SRAM XO Drivetrain and Brakes Review

SRAM's XO group is firmly entrenched as the company's high-end, do everything component set and is designed to meet the needs of demanding riders from all over the world. We previewed the 2011 XO group last year and now, after subjecting it to one of the wettest, most unpleasant Wet Coast winters in recent memory, we have some pretty decent ideas about the performance and durability of the lineup.




Installation and setup: Installing SRAM's XO group onto the test rig was a straightforward process, and there were only a couple of minor issues to deal with before the bike rolled out the door. The high-mount, two speed XO front derailleur relies on a band clamp to keep it connected to the frame and to make for easy alignment between the chain and cage. Much like the front derailleur, the medium cage, ten-speed XO rear derailleur bolted onto the bike and was ready for fine-tuning following the installation of the shifters.

The Truvativ GXP bottom bracket threaded smoothly into the test frame and the bb accepted the 2x10 Truvativ XO crankset without any binding or fiddling around. After being torqued to specification, there was no play or unwanted movement in the system and it remained problem free for the duration of the test. The ten-speed SRAM XG 1080 cassette (11t-36t) slid snugly onto the freehub and was held firmly in place by a lock ring.




SRAM's excellent MatchMaker X clamps kept the handlebars clean and well organized, with the shifters and brake levers sharing a single MatchMaker X clamp on each side of the handlebar. The beauty of this system is that it meshes well with other products in the SRAM lineup, and the XO shifters and brakes worked well with the XLoc clamp for the XX Revelation that was run for the duration of the review. The XO shifters have a good measure of adjustment that allows riders to set each of the shifter units into one of two inboard / outboard positions, move them towards the front or rear of the bike, and to set the angle of the large thumb paddle. Avid's XO brake levers, calipers, rotors, and adapters didn't require any fiddling or special spacing after being loosely bolted on to the frame and fork for fine-tuning later on.

Once the key components were installed and cable housing was cut to length, the derailleurs were connected to the shifters using the included teflon-coated cables, and a SRAM 1091R chain was installed after the correct length was determined using SRAM's installation guidelines. To finalize the chain install, you need to hop onto the bike and put some of your weight onto the pedals so that the PowerLock connecting link can snap into place. Following the installation of the chain, each of the derailleurs' limit screws was set and any necessary fine-tuning was achieved by using the barrel adjusters on the shifters. Avid’s CPS alignment washers helped center the brake calipers on the rotors after clamping down on each of the levers and then tightening the calipers onto their mounts.

While the installation of the XO group was largely a pain-free process, there were a few points that new owners of the group should take note of. First, many of the small bolts for the cockpit controls require a T-25 Torx wrench which may or may not be a problem for home mechanics, depending on the completeness of their toolboxes and / or multi-tools. Second, and more significantly, both brakes were mushy out of the box and required bleeding which, while being a straightforward process, requires an Avid-specific bleed kit. Also, note that it's often necessary to cut your brake lines to fit your bike - if this is something you need to do, you'll need to bleed the brakes regardless.


SRAM XO technical info: For 2011, SRAM has implemented major changes to the XO group and nowhere are these revisions more noticeable than in the drivetrain. Up front, the 2x10 Truvativ XO crankset (175mm, 39T/26T, 658g) uses molded carbon fiber arms with a foam core instead of an aluminum skeleton, which is meant to save weight without sacrificing much in terms of stiffness. If the 39T/26T ring combination isn’t your cup of tea, the 2x10 crankset is also available with 28T/42T. If you're looking for a more traditional three ring setup or dual rings with an outer bash guard, you'll need to look at the 3x10 version of the crankset, which uses a different BCD than its dual ring cousin. The bottom bracket is Truvativ’s GXP model (106g, no spacers) and the test unit arrived with some super smooth bike-specific ceramic bearings and a total of eight seals that are meant to protect the internals from the elements. The bottom bracket is also available in PF30, BB30, and GXP PF configurations. Truvativ’s X-Glide alloy chainrings (39T/26T) are nicely machined and use specially positioned rivets that are designed to match the rings’ teeth with a specific part of the chain for better shifting performance. The SRAM PowerChain 1091R (257g) has chrome hardened hollow pins and is held together by SRAM’s tool free PowerLink connector. At the rear of the bike, the ten-speed 11t-36t SRAM XG 1080 cassette (242g) is a veritable work of art that is light thanks to the absence of a spider, slides smoothly and snugly onto the freehub body, and features much of the same technology as is used on the top tier 1090 cassette.




