Shimano shift gears with GRX 12-speed
Words and photography MIKE BLEWITT
The rise and rise of gravel racing and gravel riding is well-documented across the pages and feeds of cycling media.
You could argue that gravel riding started as the antithesis to road; a lukewarm counter-culture to a sport often stifled by rules.
An escape from the UCI was freedom, it was wind in the hair, it was outside, it was bikes.
Gravel was finding your own way on two wheels, away from the pressures to race.
Instead, it was about you and the outdoors – and probably some close friends.
As a close friend once reminded me, the best gravel bike is whatever you are riding right now.
But we all know bikes do make a difference and the bike industry made sure they evolved to suit.
Cyclists remained cyclists and sure enough gravel races popped up and have since become huge.
Shimano released its GRX groupsets just a few years ago in response to this, but in September 2023 it released three new 12-speed groupsets and a new wheelset to build on its existing expertise in gravel.
I spoke to Shimano product manager Dave Lawrence while in Bend, Oregon for the launch of Shimano’s 12-speed GRX groupsets in August.
His take was that GRX was the most popular choice early on, but as gravel riding and racing continued to change, there was room for improvement.
‘We only had one 1x option and the total range wasn’t enough.
The market was maturing and people wanted to go faster on 1x, but people also wanted something for all-day adventures, and not to have to get off and walk, ever,’ Lawrence said.
A lot of the discussion was about range, and it turns out that the mountain bike segment had the answer already, with both the 10-45t and 10-51t 12-speed cassettes.
Shimano had realised it needed two different 1x options to suit racers and riders, and it turns out the cassettes were there already ‘It was actually a pretty easy decision, but we still needed to make two new rear derailleurs,’ Lawrence admitted.
Tradition runs strong in cycling, so Shimano has also kept a dual-chainring option as tested here. ‘A fair amount of our sponsored racers come from a road background and they love having a front derailleur and close spaces on the gears.’
The three mechanical 12-speed groupsets talk to where Shimano sees more growth in cycling, as GRX isn’t strictly a gravel groupset.
It’s perfect for an all-road bike, and with 600 series 12-speed equipment also available you can expect to see a lot of bikes across a range of prices equipped with their latest 12-speed groupsets.
On the dirt with Shimano GRX 2×12
After the press launch, I received a Shimano GRX 820 2×12 groupset to test at home, along with the new RX880 wheels.
I had them built onto my Factor LS, which I had built up with Shimano GRX 2×11 just ahead of the Gravel National Championships in Tasmania in June.
Aesthetically, functionally and ergonomically Shimano’s 2×12 GRX groupset is very similar to the 2×11 setup.
However, there are some important changes that play a role in comfort, control, chain security and, of course, gear range.
On this test build I moved to some of the flared bars from the PRO range, as the new shifters are designed to work best with flared bars.
The result is a very comfortable position in the hoods, which have also had a revised pattern to the gripped rubber for the ideal match of comfort and grip.
In terms of shift action there is a subtle reduction in lever throw needed. This is most evident on the left shifter for the front derailleur, and I think this will be well-received by any riders with smaller hands.
It also helps achieve a faster shift. That shifter moves a front derailleur that has had its chainline moved out 2.5mm to suit more clearance for wider tyres and mud.
While Shimano expects most riders dealing with lots of mud and extreme conditions to opt for a 1×12 GRX groupset, it didn’t want to limit the capability of 2×12.
‘In the US, as gravel has become more specific Unbound sets the minimum requirement for a gravel bike,’ Lawrence told me in Bend.
This has lead to many gravel bikes being built for more extreme gravel events, and why we see a number of features often seen on mountain bikes appearing in the gravel space.
GRX 12-speed is no different, and if you opt for a 1×12 groupset, you can get the left hand shifter that is designed to work with a dropper post.
Shimano has brought the 12-speed 10-45 and 10-51 cassettes straight across from its mountain bike range, and the same applies for the chains.
This means your 12-speed road, mountain or gravel chain is one and the same – including the HyperGlide+ compatibility.
This was introduced with Shimano’s 12-speed XTR mountain bike groupset, and is found on all its 12-speed mountain bike equipment along with the 12-speed Dura Ace and Ultegra.
