New Shimano GRX switches to 12

Shimano introduces new Unbeatable, Unstoppable and Undroppable versions of its gravel groupset

This competition is now closed

By Liam Cahill

Published: August 31, 2023 at 5:00 pm

Shimano has officially launched its GRX RX820 gravel bike groupset. It’s an all-mechanical 12-speed affair (for now) and features far wider gearing options than before, closing the gap to rivals SRAM and Campagnolo.

The new GRX groupset is only currently available in a mechanical version, with no word on Di2 at the time of launch, although we’d expect that to change in the future.

The second-tier GRX RX610 also moves to 12-speed, maintains 2x and 1x options and gets trickle-down technology from the original 800 series GRX.

Within both GRX tiers, there are three sub-families; Unbeatable, Undroppable and Unstoppable. These are designed to give distinct identities to the three available setups (1x for gravel racing, 2x for all-round gravel riding and a 1x mullet drivetrain) within each tier.

Shimano has also updated its range of gravel wheels. The carbon RX880 uses a 32mm-deep, hooked rim with a 25mm internal width. Shimano says the tubeless-ready wheels are suitable for gravel tyres from 32mm to 50mm wide.

Here we’ll concentrate on all of the tech details, but you can also read the verdict on how it performs in our full Shimano GRX RX820 review. We’ve also covered the release of Shimano’s new 105 mechanical road groupset.

The ergonomics of the shifters have been updated to better match flared bars, which are commonly seen specced on gravel bikes. The signature ridges on the top face of the shifters have been retained and the pattern hasn’t changed. These are designed to aid grip in wet or muddy conditions.

Shimano has also looked to improve the contact angle of the shifter body where it meets the bar. The brand says this change increases the surface area on which hand pressure is applied, reducing the likelihood of hand pain.

In an interesting collision of the cycling and fishing worlds, Shimano has borrowed tech developed for its fishing rods and applied it to the brake levers.

The material, which feels a little more coarse than you’d usually expect, was developed to increase grip on a rod with wet hands. Because gravel rides can take in a variety of conditions, Shimano hopes the new material will improve confidence in adverse weather.

Shimano has significantly expanded its GRX gearing options for both 1x and 2x options.

1x drivetrains now have 10-46t and 10-51t cassette options. 2x drivetrains are offered with the standard 11-34t and 11-36t cassette options.

The previous widest-range 1x cassette option was 11-42t. This fell well short of SRAM’s top- and low-end gears.

For instance, SRAM used a much wider 10-44t cassette in its XPLR range, and also offered the ability to use its 10-51 and 10-52t MTB cassettes.

The new GRX groupsets share cassettes with Shimano’s existing mountain bike drivetrains. This includes the move to a Micro Spline freehub for 10t cassettes.

This differs from Shimano’s 12-speed road bike groupsets, which use the HG L2 freehub standard.

A surprising addition to the new groupsets is a set of new names.

Shimano generally relies on consistent product code conventions to denote variations within a product range, so this move was unexpected.

We now have Unbeatable, Undroppable and Unstoppable.

Broadly speaking, this covers a 1x drivetrain for fast gravel riding or gravel racing (Unbeatable), a 2x drivetrain for all-round gravel riding (Undroppable) and a 1x drivetrain with wide-range mullet gearing (Unstoppable).

GRX RX820 is the name given to Shimano’s 1x gravel bike groupset that’s designed for gravel racing.

Pairing a 10-45t cassette with a 1x 40t or 42t chainring, Shimano claims riders who “love pushing for personal bests or duking it out at the sharp end of a race, will appreciate the gear steps” of GRX Unbeatable.

While the 1x crankset hasn’t changed beyond a slight narrowing of the chainring profile to accommodate a narrower 12-speed chain, the cassette has grown at both ends.

This move to a 10-45t cassette makes Shimano’s Unbeatable gearing slightly wider than SRAM’s XPLR 10-44t cassette.

Just as with the outgoing groupset, Shimano is promising smooth and reliable shifting from Unbeatable. It is also said to be quieter and more secure over rough terrain, thanks to the new Shadow RD+ chain stabiliser.

We asked Shimano if it was tempted to use a 10t cog here, which would have enabled it to reduce chainring size further. However, Shimano’s Dave Lawrence said 2x riders aren’t as concerned with total range, preferring a closely spaced cassette, the efficiency of an 11t cog and reverse compatibility with existing HG freehub wheelsets.