Shifting duties are taken care of by the newest iterations of SRAM’s highly successful trigger shifters and derailleurs. The 2x10 XO shifters (232g) used in this test rely on SRAM’s 1:1 Exact Actuation technology for shift performance to move the derailleur the same distance that the shifter cable travels during shifts – 1mm of cable travel moves the derailleur 1mm – which, SRAM claims, results in a reliable, easy to setup shifting system. The front shifter is available in 2x10 and 3x10 specific versions; the 2 speed front shifter used for this test was connected to SRAM’s XO high clamp front derailleur (136g), although it’s available in low clamp and direct mount models too. The medium cage XO rear derailleur (206g) is designed for use with the 2x10 system and is compatible with the SRAM 11t-36t cassette. The rear derailleur is also available in both short and long cage formats for downhill and 3x10 applications, respectively.

• XO rear derailleur MSRP $234 USD
• XO front derailleur MSRP $82 USD
• XO 10spd 2x10 shifter set MSRP $238 USD
• XO 1080 cassette MSRP $328 USD
• 1091R chain MSRP $76 USD
• XO crankset (2-ring, GXP) MSRP $395 USD
• GXP bottom bracket MSRP $36 USD


SRAM XO performance: Once everything was clamped onto the bike and adjusted for riding, the test rig was rolled out into the forests of southwest BC for an old-fashioned, winter beat down. Throughout the review period, the Truvativ XO crankset offered excellent performance in every condition, be it rain, sleet, snow, or sunshine. The crank arms are plenty stiff and the system provides good power transfer while coming in at a reasonable system weight. Truvativ’s GXP bottom bracket ran exceptionally smooth on its ceramic bearings and the unit has noticeably less drag than its non-ceramic counterpart. After a full winter’s riding on the trails, the crank arms are showing a little bit of wear from shoe rub and a few minor chips in the carbon’s clear coat, but nothing that’s out of line and nothing that is cause for concern. The bottom bracket was repacked a few times over the winter and is still running well: the drive side bearings remained smooth for the duration of the test; the non-drive side is running a little ragged, but is still more than acceptable. The 39T chainring took a bit of beating when it came into contact with logs and rocks, and the strikes resulted in a couple of bent teeth on one section of the ring. A bashguard would eliminate these encounters, but the profiling on the outside of the 2x10 spider prevents it from being an option.




SRAM’s XO shifters and derailleurs are consistent favourites amongst both hardcore riders and weekend enthusiasts and that popularity didn’t come about without reason. Front shifting was excellent throughout the test and the two speed front derailleur moved the chain back and forth between the 39T ring and its 26T counterpart with startling efficiency and immediacy. I’d have to let off the gas to move from the smaller ring to the larger once in a while, but shifting under load was pretty good and was easily comparable to any of the high-end offerings from other manufacturers. Overall, the gearing range on the front rings wasn’t necessarily too tall, as I had no problem making all of my regular climbs using a combination of both rings, but I did find that I was shifting out of the 39T ring and into the 26T ring earlier than I would if I were running a 36T/24T setup. This is meaningful because many full suspension frames don’t pedal as well in the smaller ring as they do in the larger one, whether they suffer from pedal feedback, pedal bob, or a similar issue. In addition to encouraging you to stay in the larger ring for longer and reaping the benefits of improved pedaling performance on your fully, a bashguard/36T/24T combo would also alleviate the chainring damage mentioned above.




Rear shifting was impressive too, and the indexed clicks between upshifts and downshifts were precise and well defined without requiring any major effort. Shifting into lower gears was smooth and nearly flawless, although, under load, the chain didn’t move into the 36t rear cog as smoothly as it did for the rest of the gearing range.

Shifter and derailleur durability was great, and everything held up admirably despite a number of crashes and some contact with immovable objects. The cassette looks very good with little appreciable wear, even on the most heavily used cogs. I was also pleased to see that SRAM has moved away from using plastic inserts with the mech's limit screws, as the little plastic sleeves were notorious for stripping under normal maintenance and it was difficult, some may say impossible, to find replacement pieces, which was pretty frustrating on a such a pricey derailleur.

The SRAM 1091R chain that was included with the XO group failed about a month after installation, breaking into numerous pieces under regular use. It’s difficult to know whether the failure was caused by improper installation, a manufacturing defect, or just bad luck, but it was replaced with a SRAM 1031 chain (267g), which has performed admirably and without fail. Also note that SRAM’s PowerLock connector isn’t as easy to remove as its 9-speed cousin so don’t rely on it to get your chain on and off the bike, especially for trailside repairs.


