Shimano has unveiled the GRX RX820 12-speed mechanical groupset, which updates the gravel groupset's 1x offerings closer to a mountain bike gear range.  The 12-speed groupsets are available in three configurations - two of them built on a 1x setup, and one for 2x - each catering to varied gravel riding styles. Simultaneously, Shimano has also presented an upgraded 600-series 12-speed variant, delivering extended gear capabilities at a more affordable price.

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The new 12-speed GRX is a much-anticipated update to Shimano's gravel shifting range, bringing its gravel groupset that has been predominantly best suited for 2x setups in line with competitors' - mainly SRAM's - offerings. After its pre-launch runs in the wild at multiple gravel races, we've now got all the official details of the 12-speed version of the Japanese component giant's gravel-specific components.

The largest change is obviously the addition of another cog to the setup, but simultaneously Shimano has also made the GRX 820-series have the option to run with a 10T smallest sprocket. This has been allowed by adopting the Microspline-free body and redesigning the rear derailleur. 

Although the changes from the 11-speed GRX are visually minimal, the 12-speed GRX comes with revamped shift and brake levers which Shimano says enhance control through pressure point reduction and increased surface area. They have also been optimised for flared drop bars commonly used by gravel riders, according to the brand. 

In conjunction with the 12-speed GRX, Shimano has also introduced a 12-speed 105 groupset to its lineup, and a set of new gravel wheels. You can read all about the 12-speed mechanical 105 on our roadie sister-site here. 

As mentioned before, the new 12-speed GRX mechanical comes in three configurations, and we'll have a look at what each is about next... 

Shimano GRX 12spd chainring, by Shimano

Shimano GRX 1x12 Unbeatable

The first 1x option in the range is dubbed Unbeatable, and according to Shimano, retains the smooth and reliable shifting of its 11-speed predecessor while introducing a broader gear range and an extra cog to the cassette. Shimano says this setup is designed for riders chasing personal bests and competitive races and combines a 10-45 cassette with a 40- or 42-tooth chainring. According to Shimano, this adaptation simplifies maintaining an optimal cadence in pack riding and intense racing scenarios.

The setup incorporates the RD-RX822-GS medium cage rear derailleur, equipped with the integrated Shadow RD+ chain stabiliser (aka clutch) for smoother, quieter shifts and chain security on rugged terrains.

Shimano GRX 12spd rear mech, by Shimano

Shimano GRX 1x12 Unstoppable

The Unstoppable also utilises the simplicity of a 1x set-up but also ups the game in terms of gearing, and Shimano says it's targeted for lengthier adventures and arduous climbs. The Unstoppable configuration can be run as a 10-51T cassette paired with a 40- or 42-tooth chainring. 

To get those extra gears in, the Unstoppable uses the RD-RX822-GSG long-cage rear derailleur, combined with the very same Shadow RD+ chain stabiliser. Here it's worth noting that a novel feature of this GRX generation is the capability to interchange or replace only the derailleur cage across the 1x12 options, which adds adaptability without necessitating the replacement of the entire derailleur, not to mention it's cheaper, too. 

As you might've guessed from the 10T smallest cassette sprocket, the Unstoppable setup also utilises the Micro Spline mountain bike hub technology, ensuring durability and reduced cog wear over time.

Shimano GRX 12spd 2x, by Shimano

Shimano GRX 2x12 Undroppable

Shimano's GRX lineup has always offered a 2x option and it's not changing with this launch. Undroppable is the only 2x option in the new 12-speed range and caters to riders seeking the most versatile setup. This drivetrain pairs gravel-optimised 48/31T front chainrings with an 11-34T or 11-36T cassette. Being a 2x12 setup, it delivers the widest gear range in the lineup, suitable for comfortable cruising, tackling challenging dirt roads, or confronting steep backcountry climbs.

