I’ve been up and down and over and out, and I know one thing, the new SRAM XX1 drivetrain is the real deal. Forget about 27.5″ wheels, electronic shifting, and GPS optimized magnetic suspension, the new 1×11 drivetrain is the new voodoo I’m lusting for.

This drivetrain is built for mountain bikers. The kind of riding those of us who don’t care about labels like all-mountain, gravity, or trail oriented, love to do. It’s an amazing simply concept that improves and innovates upon existing 1x drivetrains.

What is this wonderful miracle and why am I transfixed? Check out our previous coverage for the technical debriefing or just hop past the break for first ride impressions…

The Tech

The XX1 system is similar to a traditional 1x setup, in that there is only one ring, but all of the drivetrain components are optimized for a single chaining. The current 1x systems are a compromise between optimal gearing and no fuss simplicity. 2×10 and 3×10 (or 9!) systems are great for getting up long grinds but not everyone needs 20 or more different gearing options.

The majority of my by bicycles are either single speeds or 1x because it’s simple, the terrain allows it, and I never have to deal with crossing or dropping my chain. The drawback? When a climb get too steep or technical, sometimes I find myself walking cross-train.

The secret to this new high-end drivetrain is the gigantic 10-42 cassette. It’s about as large as a 160mm rotor.  The gears are stepped the same as a regular 10 speed, until you get to the 36. By adding a 10 and a 42, SRAM has essentially added an extra gear on both ends.

If you're having trouble visualizing how the system works, think of it as a modern spin on the classic freewheel. The cassette slides on and then is threaded into place using the cassette tools you (or your LBS) already own.

The goliath cassette is too wide to fit on a standard freehub body, so black magic was performed to make the gearing work, and resolve some issues with current cassette designs. Each cassette is a work of art, and takes 8 hours to machine. After the part is completed, the largest cog and lock ring are pressed on. The lock ring is not a separate piece and is actually housed inside the cassette. Since the cassette is one piece and the lock ring is internalized, it won’t be able to tumble on the hub body. This stabilizes the cassette loads and will largely reduce scoring on soft freehub bodies and puts less wear on the outside hub bearings.

Despite the new freehub standard, dubbed the XD driver, there  are several wheelsets currently available from DT and SRAM, and Mavic will be following shortly. The only thing required is a new driver body, and does not impact the bearing location, ratchet mechanism, or axle hub. Dish remains the same and no frame modifications are necessary. Interested manufacturers will be required to sign SRAM’s Licensing agreement to get on board.

Working in conjunction with the monstrous new cassette is the uniquely sculpted chain ring and modified carbon cranks. The cranks are the same carbon arms used elsewhere but have a modified smaller BCD. The spider is designed so that the rings can easily be removed by simply undoing the bolts and rotating.  No crank removal necessary. Rings will be available in 28-38 sizes, stepping up in two tooth increments. Ideally, racers would own two or three different front chain rings for different terrains, and simply swap them as necessary. Chain length might have to be corrected, but would probably be OK unless you’re changing from one extreme to the other.

The chain ring is special because the teeth are asymmetrical, instead of being designed to shift, and every other tooth is hooked in order to hold the chain in place (this is why the chain rings are only available in even sizes.) The chain will only mount in one direction and is finished by a exclusive pressure polishing system which greatly reduces friction. During testing, SRAM found that the new XX1 chain lasted almost 4X longer than a normal 10 speed chain. Expect this tech to trickle down soon.

SRAM claims that this new 11 speed chain is stronger than the eight speed chains which were commonplace only a few years ago. Most chain failures are initiated by front shifting, which usually causes an outer plate failure, or a pin to pop. Wider pins, like those found on 8 speed chains, put more leverage on the outside plates when shifting. The new XX1 chain is marginally narrower than a 10speed chain because of its thinner roller.

The last exceptional piece of kit is the X-Horizon rear derailleur. This is the first of its kind to be put into production by SRAM, because it is optimized for a single chain ring, while rear derailleurs are required to take up the slack and shift between 2-3 front chain rings. Instead of having to swing inwards and down to cover the entire range of gears, the XX1 only needs to swing downward to adjust for chain gap. This requires a different and larger offset pulley than the standard 7mm, and isn’t necessarily a brand new design. Six/Seven speed road bikes from the prehistoric era also utilized a similar “straight-parallelogram” design because the cassettes had such narrow gearing.

