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.
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.
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
