Shimano GRX 12-speed review: Mechanical shifting at its finest

While Shimano was the first of the three major groupset manufacturers to introduce gravel-specific drivetrains, its offerings had been somewhat overtaken by SRAM’s popular XPLR range in recent years with riders looking for a bigger gear range and wider-range cassettes. However, Shimano’s most recent upgrade to GRX sees more options and a 12-speed cassette, with the aim of posing a challenge to SRAM once again. It’s still not electronic – though that may be on the horizon soon – but the Shimano GRX RX820 draws on features from Shimano mountain bike groupsets which make it perform impressively well on the rougher terrain. Unlike SRAM who take a 1x-only approach, Shimano is keen to give riders options when it comes to their builds, with 1x and 2x kits that serve both the 800 and 600 levels. 

The test

I used Shimano’s 2x12 RX820 ‘undroppable’ drivetrain which Shimano says utilises the ‘best of both worlds’ offering riders 48/31T front chainrings paired with either an 11-34T or 11-36T cassette.

The setup I was testing delivered an ultra-wide gear range which offered me something for every type of terrain, from spinning on flat roads to conquering rolling hills or making my way up a long climb. The tight rear cassette meant that gear steps were subtle and small – something that was useful especially when on faster gravel rides with changeable terrain. I also had peace of mind when it came to the risk of chain drops thanks to the integrated Shadow RD+ chain stabiliser for extra security. Most existing 700c wheels can be used with the 2x12 set-up as it uses Shimano’s standard HG freehub body design. Shimano offers three crank arm lengths: 170mm, 172.5mm, 175mm, which is worth noting for those who prefer a a 165mm crank option – this is not available in the 800 series. 

Levers and ergonomics

The levers of the GRX820 don’t see any hugely radical changes compared to the previous iteration 11-speed GRX – they are slightly narrower and have a smoother finish since Shimano has altered the placement of the hydraulic hose where it attaches to the lever, reducing the bump that used to slightly protrude on the old levers. Shimano says that the redesigned hoods should help reduce pressure points and suit flared handlebars – something that is regularly seen on gravel bikes. Another change is to the brake lever material. Shimano uses wet-weather grip tech from its fishing rods and the ridged hood texture, according to the brand, aims to provide comfort for riders with and without gloves.

As a rider with smaller hands, I find that the GRX820 levers stand out for their size when compared to other Shimano models. Against the Ultegra Di2 levers on my road bike, for example, the GRX levers feel bigger and more bulbous and I’d like to see Shimano slim them down. I found the rubber hoods to be grippy and comfortable, however, and the ergonomic shape of the shifters makes braking on the hoods easy and controllable, while the flick at the end of the blade allows you to hook fingers around the brake when in the drops. When riding out of the saddle, there’s plenty of clearance underneath the hoods to get a really good grip, too. I didn’t suffer from any pain or blistering on my hands even on long, bumpy gravel rides, but I did feel some muscular fatigue after a while due to the bigger size of the shifters.

Braking

Shimano hasn’t given the latest GRX any huge changes when it comes to the callipers, but the brand has added 10% more rotor clearance with the aim of bringing noise down. The bleed port has also been moved outside of the calliper body for easier access. Shimano uses ‘Servowave’ tech which should mean that less movement is needed in order to bring the pad to the rotor, so a higher braking force can be achieved with less effort.

I found the braking to be sharp and easy to modulate which gave me plenty of confidence on technical sections as I knew I could rely on stopping power at short notice if I needed it. Even during wet weather, the brakes worked equally well and I didn’t have any issues with noise or rubbing.

Shifting

It’s fair to say that Shimano’s GRX 12-speed groupset is a reminder of the value of mechanical shifting. While the market is somewhat dominated by electronic groupsets on high-end modern bikes, which inevitably has elevated performance, there’s a lot to be said for the simplicity, lower cost and ease of use of mechanical shifting. It’s likely that a Di2 version of Shimano’s GRX 12-speed is in the works, but this certainly shouldn’t make the mechanical option redundant as it does a job good enough for the majority of us.

I found the shifting on the RX820 group to be reliable, crisp and responsive, even when under heavy load. Gravel riding in the British winter can be especially brutal on a rider’s components, but the GRX never faltered even when the terrain got extreme. Shimano's Shadow RD+ chain stabiliser is engaged using a lever on the rear derailleur and this helps to keep the chain tight when things get rough and ensures that the drivetrain is especially quiet. I found that the inner shift paddle is responsive with only a small hand movement needed, though the movement to change up the cassette and to change chainrings at the front is still bigger than you’d get on an electronic groupset. While the shifting is marginally slower and not quite as effortless as when using electronic gears, not having to worry about batteries or charging the gears certainly makes heading out on a ride a lot simpler.

Verdict

There’s nothing particularly glamorous about the new Shimano GRX-12 Speed groupset, but in some ways this is what makes it so good. It’s a purely functional piece of kit that is easy to set-up, use and maintain, with none of the complications that come with electronic groupsets. The braking power and shifting performance is hard to fault and is a good argument for why mechanical shifting is certainly not dead. It might not be quite as fast or as customisable as electronic shifting, but the RX820 will do the job and more for the majority of us.

The double-chainring option I used is described by Shimano as the ‘all-road’ option and I would agree that its versatility goes a long way to justify the price point (RRP of the 2x Shimano GRX RX820 groupset is £1239). If you are looking for a groupset to go on one bike to do it all with the option to just switch wheels or tyres depending on what type of riding you’re doing, this is a good and easy choice. There’s no power meter option currently from Shimano and those who are doing the most serious gravel racing may miss the speed of electronic gears, but overall, the RX820’s flawless shifting, simplicty and braking make it a perfect groupset for the masses.