Colin reviews the Shimano GRX RX820

Back in 2019, Shimano announced GRX, the first gravel-specific groupset. Following the clutched Ultegra RX rear mech launched in 2018, Shimano borrowed bits and pieces from its road and MTB components to create a system designed to cope with mixed terrain riding.

Five years on, Shimano has given GRX an overhaul, unveiling three flavours of new 12-speed GRX RX820 components. As part of the official launch, I was invited to Bend, Oregon, to spend some time on the new GRX and have since had it bolted onto a Scott Addict Gravel to put it through its paces all over South East Queensland and Northern NSW.

Related

• 2024 Scott Addict Gravel Tuned | A gravel bike all about hot, nasty, badass speed
• Fresh Produce | Reserve 25 |GR Gravel Wheelset
• Maxxis Gravel Tyre Range | From the chunkiest to the slickest

What’s New With Shimano GRX?

GRX 12-speed is divided up into three distinct groupsets:

• Unbeatable: 1×12 with a 10-45T cassette
• Unstoppable 1×12 with a 10-51T cassette
• Undroppable 2×12 with 11-34T or 11-36T cassettes

W had expected to see both the mechanical and Di2 groupsets breaking cover, however for the time being, GXR 12-speed will be limited to mechanical. Six months on there is still no word on when we’ll see Di2 add the extra cog at the back, but Shimano has assured us that it’s coming. 

Overall, Shimano’s GRX is a boring groupset, but that’s why it’s so good.

According to Shimano North America Road and Gravel Product Manager David Lawrence, the reasoning behind that is 75% of the gravel market is mechanical, so they’re aiming to satisfy the bulk of the market before updating the HALO gear.

A big point that Shimano stressed during the launch is that it aims to keep gravel accessible for all kinds of riders, whether it be folks looking to sign up to Unbound or SEVEN or those simply looking to get outside and do some exercise. The shockwave from gravel has well and truly overtaken the North American market in the last few years, and the swell is still growing in Australia. But this aim to have something for every type of rider is part in parcel to why Shimano offers both 1x and 2x versions of the new groupset.

In this same vein, Shimano is also trickling 12-speed down to the RX610 level groups however, cheaper components are limited to shifters and cranks.

With a tighter gear range and a 10-45T cassette, the Unbeatable group is pitched at gravel racers. The 51T dinner plate on the back of the Unstoppable group — which is what I have been riding —  leaves slightly bigger jumps between cogs, and this set-up is pitched towards the folks after big adventures way out in rugged and varied terrain. The third Undroppable offers closer gear steps still for those who still prefer 2x on a drop bar platform.

Beyond the cassette, both derailleurs are based around the Shadow+ design with an adjustable clutch — or chain stabiliser as Shimano prefers it to be called — the parallelogram, and everything else are identical, the only difference between these two groups is the derailleur cage. The GS (mid) cage only capable of spinning a 45T cog, while the SGS (long cage) can take the 51T dinner plate. This new derailleur is designed to allow these to be interchanged. However, Shimano AU tells Flow it won’t be stocking the replacement cages.

The gear levers have had some tweaks to the ergonomics to more equally spread the pressure across the heel of your hand. Shimano says it has changed the angle of the band clamp to match 16° flared drop bars and create a flatter surface across the hoods. This change isn’t immediately noticeable, which arguably means it’s achieved its goal. I also rode the levers bolted onto non-flared bars, and had no issues with discomfort or hotspots. 

The brakes have also been brought in line with the two-piston, flat-mount stoppers rolled out across the road groupsets earlier in last year. The pad clearance has been increased by 10%, and the bleed port has been moved to the outside of the calliper body for easier access. That second part is a major improvement.

Seemingly under the radar, earlier this year Shimano also revamped its centerlock rotors and made a point to guide our attention to them. These aren’t just for GRX, and CL 800 and CL 900 rotors will be available in sizes from 140mm all the way up to 203mm. Shimano claims to have further improved heat management with its Ice Technologies Freeza construction. This is paired with a more robust arm structure that’s said to resist heat deformation during hard braking better.

