A new prototype SRAM 13 speed AXS XPLR group using SRAM's Transmission with T-Type rear derailleur is spotted at Unbound Gravel - are new SRAM 13 speed XPLR groups for drop bar cyclocross and gravel bikes on the horizon? It appears so.
It's possible, of course, that such components never reach market. Plenty of ideas don't make it past the testing phase. However, pros riding unreleased equipment in such a high-stakes competitive event nearly always leads to a future public release, so it's a safe bet that the SRAM AXS XPLR line will eventually come to market in a 13 speed version.
What did we learn?
Unbound Gravel, one of the hardest events on equipment anywhere, is a great testing ground. Keegan Swenson showed a Santa Cruz Stigmata (more on that later) kitted out with some previously unseen gear, including a 13 speed cassette, and "Transmission" T-Type rear derailleur, previously only found on SRAM's MTB groups.
In SRAM-speak, "AXS" (say access) means wireless shifting, while "XPLR" (say explore) is their line for drop bar bikes ridden in the dirt - think cyclocross, gravel, and bikepacking, with larger cassettes and lower gears. So a new AXS XPLR Transmission group ("Red", presumably) would be wireless shifting, wide range drivetrain, with Transmission shifting, designed for drop bar use.
Notably, Keegan's bike has 13 cassette cogs - even though SRAM just released a new, updated Red road group with 12 in just the last couple months. So what's going on here? Well, it seems we got an early preview of what SRAM's gravel and cyclocross focused groups might look like in the future - wireless shifting, 1x single chainrings, Transmission T-Type rear derailleurs, and yes, 13 cogs.
Shimano GRX Di2 1x 12 speed is MIA, for now
Another drivetrain that recently got another cog is Shimano's GRX, which recently moved from 11 speed to 12. GRX had previously been stuck on 11, while all of Shimano's other high end road and MTB lines had long since moved to 12 cogs.
Curiously, Shimano did not release a 1x single chainring Di2 version of their new GRX 12 speed group - what's been released (thus far) is double chainrings only. This fueled some gossip that Shimano might skip 12 and go right to 13, perhaps driven by recent patent applications - Shimano has submitted patents for a 13 speed, fully wireless line of components. While patents don't directly predict future product releases, moving to 13 cogs seems inevitable.
In a somewhat strange twist of fate, Shimano actually had a Saint group in which the rear derailleur attached directly to the axle 15 years ago. While not identical to the way SRAM's UDH Transmission works, Shimano was certainly way ahead of the game in trying to create stronger, stiffer rear derailleur mounting - at least on downhill and free ride bikes.
What about Campagnolo 13 speed?
Campagnolo fans will no doubt be thinking "Campy already has 13 speed!" and that's true. The 13 speed Campagnolo Ekar groups beat SRAM and Shimano to market by quite a while. The signature feature of Ekar is a single chainring design (no double chainring or front derailleur version is offered) with a wide-range, 13 speed cassette.
Ekar has been generally well received, but is orders of magnitude less popular than SRAM and Shimano components. Part of that is there is almost no market for Campagnolo-equipped bikes at your local bike shop. What's out there is almost always a custom build. Ekar is also mechanical shifting only; while Campagnolo does offer electronic shifting on par with SRAM and Shimano, it's not offered on Ekar.
Why does Transmission even matter?
One of the key selling points is simplified setup. Because the placement of the axle, rear derailleur, and cassette are extremely precise, all the setup can occur via the SRAM mobile app. In fact, the derailleur doesn't even have limit screws on it!
In cyclocross in particular, heavy mud can be par for the course. In these conditions, it's common to see derailleurs heavily damaged, or even ripped completely off the frame. A compelling argument can be made that UDH / Transmission / T-type components might better stand up to the heavy mud encountered in cyclocross. It's possible we could see cyclocross pro teams that are sponsored by SRAM riding a 13 speed, 1x, Transmission as early as this Fall.
What does this mean for future frame design?
The SRAM Transmission groups require a dedicated frame that uses SRAM's UDH (universal derailleur hanger) design, which accepts the "T-Type" rear derailleur. While they are increasing in popularity, especially in the MTB space, this design has been less common in the gravel and cyclocross space. Some of the frame brands that are using the UDH design include the most recent revisions of the Santa Cruz Stigmata and Canyon Grail, but you won't find it on a Specialized Crux, Trek Boone, or Cannondale SuperSix EVO - at least at the present time.
If a new SRAM AXS XPLR group does turn out to be the Transmission type, many frames on the market won't be readily upgradeable - which in turn, can drive new bike sales, but also means upgrading wouldn't be possible at all for older frames that aren't UDH.