Unbound Gravel race weekend is here. Thousands of amateur and professional racers are descending upon Emporia, Kansas, in the middle of nowhere America, for the world’s premier gravel race.
As race day approaches on Saturday, June 1, riders are hitting the course for shakeout and recon rides. In addition to pondering tire choices, warming up the legs and testing their gear options, some riders are acquainting themselves with yet-to-be released equipment that will be raced for the very first time here across the 200 miles of Tallgrass Prairie and Flint Hills.
For the past few years, as the competition and prestige at Unbound have grown, the race has also become a launching pad and proving ground for cutting-edge gravel tech. For the eagle-eyed among us, there’s a good chance you may spot something unusual.
We got lucky early on, when we spotted this potentially new SRAM gravel drivetrain on a group ride this morning.
What caught my eye was the beefy SRAM transmission-style rear derailleur. Launched as part of its Eagle mountain bike line in 2023, the SRAM Transmission is a 1x 12-speed wireless electronic drivetrain that is not only free of any wires, it also functions without a derailleur hanger, limit screws or B-tension adjustments.
It’s designed to be mounted directly to the frame around the wheel axle, in place of where a derailleur hanger would be. It does requires a frameset with the Universal Derailleur Hanger (UDH) interface, but luckily the adoption rate of this standard is growing widely among frame manufacturers.
Since its launch, the system has garnered favorable reviews for its robustness and simplicity with plenty of videos circling around the internet of people kicking and jumping on the derailleur without having an impact.
Like the rest of SRAM’s wireless groupsets, the wireless derailleur is powered with the same AXS batteries we’ve become familiar with. On the handlebars we spotted the same shifters that were revealed as part of the American manufacturer’s SRAM Red AXS road groupset just a few weeks ago, and the brake calipers also appear to taken from this groupset —both of which impressed our reviewers here at Cycling Weekly.
“The braking performance is now genuinely best in class, which is truly impressive, and shift quality is slightly better than the outgoing Red,” wrote Joe Baker.
However, this new gravel groupset sports something the road groupset doesn’t have, Transmission aside, and that is a 13th cog. I got close enough to count the rings of the cassette myself, and sure enough, there are 13 cogs in the back. Until now, Campagnolo was the only manufacturer to make use of 13-speed cassettes in its gravel groupsets. SRAM introduced 12-speed drivetrains in its mountain bike line first in 2016 and carried it over to road and gravel in 2019. Shimano has been playing catch-up in the gravel space, introducing 12-speed mechanical GRX just last year and the electronic 12-speed GRX only last week.
As of yet, it is unknown when SRAM will make the 13-speed SRAM Red AXS XPLR available commercially, though it’s likely that we’ll see it by the end of the summer.