Shimano GRX RX820 prices

Shimano’s GRX is roughly in line with its second-tier groupsets, combining XT and Ultegra. With the lack of batteries and wireless communication protocols, the cost of these parts has a refreshing lack of commas in the RRP. Here’s a breakdown of how many dollarydoos a GRX 12-speed upgrade will cost;

• Shimano GRX Rear Derailleur — $189 AUD
• Shimano GRX 1x Crankset w/40T Chainring — $370 AUD
• Shimano GRX RH Shifter & Brake Calliper — $603 AUD
• Shimano GRX LH Shifter & Brake Calliper — $466 AUD
• Shimano GRX 10-51T Cassette —$240 AUD
• Shimano GRX Chain — $75 AUD
• Shimano GRX Wheelset — $2,199 AUD
• Shimano GRX CL 800 Rotor 160mm — $109 AUD
• Shimano GRX CL 800 Rotor 140mm — $109 AUD

GRX mechanical provides the gear range, a distinct lack of batteries and should hit decent pricing on complete bikes.

Shimano GRX RX820 weight

And while we’re at it, here are the actual weights for each of the components—bar the chain, because who weighs a chain, right?

• Shimano GRX Rear Derailleur — 295g
• Shimano GRX 1x Crankset w/40T Chainring — 642g
• Shimano GRX RH Shifter  — 298g
• Shimano GRX LH Shifter — 232g
• Shimano GRX Front Brake Calliper w/ adaptor and hose — 166g
• Shimano GRX Rear Brake Calliper w/ hose — 167g
• Shimano GRX 10-51T Cassette — 473g
• Shimano GRX Wheelset — 1,430g
• Shimano GRX CL 800 Rotor 160mm — 112g
• Shimano GRX CL 800 Rotor 140mm — 94g

KISS — Keep It Simple Shimano, reducing SKUs for bike shops

In among the three groups, the levers, brake callipers, and derailleurs have all been redesigned, however Shimano is leveraging a similar ethos to its CUES groupset in an effort to simplify its range and cut down the number of SKUs that bike shops need to stay on top of. With that, the RX820 crankset remains unchanged from the 11-speed to the 12-speed groups.

Given how difficult it has been to come by certain components over the last few years, simplifying things and making more pieces of bikes cross-compatible is a good thing.

So if you have 11-speed GRX on your bike and want to add a cog at the back, you won’t need to replace the crank. 

The same goes for the cassette and chains. The 10-51T and 10-45T cassettes are literally XT cassettes — they even have the XT graphic on the back — and the 2x clusters are simply the Ultegra and 105 cassettes. Each groupset will come spec-ed with an M8100 chain which is the XT/Ultegra level 12-speed chain.

Shimano GRX embraces the mullet

Up until now, Shimano GRX was simply outgunned by SRAM on gearing. SRAM has had 12 cogs at the back for quite some time, and you could run an Eagle derailleur and a 10-52T cassette on your gravel bike with just about any level of the drop bar shifters. That meant 2x road gearing to 1x MTB ratios, and everything in between was available for AXS and mechanical groupsets.

Shimano’s 1×11 GRX was officially limited to a 42t cog, while 2x could only take a 34T. Shimano is typically pretty conservative with its max recommended specs, and you could get away with slightly larger gearing — I’ve personally used a 40T cassette on a GRX 2×11 setup — but even still, SRAM had an extra cog and up to 10 extra teeth.

Now Shimano has closed the gap.

To achieve this, Shimano has employed its existing cassettes and chains, meaning GRX can leverage some of the key tech found across the brand’s other groupsets — namely Hyperglide+. You’ll find this across the gearing for the GRX range except for the 11-36T, as this is the 105 level road cassette.

This provides a substantial gear range that will allow you to attempt climbs where you’re arguably more limited by the traction of your rear tyre than by how many watts it takes to turn the cranks over.

