Feb 15 Update 2: Graphic comparison with double- and triple-ring setups added.
Recently, while descending a rough, loose descent, my attention was drawn to the rattle of a pair of hydraulic lines. Annoyed at first by the intrusion, I soon realized the reason that the hoses’ noise had come to the forefront was the fact that nothing else was making noise. No chainstay slap. No rattle in the front derailleur. No whir of a chain guide. Nothing but the soft thrum of the tires- and the faint rattle of hydraulic hose.
Even before laying hands on hardware, the more I thought about SRAM’s new XX1 group, the more it made sense. Sourcing a new freehub can be a hassle and the exquisite cassette is extortionately priced- but the logic is sound: What if you could remove the gearing redundancy inherent in even 2×10 setups? What if you could de-clutter crowded handlebars? What if you never dropped another chain? What if you could drop between 0.5 and 1.5lb from your bike? What if you gave up virtually nothing in return? All are big questions and exciting possibilities- and are the promise of the 11 speed drivetrain.
But I never thought to ask if it would be so wonderfully, eerily quiet.
So SRAM aren’t suggesting that a 1×11 setup will replace everyone’s 2×10 or 3×10 drivetrains. But those who are running a trail-style double should take note: an XX1 group with a 30t chainring covers the slightly more ground than a 24-32t chainring/11-34t cassette combination. It just does so in slightly fewer steps, with considerably less overlap. Take a look at the graph above. The blue lines represent the gear ratios provided by a 24-34 2×10 setup. (Want gear inches? Multiply the ratio by your chosen wheel size’s diameter.) The red line represents the ratio provided by an XX1 group with a 30t chainring. The XX1 group covers the same ratios- matching the 2×10 setup’s high and low gears almost exactly- just in fewer steps.
So, if you’re a rider who rarely shifts into the big ring of that triple, then XX1 may be for you. Even if not, there’s a good chance that XX1 will cover most of your existing gearing: the high gear on an XX1 32 is equivalent to a 42×13 while the low is close to a 24×32; the high gear on an XX1 34 is equivalent to a 42×12 and that ‘ring’s low works out about the same as a still-manageable a 24×30. To make a long story short: the 10-42 XX1 cassette packs a surprising range.
While Tyler and Saris have gone into the technical details in depth, there are a few key things to call out. At the front, a version of SRAM’s proven X0 carbon fiber crankset uses a dedicated spider that accepts 28-38t XX1 chainrings. The ‘rings themselves have tall teeth of alternating thickness, to better fill the alternating narrow and wide gaps in the chain and reduce the liklihood of the chain derailing. The chainrings can be swapped without requiring the cranks’ removal and are handsome save an odd smooth:sharp transition between the spider and ‘ring and anodized teeth that look tatty awfully quickly.
The 11s XX1 chain is ever-so-slightly narrower than a 10s model (which will rub on the cassette- don’t be lazy) with gram-shaving outside link cutouts. That chain is given direction by the substantial XX1 rear derailleur. The tightly-sprung mech uses Sram’s Type 2 clutch, which uses a 1-way bearing to forward (slack-creating) cage movement while allowing for easy rearward (slack-reducing) movement. The derailleur geometry is optimized for the massive 10-42t cassette and single front ‘ring. It’s a big chunk of aluminum and composites- and it works well.
Moving rearward, it’s hard to understate the size of the XX1 cassette. The 42t cog is bigger than a 160mm disc rotor and somehow manages to make American Classic’s trademark high hub flanges look… small. All but the aluminum top cog are machined from a single chunk of steel. That and the captive lockring contribute to the staggering $425 retail price. To make room for the 10t cog, an XD driver (freehub body) is required- but should be easy to find before long. Our most recent list of supporting manufacturers is here.
Conducting the whole orchestra is either an XX1 trigger or GripShift shifter. As would be expected, the shifters can be mounted via their own handlebar clamp or combined with Avid brake levers and/or RockShox remotes for a clean cockpit. Less expected, they also play very nicely with arch rival Shimano’s latest brake levers. Once a compatible wheelset is located (or an XD driver is installed on your existing wheels), XX1 setup is easy: the crankset and cassette install using standard tools. A nice coated shift cable is included, as is a stretch of housing. The chain is designed to be run without slack with any suspension fully compressed: setting your largest anticipated ‘ring up this way will allow changes of up to two sizes without any chain length tweaks. SRAM’s excellent Powerlink makes for fuss-free installation (and chain cleaning, if you’re so inclined).
On the trail, XX1 really is all it’s cracked up to be. Chain slap is nonexistent and I have yet to drop a chain. Clicks at the shifter are distinct but the action lighter than even some recent Shimano groups, proving that the pendulum has begun to swing in the opposite direction. With about a month’s use, shifting is smooth- even by today’s high standards. Compared to the XTR triple group (with lightweight carbon cranks) it replaced, XX1 has shaved almost a pound from the bike shown here- the group has the potential to take trail bikes that much closer to XC bikes with a fraction of the travel- and XC bikes into freakishly light territory.
The clear-eyed among us will balk at the (consumable!) cassette’s $425 price tag or for paying $175 for a single shifter. And they’re right to. They will complain about the chainring’s dedicated bolt pattern- even if the carbon fiber crankset itself is the deal of the group at $325. Real tears will likely be shed when the $305 rear derailleur ingests its first (and last) stray branch. But those concerns quickly fade in the face of the group’s smooth, secure, and near-silent performance.
It’s early yet, but I already believe that in XX1 we’re seeing the future of mountain biking. SRAM have managed in one fell swoop to substantially simplify the drivetrain, improve its performance, and knock off a big chunk of weight- all with minimal compromise. It will take some big days in bigger mountains to say for sure, but it sure looks from here like the 1×11 drivetrain is the way forward. SRAM are not shy about asking for top dollar for their latest and greatest- but if history is any indication, the technology will quickly trickle down to more attainable price points. I can’t wait for the day that it does- and I can recommend the group without reservation. More as the miles rack up…
Plan on setting aside about $1,300 (plus $60-100 for an XD driver) if you’d like your own XX1 group.