A 12-speed Shimano GRX gravel groupset is now available at Unbound Gravel.

Shimano-sponsored Arizonan Taylor Rideen, riding the 352-mile "XL" route, was spotted with a brand new groupset on his Pivot Vault gravel bike.

First spotted by Ben Delaney and shared on his YouTube channel "The Ride," the groupset looks almost identical to the current GRX groupset at face value, but closer inspection reveals that this is indeed a Shimano groupset for gravel that this is indeed a completely new version of Shimano's gravel groupset.

The most significant difference is the upgrade to a 12-speed cassette. There are three current GRXs, a 10-speed option called the RX-400 and two 11-speed options, the mechanical RX-600 and the electronic RX-800 Di2.

The move to 12-speed was widely predicted, if not anticipated, for the new GRXs, as both Shimano's road and mountain bike series options had the same change.

Interestingly, according to Delaney, the Reddin bikes are not GRX-specific versions, but actually use XTR cassettes. This proves an element of compatibility across the brand's gravel and mountain bike groupset, as was possible with the existing GRX. The cassette in question is a 10-45T; the maximum cassette size for the existing 11-speed GRX was 11-42, confirming that the new Shimano GRX can accommodate wider cassettes than before, even if the maximum available capacity cannot be confirmed.

The new GRX groupset on the Rideen bikes is mechanical, rather than the more premium Di2 electronic shifting technology. This is almost certainly not due to the lack of electronic options in the new GRX series, but rather to the grueling 352-mile task ahead and the increased reliability that mechanical shifting offers under such conditions. If it is the latter, I would be very surprised.

On a positive note, it seems to confirm that the new Shimano GRX will not be the only electronically controlled groupset like recent Dura-Ace, Ultegra, and 105 road offerings.

The rear derailleur itself has undergone a fairly significant aesthetic update, as seen in the photo above. It takes design cues from recent Shimano models on both road and mountain bikes. The direct mount has been changed to a direct mount, much closer to the lower part of the chainstay on the redeemer, as seen on Vermeulen's Enve MOG.

The top pulley wheels also appear much larger, but this may simply be an illusion due to the photos we have and their respective positions hidden behind the cage. In any case, the cage itself is quite short and the overall shape of the mechanism appears small.

In Delaney's video, embedded below, he also points out a newly designed clutch that features larger switches, similar to those found on Shimano mechs.

From the few photos that accompany Delaney's prodding, no differences can be seen in the shifter. Aside from the necessary internal changes, Shimano seems to have stuck to the same visual formula.

The same can be said for the chainsets. The single chainring on the Reddin is marked "Shimano GRX 12S 42T. The single chainring means that there is currently no definitive proof that the GRX will remain 2x compatible, but it would be a big surprise if Shimano went 1x only. The fact that the left lever has shift paddles also supports this theory.

The new Shimano GRX also appears to have newly designed brakes. Functionality aside, it at least borrows some aesthetic DNA from Shimano's Dura-Ace and Ultegra.

They still appear to use the same pads, but the bleed port has been moved to the outside face for easier access (as introduced in the load group mentioned above). Also, the hex-key brake pad retention pins have been replaced by hex-key brake pad retention pins instead of flathead screwdrivers, which were prone to breakage.

As for an official release date and availability, your guess is as good as mine at this point. [However, this is not as simple or predictable as it used to be, as Shimano has struggled quite a bit in recent years with supply chain issues in the industry.