Ride Report

As an avid fan of 1x systems and  a “slow and steady” type of climber, the XX1 system was pure seduction. It just worked. The two hour test ride consisted of mainly technical rocky climbs, and some short fast undulating descents, including a small portion of the Crankworx Enduro course. Throughout the climbs the tremendous range of gears meant there was always another easier one waiting in reserve. As steep pitches appeared around a corner  it was easy to grab a handful of shifter and shift through several gears – even when hammering. The range of gears was simply stunning.

Despite running no chain guide, the XX1 clutch enabled derailleur and chain ring performed. Not a single rider suffered a dropped chain. While there where some steep and rough patches of terrain traversed, it would take a longer ride over familiar descents to determine how well the system really worked sans guide. The bike just looked so unfinished and alien without a front derailleur or guide.

Matchmaker compatible and available as either a trigger or grip shift

If you’re a hardcore cross country racer or masochist who gets their pleasure from tach’n it out uphill, then this new system probably isn’t the right option. Conversely, if you’re someone who just loves to go mountain biking and likes the simplicity of 1x gearing – this probably won’t make you faster, but you’ll be much happier. Happiness retails for $1499 USD and should be available this October.

The components are priced squarely between the XX and XO ranges. Each component weighs slightly more than its XX counterpart, but due to the lack of FD, multiple chain rings, and front shifter, the overall weight is less. You can expect this new technology to eventually trickle its way down into more affordable iterations, just as the 2×10 system are now available even at the entry level x-5 price point.

Claimed Weights:

  • Cassette, 260 gm
  • Crank (w/ BB), 650gm
  • Rear Derailler, 220 gm




  1. Quinn on

    I am as you are, very excited about this drive train, however 1 question keeps popping up, Every time I have run a 1x drivetrain, it has needed chain guides of one kind or another, so I am wondering how this drivetrain deals with that, is there something with the new trick rear derailleur?

  2. ccolagio on

    Quinn – read the article(s) closer – the rear der and alternating chainring teeth profile limit the need for a chain guide

  3. Peter on

    Quinn, you obviously didn’t read the entire article. SRAM has redesigned the chain and chainrings to so a guide is not necessary, at least in all but the most extreme conditions. The chainrings have hooked teeth to hold the chain on the ring.

  4. Dan E on

    Very few xc racers at sport level and above use more than a 1×10 gear range even though they might have 2×10 at their disposal…its faster to jog wherever that granny is needed…and any shorter steeps are conquered by the momentum gained before the pitch, not while on it…on a 29er 2×10 running a 28-front/36 tooth rear, you get the same hill-climbing ratio on a 1×11 with a 32 front/42 rear.

    See Sheldon Brown’s website to calc it out…simplify the ride.

  5. Taylor on

    “If you’re a hardcore cross country racer or masochist who gets their pleasure from tach’n it out uphill, then this new system probably isn’t the right option.”

    Yep, definitely not the right option for racers seeing as the olympics were just won on this drivetrain. This is an amazing option for anyone who loves 1x systems, especially cross country racers.

  6. Ricky Bob on

    Climbing efficiency is effected by more than just gear ratio. I’m sure I’m not alone in wondering how the chainline affects the climbing ability of this bike. Normally suspensions are designed to be optimized for climbing in the small ring, but this setup has no small ring. Are we compromising climbing efficiency for the sake of simplicity and a marginal weight savings?

  7. Ck on

    Love the system, the idea and the tech behind it.

    But I really don’t need a cassette machined out of a block of aluminum for eight hours. I hope they find cheaper, faster manufacturing methods for this stuff so that it doesn’t sit at the XX level for the next three years without trickling down.

  8. Gillis on

    I just went to a 1×10 a month ago, and its been great. My chain guide didn’t arrive until about a week after I install the set-up, including a XTR rear der. I rode it around like that and I gotta say I felt like I could have gone without a guide. With the XTR’s tension lever (don’t remember the technical name) the chain never came off. I still put the guide on to keep my mind at ease.