The 2x GRX features an FD-RX820 front derailleur with toggle link construction which according to Shimano offers varied cable routing options, wider tyre clearance, and precise mechanical front and rear shifting. At the rear, the mech gets the same Shadow RD+ chain stabiliser as the other setups to enhance drivetrain stability over uneven terrains.

Shimano GRX 12spd shifters, by Shimano

Updated GRX 610-series

Addressing the needs of budget-conscious gravel cyclists and diversifying price options for complete gravel bikes, Shimano also introduced updates to its lower-tier 600-series cranks and shift levers for both 1x12 and 2x12 setups. The updates to these slightly heavier components draw from the technological advancements of the 11-speed 800 series GRX components, and the key updates include textured hoods and an anti-slip brake lever coating, enhancing control on challenging terrains. 

The RX610 2x12 crankset boasts 46/30 chainrings and is available in crank arm lengths of 165 mm, 170 mm, 172.5 mm, and 175 mm. Likewise, the RX610 1x12 crankset offers the same length options and introduces the addition of steel 38T and 40T chainring variants, compatible with either a 10-45T or 10-51T cassette. Worth mentioning here that interestingly, if you're wanting to run 165mm cranks then the 600-series is your only option, as Shimano starts the 800-series from 170mm. 

Shimano GRX 12spd on bike, by Shimano

Shimano 12-speed pricing

Obviously, you are interested in what all of this new 12-speed GRX stuff is going to cost. 

The total price for a GRX 820 1x12 and 2x12 groupsets comes to £1,349. A full lower-tier 12x2 RX610 groupset would come to £1,064. 

820-series Shifter and Disc Brake Set

RX820 GRX 12-speed STI bled with flat-mount calliper, right front - £350

RX820 GRX 2-speed STI bled with flat-mount calliper, left rear - £350

RX820-LA GRX dropper post lever bled with BR-RX820 calliper, left rear - £350

RX820 GRX hydraulic disc brake lever bled with BR-RX820 caliper, left rear - £330

Brakes:    

RT-CL800 disc rotor £55

SMRT70 disc rotor £30

820-series derailleurs: 

The rear derailleurs RD-RX820 (max 36T for double), RD-RX822 (max 51T) cost £120

The FD-RX820 GRX braze-on front mech is £56

820-series chainsets

The single chainsets are available with 170mm, 172.5mm or 175mm cranks and 40 or 42T chainrings and each sets you back £230

The doubles come with the same three crank lengths and 48/31 chainrings and retail for the same, £230.

The 10-45 and 10-51 cassette are both £160 and the 11-36 retails for £85.

Shimano GRX 12spd cassette, by Shimano

Chain options 

There are two chain options, the CNM8100 (£50) with Hyperglide tech and CNM7100 (£35).

RX610 series components

Shifter and Disc Brake Set

RX610 GRX 2-speed STI shifter with flat-mount caliper, left - £280

RX610 GRX 2-speed STI shifter with flat-mount caliper, right - £280

RX610 GRX hydraulic disc brake lever bled with BR-RX400 caliper, left rear - £260

Chainset

FC-RX610 GRX chainset 38T, 40T single or 46 / 30 double with 165mm, 170mm, 172.5mm or 175mm crank: £150

Shimano GRX 12spd wheels, by Shimano

RX880 Carbon Gravel Wheels

Shimano hasn't just created a new 12-speed GRX lineup, but also a wheelset to complement them all. The new RX880 carbon gravel wheels have been designed to excel on demanding dirt roads and weigh 64 grams less per pair than their predecessors. They boast a shallow 32mm rim height for quicker acceleration and climbing and are tubeless-ready. The 25 mm inner rim width accommodates tyre sizes from 32mm to 50mm.

Shimano has also notched up the compatibility of the RX880 wheels with a redesigned Direct Engagement hub, borrowed from the brand's premium Dura-Ace wheels. This hub transitions between Micro Spline and HG+ 12-speed freehub bodies. The Micro Spline wheelset weighs 1,394g and the HG+ should tip the scalses at 1,397g.

The wheels retail for £580 (front) and £720 (rear). 

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