After months of rumors, leaked photos, and plenty of heated internet speculation, it's official: SRAM's new XX1 and X01 1x drivetrains go to 12. Twelve speeds that is - both groups are based around a massive looking, 10-50 tooth cassette. Called 'Eagle', the project initially began with the goal of improving SRAM's current 1x11 offerings, but as the company's engineers dove deeper into their tasks, they realized it was possible to add a 50 tooth cog with only a minor weight penalty, a move that would increase the drivetrain's gear range to 500%. That number is greater than the range of a typical 2x10 drivetrain, effectively squashing the complaints of anyone who'd been hesitant to commit to a single ring drivetrain due to the available gear range. In fact, SRAM is so certain that 1x drivetrains are the way forward that they've disbanded their mountain front derailleur division. Front derailleurs have already become a rarity on most high-end mountain bikes, and they'll be even more of an oddity when the 2017 models debut.
It's easy to puff your chest and scoff at a 50-tooth cog as being only for out-of-shape riders, and there's no denying that the dinner plate-sized ring does look odd at first, but Eagle is about more than being able to ride up vertical walls. It's about having a wider gear range, and SRAM encourages riders to choose the chainring size that best suits their needs. For instance, if you're perfectly happy with the climbing gear on a 1x11 setup with a 32-tooth ring and a 10-42 cassette, going with a 36 tooth ring on an 10-50 cassette will feel nearly the same when climbing, but greatly extend the higher end of the cassette, making it much less likely that you'll spin out on a high-speed descent.
There will be two different Eagle drivetrains - XX1 and X01 - when the groups hit stores this June. XX1 is positioned as SRAM's flagship cross-country group, while X01 is aimed at more aggressive riders, those who prefer more technical terrain, and may even find themselves rolling up to the start of an enduro race.
PC-1290 Eagle Chain
Most of us don't spend much time thinking about a bike's chain unless it's making noise, skipping, or coiled in a snake-like heap by the side of the trail, but the new PC-1290 chain is worthy of a closer look. It's an impressive feat of engineering, one that required a new manufacturing process and the German-made tooling to go with it.
The inside of each plate has had any square edges removed, a measure that's said to create a quieter and longer lasting chain. In fact, SRAM say that the new chain is the “quietest, strongest, and most wear resistant chain in the world.” Those are bold claims, and we'll be putting them to the test once we have an Eagle group in for review.
The chain itself is slightly narrower than an 11-speed chain, and the pins on each link are now completely flush with each side, a space saving measure that allowed SRAM to squeeze in that extra cog without needing to resort to a different driver body. Cassette
The tooth count of the first 11 cogs on the Eagle cassette are the same as they are on SRAM's 11-speed 10-42 cassettes (10-12-14-16-18-21-24-28-32-36-42), with the 10-tooth cog sitting in exactly the same position. The spacing between each cogs is ever-so-slightly tighter, and the final 50-tooth cog sits a little closer (2mm to be exact) to the spokes than the 42-tooth cog would on an 11-speed cassette. Despite the extra cog, the cassette still works with a standard XD driver body.
The 10-50 tooth cassette weighs a claimed 355 grams (87 grams more than 11-speed XX1), and is constructed using SRAM's X-Dome technique, where nine of the cogs are machined out of a single piece of steel billet. Two of the three remaining cogs are also made of steel, and the final 50-tooth cog is aluminum. For the numbers oriented out there, a 10-50 tooth cassette offers a 500% gear range, versus 420% with a 10-42 tooth cassette. Both groups share the same cassette construction, although XX1 comes in a snazzy gold-colored option that adds to the bling factor, and $60 to the final price. Derailleur
To accommodate the wider range cassette, the Eagle's 12-speed specific rear derailleur has a 14-tooth lower pulley wheel, two teeth larger than its 11-speed sibling. Other updates include version 3.0 of SRAM's roller bearing clutch mechanism, a revision that's designed to create a smoother feeling as the cage moves forward, although it's still not externally adjustable due to a patent held by Shimano. The Cage Lock button has also been relocated away from the front of the derailleur to better protect it from impacts.
Even the B-knuckle (the portion of the derailleur that's threaded onto the hanger) has been tweaked to help keep the mounting bolt from unthreading itself. There's now a bushing around the mounting bolt, allowing the derailleur to pivot forwards and back without bringing that bolt with it. The XX1 Eagle derailleur gets a carbon fiber cage and a titanium spring, features that allow it to weigh in at 12 grams lighter than X01. 12 grams isn't much, but remember that XX1 is aimed at elite-level XC riders, where gram-counting is a way of life.
The teeth on the Eagle chainring look dramatically different from SRAM's previous narrow-wide offerings, with a deeper, more hooked profile that's supposed to increase chain retention, along with reducing the amount of noise, even when the chainring is worn.
Notice how material has been machined away at the top of each tooth? That's the spot where a little nubbin of metal used to develop as the chainring wore, which could create a grinding sensation, especially when the chain was shifted to the far ends of the cassette. On the topic of chainring wear, SRAM says that the new design should last more than four times longer than their previous narrow-wide rings – that means most riders should be able to get multiple seasons out of one ring.
It's also worth mentioning that the X-Sync 2 chainrings are backward compatible with 11-speed drivetrains. Available in 30, 32, 34, 36, and 38-tooth options, they're direct-mount only, and will retail for $99 USD. XX1 and X01 Eagle Cranks
The carbon XX1 and X01 cranksets are both suitable for XC and trail usage, but the X01 cranks have been constructed to survive the rigors of all-mountain and enduro riding as well. The XX1 cranks are completely hollow, while the X01 cranks have a foam core, and are tested to SRAM's gravity standard. 5 Quick QuestionsWho is Eagle for?
