Shimano GRX RX820 Mechanical Gravel Groupset review

Chipps, perhaps perversely, specified his test on Shimano GRX RX820 to cope with gravel riding that was more mountainous than groomed, how did he get on?

• Brand: Shimano
• Product: GRX RX820 Mechanical Gravel Groupset
• From: Freewheel
• Price: STi levers including brake calipers: £349 (right) £329 (left). Chainset £229. Rear mech £119. 10-51T cassette £159.99. Rotors £54.99. Chain £49.99
• Tested by: Chipps for 6 months

Pros

• The lever and hood shape. A very comfy place to spend a long time.
• That 40 x 51T complete bailout gear.
• Honourable mention to the Genesis Croix de Fer Titanium frame. That frame with DT Swiss wheels and GRX groupset makes an amazingly versatile rig.

Cons

• A greater reach adjustment on the brake levers
• Chainrings in more than just two sizes (40 or 42T)
• UDH compatibility. Hey, it’s a wish list, OK?

When ‘new’ GRX RX820 was launched at the end of last summer, I was very interested to get to try it. For years, my cyclocross bike had been running a mishmash of Shimano GRX and Ultegra, to give a wide ranging 2×11 setup, with GRX Di2 shifters (and its great brakes), a GRX RX600 46-30T chainset and an Ultegra Di2 mech, just ‘cos that’s what I had. However, I’ve spent a load of time on SRAM XPLR 1×12 groupset and was keen to see how they compared.

I was keen to try to GRX 820 in its one-by incarnation because it would let me run a mountain bike-like 10-51T XT cassette and a single ring. Yes, I realise that not everyone wants a massive one-by range on their gravel bike, but I do. I’ve banged on before about how I think that there are two, distinct camps of gravel riding: There’s ‘American’ or ‘London’ gravel, where a rider clips in, rides flat out for four hours of mildly rolling, fine cinder towpaths and farm tracks, has a cappuccino and avocado toast and then rides a couple more hours home. This style of riding is where aero wheels, Lycra shorts with pockets and file treads make loads of sense.

Then there’s ‘Northern (UK/Canada/Europe) gravel’ where it’s more akin to 1990s mountain biking. Trails tend to be narrower, more natural and less predictable, with more emphasis on bike handling skills (and fun). There’s a lot more ‘Ooh, what’s down there?’ on/off road riding and climbs tend to be unrelenting and steep. The same goes for descents. This is where we see gravel bikes with chunkier tyres, perhaps a small travel suspension fork or dropper post and where the need for gear range over smooth cadence dominated. This is where I do all of my gravel riding. I have a SRAM-equipped Rä gravel bike with SRAM’s XPLR groupset (and its 1×12 10-44T x 38T chainring gear range) that regularly sees me grovelling in bottom gear for an hour.

Shimano’s UK distributor, Madison, was kind enough to install the group onto its flagship Genesis Croix de Fer Titanium frameset, complete with a nice set of DT Swiss Microspline wheels. At launch time, the only Shimano Microspline option was the £1200 carbon rimmed GRX wheels, but these DT Swiss hoops have been marvellous.

Starting at the front of the bike, let’s check out how the flagship gravel groupset lines up:

RX RX820 STI brake/shift levers

Shimano’s road STi levers have been around since the late nineties, and have evolved nicely with the times (with hidden cables and the addition of hydraulic brakes) to what we have here.

GRX brake/shift levers use the intuitive ‘pull for brakes, swipe the lever sideways for shifting’ action that is very easy to get used to. GRX differs from an equivalent Ultegra lever with a differently shaped lever blade – a matt-textured, anti-slip blade that’s flattened at the front for ‘finger on the lever’ comfort instead of the rounded and polished, more aero Ultegra lever. Shimano gets points for making the reach-adjust 2mm Allen key relatively easy to get to without disassembly of the hoods (though I would still like more ‘in’ adjustment for those with small hands, or ergo bars that put your fingers further from the levers). The hoods, too, deserve mention, as they’re far more aggressively textured for muddy hands to grip on to than road hoods. At the same time, though, the hoods are relatively round in shape, so that if you’re on a bike with flared bars, you’re not forced to rest your palm on a ‘corner’ of the hood, as you would if the hoods were squarer in shape for on-the-tops comfort on road bars.

Shifting action was reassuringly mechanical-feeling, without any plastic ‘clacking’ and the levers shifted smoothly through the dozen gears available. Shimano’s road brakes are generally excellent and here we get the finned brake pads and Freeza discs more familiar to mountain bikers, although GRX calipers are flat-mount only (and always have been). If you’re looking to modernise an older gravel/adventure bike, GRX doesn’t officially make post-mount or IS-compatible calipers (though some unofficial workarounds are available…)

Gears: 1×12 10-51T

Going back to the gears, when GRX RX820 was announced, there were three options – a 2×11 groupset as we’ve already mentioned, and then two 1×12 setups. I chose the 1×12 10-51T setup because I wanted a wide range of gears and didn’t mind having bigger jumps between ratios.

Over six months of weekly use, the Croix de Fer has been used on everything from almost-mountain-biking on very chunky trails to smoother gravel tracks. I even banged out a 100km road ride to see how the gearing and comfort of the system fared under longer rides. The system performed very well in all of those situations, with the wide range of gears coming into their own on extremes of terrain – with the super steep climbs and equally steep descents of my local terrain serving as a great test. If you live, ride or plan to ride somewhere flatter or more rolling, you may benefit more from the 2×12 setup, but for what I ride, the 1×12 has been great.

GRX Brakes

The Croix de Fer came with ‘stock for gravel’ 160/160 rotors, which proved fine for both choppy, technical moves and long, draggy descents too. The Freeza rotors and finned brake pads both offer a claimed temperature reduction of 50°C each and I certainly noticed no pump or fade, even on 15km downhills [Ed – #humblebrag]. Despite Shimano’s Servo Wave technology included in GRX levers, I feel the previous generation had a little more ‘snap’ in whizzing the pads into contact with the rotor, but both GRX incarnations give great power and modulation. As mentioned, the flat-mount only is going to limit riders with older frames, but any gravel/cross and even some hardtail frames from the last half dozen years should be a direct fit.

Final thoughts: GRX RX820

I did kind of expect a ‘choir of angels’ moment with the GRX group, given that the original Shimano GRX was pretty genre-defining when it was launched in 2019. Perhaps it shows that Shimano got it pretty much right the first time, five years ago, (a little like it did with the SPD pedal). Modern GRX 820 by comparison only really adds an extra gear… The braking is still great and the shifting is crisp, even across some pretty extreme chain angles. Would I prefer a 2×12 system for the riding I do? Not really – even though it’s obviously where Shimano is putting most of its focus. 2×12 is well-suited to ‘commercial’ gravel racing, where events are more like dirty road races. However, I feel that the 1×12 system, with its simpler cabling needs and lack of chain jamming and dropping (and perfectly adequate spread of gears for most people), is probably of more interest to riders coming from mountain biking rather than from the road.

I’d moan about a lack of Di2, but then it’s obvious from looking at the road (and previous GRX) developments that electric shifting is going to be arriving very soon for GRX. And, I am aware that Di2 off road is usually the preserve of pro racers and pampered journalists. Adventure riders are far more likely to want something that doesn’t need recharging.

Overall

After six months of use, Shimano’s new GRX RX820 is a great groupset for gravel riders who need a good spread of gears, faultless braking and reliability. It was only the success and ‘right first time’-ness of ‘old’ GRX that makes it feel slightly disappointing. And that’s purely because GRX RX820 simply gets on the job at hand without any fuss.

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