Brand new 12-speed Shimano GRX groupset breaks cover at Unbound Gravel

A brand new 12-speed Shimano GRX gravel groupset has broken cover at Unbound Gravel. 

Taylor Lideen, the Shimano-sponsored Arizonan who is riding the 352-mile 'XL' route has been spotted with the all-new groupset aboard his Pivot Vault gravel bike. 

First noticed by Ben Delaney and shared on his The Ride YouTube channel, the groupset looks largely similar to the current GRX groupset at face value, but on closer inspection, it becomes clear that this is indeed an all-new version of Shimano's gravel groupset. 

The most significant difference is the upgrade to a 12-speed cassette. Current iterations of GRX, of which there are three, include a 10-speed option known as RX-400 and two 11-speed options comprising mechanical RX-600 and electronic RX-800 Di2. 

The move to 12-speed was widely predicted - if not expected - for the new GRX, given that options within both Shimano's road and mountain bike ranges had made the same change, but there were no clues as to when it would come. 

Interestingly, according to Delaney, Lideen's bike is actually using an XTR cassette rather than a GRX-specific version. This proves an element of cross-compatibility across the brand's gravel and mountain bike groupsets, as has been possible with existing GRX. The cassette in question is a 10-45T. The existing 11-speed GRX had a maximum cassette size of 11-42, so this confirms new Shimano GRX will be able to handle wider cassettes than before, even if it doesn't confirm the maximum available capacity. 

The new GRX groupset shown on Lideen's bike is mechanical, rather than the more premium Di2 electronic shifting technology. This is almost certainly due to the arduous 352-mile task ahead and the increased reliability offered by mechanical shifting under such circumstances, rather than any omission of an electronic option within the new GRX range. We'd be very surprised if the latter was actually the case. 

Positively, this seems to confirm that the new Shimano GRX won't exclusively be an electronic groupset, such is the way that the brand's Dura-Ace, Ultegra and 105 road groupsets have gone in recent years. 

The rear derailleur itself has seen a fairly significant aesthetic update, as shown in the picture above. It has borrowed design cues from more recent models on both road and mountain bike sides of Shimano's coin. It appears to have made the switch to direct mount, bringing it much closer to the bottom of Lideen's chainstay than seen on Vermeulen's Enve MOG. 

The top pulley wheel appears much larger too, although this could simply be an illusion of the photos we have and their respective positions hidden behind the rest of the cage. Regardless, the cage itself is evidently much shorter, with the overall shape of the mech appearing smaller, therefore could feasibly be both stiffer and lighter. 

In Delaney's video, which we've embedded below, he also points out a newly designed clutch, which features a larger switch more alike those found on Shimano's mech.

From the few photos we have alongside Delaney's sleuthing, we can't spot any differences in the shifters. Aside from the necessary internal changes, it appears Shimano has stuck with the same visual formula.

The same can be said for the chainset too. Lideen's single chainring is marked up with 'Shimano GRX 12S 42T'. The fact that it is a single chainring means there's no definitive confirmation at this point that GRX will remain 2x compatible, but it would be a huge surprise if Shimano did make it 1x only. The inclusion of a shift paddle on the left lever helps to confirm this theory. 

It appears that the new Shimano GRX also has newly designed brakes. They have at least borrowed the aesthetic DNA from Shimano's Dura-Ace and Ultegra groupsets if not functionality too. 

They appear to still use the same pads, but the bleed port has been moved to the outer face for easier access (as was introduced with the aforementioned road groups). They have also made the switch to a hex-key brake pad retention pin, instead of the flat-head screwdriver which was fairly easily damaged. 

In terms of an official launch date and availability, your guess is as good as ours at this point. 

The groupset certainly looks to be in a finished production quality state, suggesting it could be impending, but with Shimano having struggled quite significantly from the industry's supply chain issues in recent years, such things aren't as straightforward or predictable as they once were!