Where is the 44T?

With 40 and 42T aluminium chainrings and a 38T steel RX610 level ring available from Shimano, the gear range more or less matches what a 2x setup delivers, and it opens up a fair bit of terrain — especially around Flow’s SEQ HQ — where previously a hardtail would have been better suited. Not because of the technicality of the riding but simply for access to a lower gear to keep spinning rather than grinding.

While Shimano is only offering the three chainring sizes for now, several third-party outfits, like Wolf Tooth Components, offer 110 BCD rings ranging from 36T to 46T. I’d love to see Shimano offer a few more options, namely that 44T chainring which in my experience is a bit of a goldilocks with a wide range cassette in terms of having enough low-end range to get you up and over a climb, while still enough oomph so that you don’t spin out so quickly.

Dinner plate at the back

Both my test bike at the launch, and the Addict Gravel were equipped with a 10-51T cassette and paired to a 40T chainring. This provides a substantial gear range that will allow you to attempt climbs where you’re arguably more limited by the traction of your rear tyre than by how many watts it takes to turn the cranks over. 

With such a small chainring on the front on flat well-graded terrain, I was often sitting pretty close to the end of the block, though with my recent level of fitness, I appreciated also being able to spin up climbs that usually result in a slow grinding slog to the top. However that 10-51T range does result in some sizeable jumps between gears.

While the largest jumps are towards the top of the cassette, I always seemed to get caught out around two-thirds of the way down the block, in the 21-14T range where the largest gap is 16-gear inches.

On singletrack these jumps are muted slightly because your cadence is much less steady as you’re negotiating rocks and roots, jumps, humps and switchbacks, and you’re also shifting quite a bit more. In this gear range 10-45T cassette has the same cogs, and so does a SRAM Eagle 10-52T cassette. In the case of the SRAM EXPLR  cassette — which tops out at 44T— where the others have even-numbered teeth, the EXPLR cogs are odd numbers (15,17,19,21) and for the way my legs spin seem to feel a bit nicer.

Clean and crisp shifting

As I mentioned before, this is literally an XT cassette, complete with Hyperglide+ and the shifting is extremely clean and crisp, even when dirty and under power. 

To be honest, this is probably the least surprising revelation since the sky being blue or water being wet. Shimano’s mechanical mountain bike shifting is exceptionally snappy, even on the lower-end groupsets, thanks to the ramping carved into the sprockets on the cassette and the architecture of the chain.

Part of the reason we opted for a Scott Addict Gravel as the test steed for GRX was due to the headset cable routing. Now I can already hear folks’ heads exploding in the comments sections about seeking out what is, across the board, a pretty unpopular feature; however, the reason for this is that routing the shift cable through the headset and into the frame forces it around some pretty darn tight corners. Most of the time, we try to avoid tight bends as it can cause mechanical shifting to create a racket that rivals a two-year-old who’s been given a set of maracas.

Sensitive to cable tension

On the first couple of rides there was a bit of noise and ghost shifting that developed as things settled in, but it took nothing more than a quarter turn on the barrel adjuster to dispatch the rattling, never to return. The same thing happened at the launch in Bend, with a few other editors’ bikes developing some noise over the course of our time on the bikes, again solved with less than half a turn of the barrel adjuster. 

It seems that the new GRX RX820 is a bit sensitive in this regard, and cables and housing stretching and wearing in can throw things out ever so slightly, but this is hardly unique to this groupset. That said, cable stretch is a non-issue when there is no shift cable in the conversation, but I digress. 

The derailleur itself looks extraordinarily similar to an XT mountain bike derailleur, and that’s because this is what it was designed after. At the launch Lawrence told Flow Shimano essentially added a barrel adjuster to the architecture of the XT mech. 

On that note, even though the actually wrangling the chain up and down the cassette is done with a modified XT derailleur, you can’t pair it to an XT shifter should you be looking to build a flat bar gravel steed, as the cable pull ratio between the STI and trigger shifters is different.