    As far as gearing is concerned I don’t think an extra cog or gear option would do much (for me). And definitely not as a proprietary system.

  9. mike on

    I wonder if a 3d printer would save cost on those cassettes vs. 8 hours of chiseling each one out of a block of alu . Looks like a beauty. I’d definitely rock the cx version of this group when they get around to it.

  10. Paul on

    Sooo…. I think there’s a cheaper version.
    Using a Canfield 9-36T 10 spd stack, and run a 28T spiderless ring…say on a Middleburn crankset. No special 10 spd shifter, chain, or rear mech. $300 for the rear hub and first few cogs of the stack, a 11-36T stack, and if you need a 28T front ring…and a solid 1×10 setup.

  11. Hawkfan on

    I sent an e-mail to Chris King and this was their response to the conversion to SRAM XX1:
    “At this point the ISO hub is not compatible with Sram’s XX1. We are pretty buried with new projects right now, so we’ll keep our eyes on it and see if the platform spreads enough to warrant a major overhaul of our products.”

    I hope I received bad information, but they told me no for XX1. Anyone hear different???

  12. Jake on

    As an avid proponent of 1×10, I am very excited for XX1. This article did a good job of confirming my hopes that the system be reliable, but the author doesn’t seem to respect the speed and power. If Nino Schurter can take silver on a very taxing olympic race course (granted, he could win on almost anything) with it, then I think this is the perfect system for “hardcore XC racers.” It certainly can make you faster by making you stronger.


    I’m a firm believer in 1x systems. I had a 1×9 on Rip9 and now 1×10 on a Superfly 100. 1×11 and $1,500 is ridiculous. The ability to run without a chainring guide is very cool, but a new hub standard is not. There are enough “standards” out there already. The overwhelming majority of riders don’t need such a wide range. If lower gears are needed, then SRAM and Shimano should make cassettes like 13-38 or 14-40 in a 10spd. When was the last time you needed an 11 cog on the dirt? The R&D should be for an internal gearbox in the BB area. I might pay $1,500 for that.

  14. Saris on

    @ El Grande

    I would not classify the London Olympic XC course as containing any particularly large elevation changes. According to the course description “The course is 4.7km long with 172m [ aprx. 564 ft] of elevation change each lap.”

    The XX1 was used to great success by SRAM sponsored athletes in the 2012 London Olympics, but it probably won’t be the first choice for grueling races like the Leadville 100.

  15. Justin on

    Yes, the olympic cross country course was not even a mountain bike course in the sense that there were zero mountains and only rolling hills with lots of switchbacks and moderate grades over smooth singletrack.

  16. Andrew on

    I don’t think the course was flat…..

    Olympic XC 172/4.7 = 37 m climbing per km

    Leadville 4300 /160 = 27 m climbing per km

  17. MBR on

    Sure to be the next big trend. Not enough range for mortals that live in the Rockies. I wonder how much a replacement chainring and cassette will cost? Oops…There goes the retirement and/or kid’s college fund…

  18. MBR on

    Part-II More mortal ranting
    For all the comments that try to draw a parallel with what the Olympians ride and what us mortal types ride, are you serious?

  19. Slc29er on

    I run a 1×10 with a bash guard and no front guide. Haven’t ever dropped my chain on a rigid 29er or cross bike. I am sure that would not be the same on a suspension bike.

    What I want to see this for is my cx bike. 1×11 would be sweet with a 38 or 40 front ring. I’m already running a disc brake cx bike. Hope SRAM will make an 11 speed road brifter!!!

  20. Jeremy Ling on

    So, this article is dated 17 Aug 2012 and it is now the end of Dec 2012…..
    Any followup review on how the XX1 is holding up after 3 months of riding? Particularly on chain retention after that chainring wears some of its metal?

  21. Disker on

    Get RID of the 10 tooth cog on the back and make this cassette so that you CAN use it with a normal hub !!!

    I live in the mountains and DO NOT need a 10 tooth cog !!! Also, the MAJORITY of people are NOT racers so it doesn’t make sense to force ppl to make changes to their hubs for a 10 tooth cog.

    SRAM I hope that you are listening !!! 😉


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