Avid XO brakes technical info: Avid's XO brakes sit near the top of the company's hydraulic disc brake lineup and are jam packed with nifty proprietary features that set the system apart from the competition while offering very good performance on the trail. The brake systems rely on Dot 5.1 hydraulic fluid, which doesn't boil as quickly as Dot 4 fluid and is meant to provide better fade resistance during long runs.




On the handlebars, Avid's Power Reserve Geometry is a fancy way of describing the pivot location for the carbon fiber brake lever, which is positioned close to the bar and results in a natural feeling inward movement and allows the rider to squeeze power out of the brakes when it's really needed. The levers feature an integrated reservoir and master cylinder that utilize Avid's Taperbore technology, which is designed to allow more fluid to pass through the brake, providing better control, heat management, and power than earlier versions of the company's brake systems. Adjustability has always been a hallmark of Avid's brake systems, and the XO brake levers continue to offer a good range of customizable features to ensure a good fit and feel for most riders. The XO levers forgo the Tool Free Reach Adjust that was found on the Elixir CRs in favour of the tried-and-true method of using a tiny allen wrench, but they retain the Contact Point Adjustment feature that has graced top-shelf Avid brakes for years.




At the wheels, the two-piece calipers feature top-loading aluminum-backed organic pads, an adjustable banjo, and Avid's well-known Tri-Align Caliper Positioning System (CPS). Avid's G3 CleanSweep rotors have eliminated the annoying 'squabble' that plagued older brake models from the manufacturer. The brakes - levers, lines, calipers, 185mm rotors, rotor bolts, no MatchMaker clamps, no adapters - weighed in at 322 grams and 345 grams for the front and rear, respectively, which is extremely competitive, but not industry leading.

• Avid XO brake MSRP $245 USD (160mm rotor, per end)


Avid XO brakes performance: Under pressure, the XO brakes performed extremely well. Compared to a number of competing two-piston braking systems on the market, I found Avid's XO brakes to be a little 'grabby' off the top, but stopping wasn't as sudden as is common in most four-piston setups. Once I'd adjusted to the brakes' modulation range, however, I had no problem keeping the brakes from locking up during descents and was able to control their power output without any problem. If and when I wanted to stop without reservation, the XO's provided ample power to slow me down with the 185mm rotors that were included with the set, and you can run them with larger or smaller rotors depending on your needs and intended use. I didn't have any issues with brake fade during the test.

I got about four months of regular trail riding out of the stock organic brake pads, which is slightly above average for me, and replacement was a piece of cake, thanks to the top-loading slots on the caliper. One of the retainer clips that hold the pads against the caliper pistons ended up mangled after being caught between the pad and the rotor, and it was a bit of a chore to find a replacement, so make sure you save your old, undamaged ones when replacing the pads.

As mentioned above, the brakes were soft out of the box and they required bleeding before being ridden on serious trails. I'm very familiar with the bleed process, but it still took me a few kicks at the can to get an acceptable feel at the lever. Also note that the bleed process requires an Avid-specific bleed kit which is not included with the brakes; it's a worthwhile purchase if you're into maintaining the stoppers on your own, but it does add a bit to the cost of the set. The bleed kit can be used on other SRAM products that rely on suspension fluid, including the XLoc remotes that are featured on the Reverb seatpost and RockShox's XX forks.



Product improvements:

• Better out of the box brake performance. Note: For 2012, SRAM has redesigned its TaperBore system and focused on providing better factory bleeds on its brakes, which should alleviate some of the brake bleeding issues that were encountered during the review process.[/li]

• More gearing options for the 2x10 crankset. Many riders will be satisfied with the 39T/26T range, but it would be nice to simply swap rings rather than the chain rings and the spider if you'd like to go with a lower range after purchase.



Pinkbike's take: SRAM's XO component group is filled with excellent parts that will meet the needs of demanding riders from every discipline, whether they're competitive cross country racers, downhilling privateers, bike park rippers, or anything in between. When used with SRAM's MatchMaker system, the cockpit controls can be tweaked so riders can position everything just where they want it, and the 2x10 drivetrain provides excellent front and rear shifting in almost any conditions and the brakes provide plenty of controlled stopping power when it's needed most. While the group isn't as light as SRAM's race-centric XX group, it's more affordable without giving up a whole lot on the performance front.

In short, everybody should try the XO groupset at some point during their riding 'careers'. Most will be floored by its performance and impressed by its durability and, depending on your style and where you ride, should provide multiple seasons worth of riding with only regular maintenance and little need for upgrading.


Check out the SRAM website to see their entire lineup.

Have you put time in on the XO components? Do you concur with Corey's impressions? Lets hear what you think - put those thoughts down below!

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Reviews and Tech Reviews Drivetrain SRAM Sram X0