GRX Shifters

According to Shimano it made a raft of changes to ergonomics of the GRX mechanical shifters, the most notable being adapting the band clamp to play nicer with flared handlebars which have become just about standard on gravel bikes.

If I’m being totally honest I can’t say I noticed any difference, which is probably exactly as it’s intended. I did however appreciate that the size of the ridges on the hoods had been reduced as the texture on the 11-speed shifters used to tear my hands up. I’m also happy to see that the tacky coating on the lever blade borrowed from the fishing side of the business has been carried through — something I’d love to see on the MTB brake levers too!

With the number of teeth on the internal ratchet increasing by one, it has also reduced the lever throw. Shimano tells us this wasn’t a specific engineering outcome, by my measurement, there is about a 20mm difference between 11-speed and 12-speed shifters. It may not sound like much, but it was the first thing I noticed when I swung a leg over a bike at the launch. 

However it’s in the ergonomics of the shifters that I think Shimano is well and truly whiffed. While the GRX Di2 shifters look reminiscent of something out of a Predator movie, I LOVE the shape, and I know I’m not alone in this regard. The profile and recessed finger notch lock your hands in, and the position of the lever pivot and the shape of the blade allow significantly more leverage riding in the hoods. 

While I am cognisant that there are quite a few extra parts that need to go into a mechanical shifter compared to an electronic one, I wish that Shimano would push more to emulate the shape of the Di2 lever. This is an area where SRAM still remains a step ahead of Shimano with its mechanical Apex Shifters being a dead ringer for their electronic counterparts.

RX880 wheels bring Microspine to gravel

Alongside the GRX launch, the Japanese outfit also unveiled a set of Shimano carbon gravel wheels. It was stressed to us that these are Shimano non-series wheels, not GRX.

With the ultra snappy WH-RX880 name that totally rolls off the tongue, they feature a 32mm deep carbon rim with a 25mm internal width and a hooked tyre bead. Priced at $2,199 AUD, Shimano says they’re ideal for tyres between 32mm and 50mm, and they tipped the Flow Scales of Truth™ at 1,430g with the Microspline freehub body.

This is to accommodate the 10T smallest cog on the 1x MTB cassettes, however this hub is also designed to work with Shimano’s HGL2 freehub body. Not to be confused with the HG hub body we all know and love, HGL2 is only compatible with 12-speed cassettes with an 11T cog. Typically you’ll find HGL2 freehubs paired with Shimano’s road groupsets, however they’re also found on the 2x GRX. This swapability is a first for Shimano branded wheels, or hubs rather.

At the time of writing the gravel wheels available with Microspinle freehubs is still growing, but similar to when SRAM rolled out it’s XD/XDR driver it took a minute, but now they are ubiquitous.

The hub itself uses Shimano’s ratchet ring-based Direct Engagement system, and we’re happy to see that they spin on cup and cone bearings. While they take a bit more work than disposable cartridge bearings, with a bit of elbow grease you can keep them spinning smooth for aeons. Shimano wasn’t able to confirm exactly how many degrees of engagement on the ratchet ring. Still, it wasn’t obscenely loud, and it didn’t have a noticeable dead stroke between the ratchet teeth connecting you get with a cheap low-engagement hub.

With that said, when you do start pedalling again there is a notable clang when the teeth re-engage especially if you ratchet the cranks to get over something. It’s not the same sound as when pawls don’t engage properly, but against an otherwise sensibly quiet hub it does stand out.

With a stiff carbon rim, they track well through corners and don’t turn into flexi pieces of overcooked spaghetti when you ride through a nasty rut at speed. At the same time they don’t rattle your fillings out when things get a bit chattery — keeping in mind that tyre pressure and casing is also a factor here.

Shimano has struck a good balance between damping and stiffness for precision here. 

At a tad over 1,400g, they’re not blowing the doors off the weight weenies clubhouse, but they do wind up in a hurry and mind their manners when you get stuck in a blustery crosswind. 

