) than Ultegra (road), while the brake callipers and disc rotors are essentially unchanged from the road product offering.

This isn’t to say GRX is just an exercise in rebranding. The rear derailleur’s clutch tension is specifically tuned to be lighter than Shimano’s mountain bike products to match the lower impact forces of gravel riding.

The manufacturer says the simple manual on/off clutch lever ‘offers the best solution for chain management in terms of price, quality and usability’, and on the whole I’d agree.

It’s a little less sophisticated than Sram’s Orbit fluid damper used on its AXS rear mechs but this is clearly reflected in the costs. For comparison a GRX Di2 RX817 rear derailleur is more than £100 cheaper than Sram’s Force AXS, which is an important consideration in an off-road environment where rear derailleurs are more vulnerable to damage.

Buy the Shimano GRX Di2 groupset from Freewheel now

The Shimano clutch system is no less proficient in use, though. I never once experienced a dropped chain in testing, helped too by Shimano’s Dynamic Chain Engagement tooth profile used on its 1x chainrings. This technology has been a successful part of the brand’s mountain bike groupsets for more than five years to boost chain retention.

A key feature unique to GRX is the shifters, and in my opinion this is the groupset’s biggest triumph. For starters, the brake lever axis on the Di2 levers is positioned 18mm higher than on Shimano’s road levers.

While I typically try to descend and ride rough terrain in the drops, it’s all too easy to get caught unawares and out of position on technical trails. I found the increased leverage a welcome feature as it made generating braking power from the hoods a lot easier.

The new shape of the lever blades backed this up well too. The face of the blade is wider and flatter, with a subtle groove near the top that fits your index finger nicely when riding on the hoods.

The lever blade is also more angular and even has a matte finish instead of the gloss used on Shimano’s road levers. The brand says this is all in an attempt to improve purchase and I’d definitely say that aim has been achieved.

Topping off the accomplished design nicely are the ribbed hood covers. I found the pronounced ridges promoted an assured hold even when my hands were coated in sweat and grime – as they so often are at the business end of gravel rides.

Buy the Shimano GRX Di2 groupset from Freewheel now

Gearing up

Gearing is both a thorny and a subjective issue in whatever discipline you ride but when it comes to gravel 1x is increasingly being seen as the best solution. It presents few disadvantages, these being primarily range and sprocket progression.

While I think Shimano has gone about solving its GRX 1x offering in an excellent way – I was never left wanting with the well-spaced 11-40t cassette and 40T chainring setup – I couldn’t help but think it’s a shame that Shimano didn’t opt for 12-speed as per its top-end mountain bike groupsets.

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Sram has had 12-speed for some time now and Campagnolo recently released its 13-speed Ekar groupset. The harsh perspective is that GRX is now sitting third wheel behind its main competitors in terms of sprockets on offer.

‘Considering GRX’s origins are from a drop handlebar perspective, a 12-speed option would have required developments and technologies not within Shimano’s current road product offering,’ came the rationale from Shimano’s Ben Hillsdon when I discussed the matter with him.

I find that hard to accept. Knowing that Shimano has already deployed 12-speed in its mountain bike line, and given GRX already borrows heavily from mountain bike products in other areas, not bringing 12-speed across, particularly at Di2 1x level, seems like a missed opportunity.

Given that a change in freehub design would likely be required to accommodate more (smaller) sprockets, wheel compatibility is likely a large influencing factor here (as it stands, keeping GRX at 11-speed allows for the seamless use of any current Shimano-compatible road wheel). But on the other hand, in its Ekar-stimulated move to the N3W design, Campagnolo has shown that the shift to a new freehub standard isn't an insurmountable task.

I guess we’ll just have to wait for Shimano to go 12-speed on the road before we see a gravel update, but I’d wager that might not actually be too far off. Watch this space.

Buy the Shimano GRX Di2 groupset from Freewheel now

My minor personal frustrations at Shimano’s logic aside though, I can’t deny the groupset’s performance is well-balanced and really hard to fault. GRX Di2 undeniably still holds its own against the competition and is precise, specific, robust and innovative.

If and when a 12-speed update arrives at some point in the future it will merely stand to even more firmly assert GRX as some of the most worthy components for a gravel bike that money can buy.


Chainset GRX 810 Hollowtech II, 40T 
Shifters GRX RX815
Rear derailleur GRX RX817
Brakes GRX RX810
Rotors Ultegra RT800
Chain Ultegra/XT M8000
Cassette Deore XT M8000, 11-40t
Price £1,638.89 as tested

All reviews are fully independent and no payments have been made by companies featured in reviews

£1,638.89 as tested

Page 1 of 2Shimano GRX Di2 groupset review