By our count, there are four big trends in wheel technology that are relevant to cyclocross and gravel cyclists: disc brakes; tubeless; wide rims; and thru axles.
Zipp Speed Weaponry has already embraced disc brakes, with the 303 Firecrest clincher and tubular wheels released in 2013, and the 202 Firecrest clincher wheelset we first saw last June.
As of today, the Indianapolis-based SRAM company embraces thru axles, and has updated the disc brake versions of its 202 Firecrest clincher and 303 Firecrest clincher and tubular carbon wheels with new thru axle hubs that it calls the 77 (front) and 177 (rear).
Going Wide with XD Driver Option
The more curious option offered by Zipp on the new Zipp 303 tubular and clincher and Zipp 202 clincher wheelsets is the XD Driver option. The XD freehub body, which accepts (requires) a 10-42t cassette, will offer wide-range gearing for the single ring gravel and cyclocross racer. Such a wide-range SRAM XD cassette requires an XX1 or XO1 mountain bike rear derailleur, and the problem is right now, shifters compatible with these derailleurs are only available for flat bars.
SRAM admits that to take advantage of this option, one would have to build sort of a frankenbike (which can win a National Championship), and use these carbon road wheels on a mountain bike or flat bar road or cyclocross bike. Pairing the wheels with a XX1 or XO1 shifter and derailleur would offer a wider range of gearing that should be useful for most gravel races and mixed terrain riding. How many people are riding such bikes, or will build such bikes with the XD version of these wheels, is unclear, but we don’t see many of them yet.
We do think this driver option is a hint at where SRAM is heading with its single chainring drivetrains, and would not be surprised the least to soon see a wide-range road/cyclocross drivetrain from SRAM that embraces XD-based cassettes.