Riders who want a purpose-built, single ring 12-speed drivetrain with a 500% gear range. Do I need a bike with 12x148 rear spacing to run Eagle?
Nope, and it works with a regular XD driver body. The ability to run an Eagle drivetrain isn't dependent on your rear axle width. That being said, Boost spacing can help frame designers create enough chainring clearance to fit the larger chainrings that many riders will be using with Eagle.Why not go to 13 speeds? Or 15? Why the one cog jump every few years?
According to Chris Hilton, SRAM's drivetrain product manager, “Sometimes people, including ourselves [SRAM], need time to acclimatize to change. When we looked at XX1 originally there was a fair bit of internal stress about the aesthetic change that XX1 had.... People getting used to these things slowly has made it easier for us. Can you go bigger? Yeah, you can go bigger, you can go more. Any of these things are possible, but we try to understand how much are people going to take, and I think that if you look at things like hub standards right now people have pretty clearly told me they don't want any more... People have had enough.” When will a more affordable version hit the market?
It took four years for SRAM's more budget-oriented 1x11 drivetrains to hit the market, but the trickle down for Eagle could be quicker, although SRAM couldn't reveal an exact timeline. What do I need to make the switch to a 12-speed drivetrain?
At the minimum, if you already have an XD-driver equipped hub and SRAM direct mount compatible cranks, upgrading to Eagle requires the purchase of a cassette, derailleur, shifter, chain, and chainring.
I was able to spend a day on each group riding the trails of Massa Marittima, Italy, in order to start getting a feel for Eagle's real world performance. Of course, how a drivetrain fares after months of use and abuse is the true test of its worth – keep an eye out for a long term review later in the year, once we've put in some serious miles.
Day one was spent aboard a Scott Spark, one that had been stripped of its usual mess of cables and remotes and turned into a lean and mean, SRAM and RockShox equipped cross-country machine. That day's loop wasn't particularly technical, but it was full of short climbs and tight, twisting descents, the type of terrain that regularly requires multiple quick shifts. Shifting performance was exactly on par with what I've come to expect from SRAM's top-tier offerings – there's a crisp and precise jump from cog to cog, with a distinct 'thwunk' as the chain settles into place. The most immediate sensation was just how smooth the drivetrain felt. Sure, a brand new drivetrain will always feel better than one that's had the snot beat out of it for months, but this was something different. The interaction between the chain and chainring feels absolutely seamless, almost as if it were somehow one unit rather than two separate components. How much of this is due to the chain and how much is related to the chainring is hard to tell, but it will be interesting to see how an Eagle chainring feels with an 11-speed chain (the chainrings are the only part of the system that are 11-speed compatible). In any case, the drivetrain felt remarkably smooth, no matter what gear the chain was in.
What about the jump up to the 50-tooth cog? That didn't pose any problems, and even though it's the largest jump on the cassette, the chain hopped right up without any hesitation. The 8-tooth spread does mean that the 50-tooth cog feels like more of a bailout gear, one that you would shift into as a last resort, whether that's to grind out the last miles of a soul-crushing climb, or when suddenly faced with a near-vertical section of trail.
After spending the last few years aboard 11-speed drivetrains it did take a little time to get used to having a wider spread of gears, and an extra click at the shifter. I found myself glancing down a couple times to see just how many gears I had left on the cassette, and in each instance there were more remaining than expected. That's a good thing, especially when compared to the alternative, where you fruitlessly stab at the shift lever hoping for just one more gear. I've honestly never had any issues with the gear range of a 1x11 drivetrain with a 10-42 cassette, but there have been plenty of rides where I would have shifted into an easier gear if it were available, which is what the 10-50t cassette accomplishes. I usually run a 32-tooth chainring on 11-speed setups – that's what works best to tackle the long, steep logging road climbs around my home – but with Eagle I'd likely bump up to a 34-tooth ring, thus gaining a slightly easier climbing gear, as well as a harder gear for high-speed descents.
The second day of riding was a little rowdier, located on the trails that were going to be used for the first round of the Superenduro race series. My ride was the Lapierre Spicy, a bike that epitomizes the saying, “don't judge a book by its cover.” Despite its ugly duckling looks, it's a good representation of the style of bike many riders are gravitating towards, with 160mm of travel and longer, slacker geometry, the type of bike SRAM expect the X01 group to end up on. Like the XX1 group, X01 felt extremely smooth, with accurate shifts and no dropped chains, even on the rougher, rockier trails. Other than price, and a minor weight difference, there's no functional difference between the two groups, and in a blind test it would be virtually impossible to tell one group from the other.
|The battle for drivetrain dominance continues to rage on, but this is a fight that benefits the consumer, and mountain bikers now have more options than ever. One thing is abundantly clear - the front derailleur's extinction has never been more imminent. The launch of relatively inexpensive 11-speed drivetrains from SRAM and Shimano, along with the plethora of conversion kits and aftermarket cassettes from smaller players means that there are 1x choices to fit just about every budget.|
Eagle's ultra-wide range and the host of refinements that went into producing the 12-speed group will undoubtedly make it a popular choice on 2017's top tier bikes - it will be interesting to see how Shimano chooses to respond. - Mike Kazimer
Visit the high-res gallery for additional images and spec sheets.
Photos: Adrian Marcoux / Mike Kazimer