In short, it’s a series of shift ramps on the cassette and shaping on the chain that increases shift speed both up and down the cassette.
And arguably, it gets better under load. No doubt this plays well with the growth in the e-road and e-gravel segment as well.
My groupset uses the 31/48 dual-chainring crank set and a 105 11-36 cassette. This wider range cassette comes from the 105 line-up.
While it’s totally compatible with GRX, it doesn’t have the extra ramps of HyperGlide+, to keep it in the 105 price range.
But Lawrence confirmed it was an essential addition to 2×12 GRX. ‘We needed to look at what we could do with wider range. It needed to be something more than 11-34.
This also worked well with the new 105 with both Di2 and mechanical.’ Given the shift of gravel bikes and all-road bikes to more capability, groupsets and gear ranges need to keep up.
I have used the HyperGlide+ equipment on my mountain bike for more than four years, but I was far from disappointed in having the 11-36 cassette missing it.
I was grateful for the gear range, with the lower gear allowing a little more flexibility with cadence on steeper and looser slopes – something that is reasonably common around my home base in south-east Queensland.
Still, the 105 cassette is no light option and I’m certain that the market would adopt 11-36 in a lighter Ultegra unit with HyperGlide+.
The shifts are smooth and predictable – exactly what you would expect from Shimano shifting.
The Shadow+ design keeps the derailleur tucked out of the way and the clutch really helps with security in rough terrain, as it did on the 11-speed equipment.
While Shimano updated the calipers, the success of extra pad clearance blends into the background.
The result is brakes that are more likely to run drag-free despite challenging conditions, and Shimano’s new CL rotors play a role as well.
With a new carrier design, they will not be warping with heat. As it is, the braking was powerful and consistent across my predominantly dry test period.
I have ridden a number of nice gravel wheels, and I’m fairly pedantic about wheel systems on my mountain bikes and gravel bike.
The right tyre and rim combination really makes a difference when you need it to provide small bump compliance, grip and stability forsteering.
I believe lower and wider rims excel, with fast rolling hubs. It seems like Shimano agrees.
It released a wheelset previously with a 30mm wide, 32mm tall full-carbon rim. That same rim is now laced to its new hub set.
The rear hub can be fitted with a Microspline freehub to suit the 10-45 and 10-51 cassettes, or Shimano’s HG compatible freehub.
Being able to swap freehubs is a first for Shimano. With a 25mm internal measurement, the wheels support up to 50mm tyres, and were a perfect fit for the 40mm Pirelli rubber I have been riding.
At a little over 1,400g the wheels accelerate well while being precise thanks to a happy complement of 24 spokes front and rear.
Like any wheels with a high-quality hub, they roll fast. Shimano has stuck with cup and cone bearings in their hubs.
These spin for days but stay on top of maintenance to ensure these will be a beautiful set of wheels for years to come.
Gravel is forever growing and evolving. How you engage with it is up to you.
Shimano has developed three 12-speed groupsets to serve the needs of racers, riders and explorers.
They are all mechanical, and I am certain that electronic versions will be coming.
But the beauty of mechanical drivetrains goes hand in hand with the beauty of gravel.
Riding off-road asks you to disconnect, do away with preconceptions of acceptable grip, to leave phone range and to escape on your terms.
Shimano’s GRX groupsets can help with that, thanks to wide gear ranges and reliability.
There is nothing flashy with these groupsets, but there is a tradition of reliability and results. And from Shimano, that shouldn’t be a surprise.
Model Shimano GRX RX820
Chainring options 31/48, 38t, 40t, 42t
Cassette options 11-34, 11-36, 10-45, 10-51
Crank length options 170mm, 172.5mm, 175mm
Brake rotors 140mm, 160mm, 180mm
- You do you. From wide range 1×12, to a slightly narrower 1×12 range – or stick to a 2×12 option with a gear for every occasion
- HyperGlide+: don’t let this slip into the background, it makes for more secure shifting underload.
Every. Single. Shift
- The shifters have a refined cable pull for easier actuation
- New wheels: Shimano has nailed it with these – the rim depth and width is on point, with fast rolling hubs that have (gasp) interchangeable freehubs!