It’s always hard to quantify durability in a review unless something actually breaks, however in my testing period I did slam the rear wheel into a cattle grid travelling somewhere in the vicinity of 50kph. It was quite the impact and resulted in an impressive roostertail of sealant spraying from the snake bike hole in my tyre. Of course, this is a purely situational observation but the rim was totally free from damage and spinning true as the day it came out of the box.

Can we learn anything from GRX about the next generation of MTB components?

In short, not really. GRX was the last of the Shimano family of performance groupsets to offer 12-speed gearing and has borrowed quite a bit from the current range of MTB components.

While GRX still opts for a traditional derailleur hanger, instead of a direct mount solution like SRAM’s Transmission, we wouldn’t necessarily rule out the next generation of MTB rear mechs going the same direction. Very few gravel bikes utilise a UDH, so it wouldn’t make a whole lot of sense in this category — yet. However, given that SRAM convinced just about every mountain bike brand to adopt this standard, and a Shimano patent from mid-2022 shows a “coaxially” mounted rear mech, it may still be on the cards.

Given the amount Shimano devoted to inclusion, making things accessible and targeting the bulk of the market in the launch presentation, if I had to speculate, I would expect we’ll see more mechanical shifting in Shimano’s next generation of MTB groupsets. That said, the internet has also revealed a Shimano patent for a wireless electronic derailleur and revived XT Di2 for e-MTBs, so who knows!

But, following the launch of CUES, the road groupsets and now GRX, MTB has to be the next cab off the rank for a remodel.

Flow’s verdict

A good groupset is one that is objectively boring. The type that doesn’t get its undies in a bunch when you miss time a shift, and still glides up and down the cassette when you go for your third consecutive ride in the rain without having so much as cleaned your bike or even wiped the chain down — whoops!

And for better or worse the new GRX is reliably boring, which is why it’s so great. It works very well in the dry, in the wet, when it’s dirty and even covers for you when you’re totally cooked and shifting requires about two-thirds of your available brain power. 

I can appreciate the ergonomic changes that Shimano has made to the shifter and embracing the evolution, not a revolution on something that is already very good. However I feel not steering more towards emulating the shape and size of the Di2 shifters is a missed opportunity. 

Shimano is typically pretty conservative when it comes to new tech — though there are exceptions to this rule — and up to this point, GRX has been a little bit off the back of SRAM and even Campagnolo in some respects.

While GRX 12-speed is limited to mechanical shifting for now, it’s clear Shimano has been quietly listening and watching what the market says it wants. Most folks are buying gravel bikes as second or third bikes, and aren’t looking to spend five figures. Many loud voices have also been decrying the slow death of analogue shifting across each category. GRX mechanical provides the gear range, a distinct lack of batteries and should hit decent pricing on complete bikes.

With that said, I’d love to see the brand offer a powermeter for GRX as it does with Ultegra, for which GRX shares half of its DNA. 

There are a few bits of this latest release that may seem a bit piecemeal on the surface — using an XT cassette and not even branding it GRX and not updating the crank. However, I think this is awesome and plays into the ethos of simplicity that Shimano aims to achieve with CUES. Plus, without an appreciable gain in performance; there’s not much point.

By and large, at this stage in component innovation, cranks are largely cranks, and cassettes are largely cassettes if you’re making apples-to-apples comparisons, i.e. crank length, material, cassette range, price point etc. Given how difficult it has been to come by certain components over the last few years, simplifying things and making more pieces of bikes cross-compatible is a good thing.

No, this doesn’t often lead to sexy new bits you can bolt on your bike, however simplicity and reliability rule the day — especially when you’re out in the middle of nowhere. It seems that’s what Shimano was striving for with GRX 12-speed mechanical groupset.

Overall, Shimano’s GRX is a boring groupset, but that’s why it’s so good.

ABOUT THE REVIEWER - Colin Levitch

Hometown

Gold Coast, QLD

Height

175cm

Weight72kg

RIDING STYLE

Aggressively mediocre