Shimano's GRX gravel groupset finally goes 12-speed

Shimano GRX was touted famously as being the first gravel-specific groupset when it launched back in 2019. While its release was innovative at the time, GRX has remained essentially unchanged since.

Shimano has finally released a new version of its GRX gravel groupset, although the update is more of an evolution than a complete redesign. The new Shimano GRX RX820 is now 12-speed and the new derailleurs are compatible with larger cassettes for increased range too. Shimano has also updated the GRX RX610 series to offer lower tier 12-speed cranks and shifters, as well as giving their GRX gravel bike wheels new hubs for faster engagement and 12-speed compatibility. The Japanese brand has also announced a 12-speed version of its 105 groupset.

Despite being four years old now, Shimano's original GRX is still an excellent groupset. When compared to SRAM's XPLR range and Campagnolo's Ekar gravel groupsets though, there a notable weakness when it comes to gear range and spread. 

The new derailleur is now 12-speed and the medium caged mech is compatible with 10-45t cassettes, offering a significantly wider range than the older GRX 11-42t option. Although on paper its only a couple of teeth different either side, its actually a significant jump in gear range from 382 percent to 450 percent.

If that's not enough gear range, the GRX RX822-GSG long cage derailleur is compatible with 10-51T which should be enough to tackle the steepest climbs. The derailleur cages can be changed or replaced as well, so if you want more gearing for a bikepacking adventure, you can just switch the cage rather than buying a whole new derailleur.

For GRX RX820, Shimano cross-pollinated its existing XT 10-45t and Deore M6100 10-51t 12-speed MTB cassettes which use Shimano's MicroSpline freehub standard – which was released alongside Shimano's first 12-speed groupset. By increasing the amount of splines to 23, Shimano says it gives a more positive engagement between hub and cassette and reduces the risk of deformation and gouging of the forged aluminum freehub body.

The rear derailleurs still feature Shimano's Shadow RD+ chain stabilizer to keep the chain tensioned over rough terrain, which has proven very reliable from our past experiences.

Interestingly, despite the originally GRX release including a Di2 version of the groupset and SRAM current campaign to electrify everything they sell, there isn't a Di2 version of the GRX RX820 groupset included in this release.

Shimano recently released a 105 level Di2 road groupset, so we speculate there will be an electronic GRX RX825 Di2 option in the future – although there is no evidence as to if or when that is likely to happen.

Make it a double

Although Shimano have greatly increased the range of their 1x groupset, they haven't turned their backs on 2x. The GRX RX820 12-speed groupset is still available in a 48-31t double chainset configuration and also sees an increase in gear range. The 2x 12-speed derailleur capacity has been increased to 36t, with the option of either a 11-34t or a 11-36t HG cassette. 

The front derailleur uses Shimano's Toggle link construction giving more cable routing options and has wider tire clearance (chainline +2.5mm vs. conventional road FD) to make space for larger knobbly gravel tires.

Updated levers

Visually its hard to determine whats actually been changed, but Shimano says they have updated the ergonomics of the new 12-speed levers. The shape is said to be designed for all-day comfort when using flared drop bars and reduce pressure by increasing surface area without any additional lever bulk.

The levers will still be available in 1x, 2x, and 1x with dropper lever configurations.

Microspline for gravel

Shimano released a new GRX RX870 carbon wheelset last year and were a bit vague as to what freehub standards would be available. The brand has now confirmed a RX880 series carbon gravel wheelset to compliment their new 12-speed drivetrains. 

While the wheels appear to use the same 32mm carbon rim with a 25mm inner rim diameter as the RX870, but has an updated MicroSpline hub. The hub borrows technology from Shimano top spec Dura-Ace wheels, featuring a revamped Direct Engagement hub design that can be easily converted between MicroSpline and HG L2 12-speed freehub bodies (not compatible with 11-speed HG cassettes).

The wheels only come in 700c and are claimed to be 64g lighter than the RX870 version, with a quoted weight of 1394 grams (MicroSpline hub).

Shimano GRX RX820 groupset pricing and specifications