By Eric McKeegan,
In case you’ve been living in the stone age lately, SRAM’s XX1 is a new 11-speed drivetrain. What makes it interesting is that it is just that, an 11-speed group. Not 3×11 or 2×11, but a 1×11 group. A new wide-range 10×42(!) cassette is matched up with unique chainrings in sizes ranging from 28-38 teeth. You even get a choice of an 11-speed-only trigger or Grip Shift.
The first priority of this new drivetrain is chain retention. The fancy front X-SYNC rings have alternating tooth profiles, skinny for inner links, wider for outer links. Matching the tooth profile to the chain profile means less slop and more retention, both good things for a drivetrain.
The cassette’s 10 tooth cog necessitates a new cassette body standard, but let’s be honest here, if you have the money for this drivetrain, buying a cassette body (or a new rear wheel) isn’t going to deter you much. Several brands including SRAM, DT Swiss, and Mavic have or will have wheels and hubs ready to go as I type and we’re expecting to see a lot more at the show.
The rear derailleur, which sports the name X-HORIZON, is of the Type 2 variety, meaning a one-way clutch helps keep the chain from bouncing around, fulfilling the secondary priority of a quiet drivetrain. Instead of the standard slant parallelogram design, XX1 uses a horizontal parallelogram and an offset upper pulley. The difference between the two is more than I can (or care to) cover here so let’s skip ahead to the ride section. (You can geek out on how it works in this video from SRAM. – Ed.)
I got set up on a fully SRAM’ed out Trek Slash, and sped off to the trails with requests from the SRAM folks to shift under power, hit the chunder, and generally do my best to make this thing skip or drop the chain.
My first impression? I forgot about the whole wiz-bang newness spinning away down there. The gears shifted like a high-end drivetrain should and the chain stayed on even after stacking up pretty hard in some deep sand. The gearing range with an 32-tooth ring seemed just about right for the terrain here in Bootleg Canyon, Nevada, maybe even a little on the low side.
Who’s going to dig this new drivetrain? That still remains to be seen. It is marketed to be an option to anyone except full downhill riders, but will it have enough gearing range for XC racers? Will it keep chains well enough for Enduro guys to give up their chain guides? I can’t even hazard a guess as of yet, but I’m not going to complain about a company like SRAM taking a bold step like this to address drivetrain shortcomings we’ve all experienced.