The use of a 2x crankset and cassette ratios that we commonly see on road bikes confirms Shimano still holds a soft spot for a double-chainring setup.

While 1x gravel bike groupsets have grown in popularity, they require the use of a wide-range cassette to provide the same range as a 2x drivetrain. This results in larger gaps between gears, which can sometimes force an awkward change in cadence.

The RX820 rear derailleur features the shortest cage of the RX820 range, allowing for a maximum cog size of 36t. It does not have the built-in cage interchangeability of the 1x-specific RX822-GS and RX822-SGS derailleurs.

The RX820 rear derailleur does, however, feature the Shadow RD+ clutch mechanism.

Shimano has designed a new front derailleur which, it claims, allows for wider tyre clearances. The chainline measures +2.5mm versus a standard road bike front derailleur.

GRX RX820 Unstoppable is the first true mullet gravel drivetrain Shimano has offered, pairing the new RX822-SGS rear derailleur with an XT M8100 10-51t cassette.

The new derailleur features an updated clutch mechanism, which Shimano says is “optimised for use with the 10-51t cassette”.

Mullet drivetrain setups provide gearing suitable for both faster flat sections and steep, technical climbs by using wide-range mountain bike rear derailleurs and cassettes. These are paired with drop-bar shifters.

SRAM groupsets were relatively easy to set up in this way, but Shimano used different pull ratios for its MTB and gravel derailleurs, so fitting a Shimano MTB rear derailleur to Shimano drop–bar shifters wasn’t possible.

However, earlier this summer SRAM arguably legitimised mullet setups through the launch of its Apex Eagle groupset.

To see Shimano respond with its own official mullet setup is great news for user choice.

Adding noteworthy customisability to the groupset, Shimano says the derailleur cage is interchangeable with the Unbeatable groupset.

This means you could swap between Unbeatable and Unstoppable gearing on the same bike by changing the derailleur cage, cassette and chain.

With the RX820-LA, Shimano continues to offer a dropper post lever integrated into the left-hand shifter for 1x setups.

However, Shimano says the cable pull has been modified to suit a greater number of dropper posts.

Shimano’s GRX gravel groupset range continues to be two-tiered and a more affordable RX610 groupset has also been announced, incorporating 12-speed gearing and trickle-down tech from the original GRX800 series.

The groupset comes in both 1x and 2x guises, with the former offering a 38T or 40T chainring and compatibility with 10-45T or 10-51T M7100 cassettes.

The RX610 2x groupset, using 46/30 chainrings, provides slightly reduced range compared to RX810.

As with RX810, the cassette options start with an 11T cog with 34 or 36T top-end offerings.

Servo Wave, Shimano’s progressive brake actuation, is dropped, as is the lever optimisation for flared bars.

There is also no shifter with an integrated dropper post lever at the RX610 level.

But while these features are absent at the RX610 level, the groupset is still available in Unbeatable, Unstoppable and Undroppable forms, albeit with gear ratios that trend lower than RX810.

What are three new groupsets if you don’t launch shiny wheels to match?

Shimano has brought its gravel wheel offering up to date, though the changes amount to a hub design, which enabless either an HG+ or Micro Spline freehub to be fitted.

Should you be familiar with the outgoing GRX carbon wheelset, with its 25mm internal rim width and 32mm depth, you’ll notice only that the large GRX logos have been removed.

The RX880 wheels are still tubeless-ready, with a hooked rim and a recommended tyre size of 32-50mm.

Shimano claims the Micro Spline freehub wheelset weighs 1,394g, while the HG+ version is slightly heavier at a claimed 1,397g.

Road and gravel presenter

Liam Cahill is the road and gravel presenter for the BikeRadar YouTube channel. Liam has been racing road and cyclocross since his teens, and riding for as long as he can remember. With a national 24hr time trial champion for an uncle, there are racing genetics in his family. However, Liam has inherited none of them, boasting the South West’s largest collection of Cat 3 2nd place finishes. Before joining BikeRadar, Liam was a tech writer and presenter at road.cc, where he published hundreds of reviews. From budget bikes to the most expensive upgrades, he’s tested it all. When not presenting, you’ll find him contributing reviews to BikeRadar.com, nattering on the BikeRadar Podcast and listening to Taylor Swift whenever possible.

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