SRAM XX Mountain Bike Component Group Unveiled!

While we knew it was officially going to be released, we finally have some official pictures from SRAM of their new 2×10 “XX” mountain bike component group.  As would be expected from a top-of-the-line race-oriented group, it’s light…sub 2300g to be exact (not counting suspension components), making it at least 400g lighter than a full Shimano XTR or SRAM XO group. There’s a full component weight list after the break.

Granted some of that weight savings is coming from the lack of a granny ring, but there are some other major technical innovations that contribute to the feathery-ness.  For instance, the new “X Dome” cassette (above) modifies the SRAM RED Power Dome road cassette by drilling out much of the metal space between gears.  Since RED cassettes tend to collect mud, they couldn’t translate that lightweight design directly, and this heavily machined beauty is the result.  Click the thumbnail below to see the backside close up.

  

Hit ‘more’ for additional photos, specs, weights, prices and more…

Across the group, carbon, magnesium, aluminum and titanium make up virtually all of the hardware, and almost everything is mounted or adjusted with a T25 Torx bolt.  This makes service and adjustments easy, and lightens the load for epic rides since one tool covers pretty much anything you’d need to work on trailside.

BOTTOM BRACKETS:

SRAM will offer a number of options for bottom bracket / crankset spindle, giving the XX platform the flexibility to go on a number of frames.  The options are:

• GXP – standard 24mm – steel spindle – standard thread-in
• GXP – standard 24mm – steel spindle – press fit (Shimano 86mm BB press fit standard)
• BB30 – 30mm – aluminum spindle – machined shell w/ clips and press fit bearings
• PressFit 30 – aluminum spindle – self-contained bearing shell system

The PressFit 30 is the real innovation for the bottom bracket, if you consider self-contained bottom brackets an innovation…  It’s fully enclosed, with bearings set into a resin cup.  It’s well sealed, and the entire unit presses into a standard oversized BB shell.  The benefit is it doesn’t require the exact tight tolerances of bearing systems that press fit into a frame.  The PressFit 30 promises quiet, creak free performance.  All versions use hybrid BlackBox ceramic bearings. 

CRANKSETS:

The crank arms are a unidirectional carbon fiber wrapped around an aluminum spine, similar to RED and Noir.

Besides the obvious lack of a third ring, there are four major new features of the SRAM XX crankset: A narrower Q Factor, slimmer chainline, tapered chainrings and a patented tooth ratio on the rings.

The “standard” version will have a narrow Q-Factor of 156mm, which is 17mm narrower than a standard crankset, making it feel more like a road bike.  This set up will be available with both standard GXP and BB30 spindles.  This is one of the biggest benefits of a “2x” system, allowing for a better pedal stroke feel.

But, many frames use chainstay designs or suspension swingarm designs that won’t accept the narrower Q Factor, resulting in cranks that wouldn’t spin all the way ’round.  SRAM’s solution was to develop crankarms that jut out a little further from the spider, allowing the arms to clear frame elements of many more (but not all!) frames.  The wider options include 164mm BB30 and 166mm GXP cranksets.

Next, the chainline is slimmer.  The distance from center of ring to center of ring is 49.5mm, down from 51.5mm for Truvativ Noir crankset.  The slimmer chainline allows the full range of the cassette to be used from either chainring.

The chainrings are actually a little thicker at their base than Truvativ’s normal 4mm-thick chainrings, tapering from 6mm at the bolts and getting a bit thinner toward the teeth.  This, combined with the tooth ratio we’ll explain next, help guide the chain from the big to the small rather than just dropping it.

Lastly, SRAM pulled from the patent archives to use a 2:3 tooth ratio, offering three gearing options: 26/39, 28/42 and 30/45.  During the development process, an engineer realized there was a patented system that allowed for ultra smooth shifting by using those specific chainring combos and specific pin and ramp placement.  Basically, it has eight pin/ramp placements, four pick up points and four release points, that line up with crank arm position depending on whether it’s an upshift or downshift and keeps the chain securely hooked on 13, 14 or 15 total teeth (depending on ring combo) on both chainrings until the shift is complete.  The claimed result is the ability to shift either direction under full pedal force.

Put it all together and you have what SRAM calls X-Glide, and it’s available in 170mm and 175mm arm lengths.  The big ring uses a 120mm bolt pattern, the small ring an 80mm pattern, and neither set of bolts use nuts; the outer bolts thread directly into the big ring itself, and the inner bolts thread into the spider.  SRAM says its their best shifting front rings ever.

CHAIN:

At launch, there is no SRAM XX specific chain.  You’ll be able to use either of SRAM’s top 10-speed road chains with the group.

CASSETTE:

The X-Dome cassette is machined out of nickel plated 4130 chromoly for all but the smallest and largest gear.  The smallest is aluminum and is separate (ie. replaceable) from the rest.  The cassette body is mated to an aluminum skeleton on the backside, which includes the largest gear. Options include an 11-32 and 11-36, the latter of which offering just about as wide of a gear range as you’d need, depending on your choice of chainring sizes.  Even with the extra cog, it weighs in more than 40g lighter than an XTR cassette.

The tooth and ramp profiles are also heavily worked, also getting the X-Glide branding, keeping shift performance in line with the new chainring patterns in the front.

FRONT DERAILLEUR:

You think the cranks had a lot of options?  The front derailleur, which is SRAM’s first true top-level front changer, will have options for high mount (above), low mount and direct mount (left). The High Mount versions get a sweet new steel band clamp that will work better for carbon frames, both because it’ll conform better to shapely tubes and exert less directional clamping force in any one given direction…which can damage a carbon tube easily if over tightened.  Take all that, then add top pull and bottom pull options plus various clamp sizes and you end up with more than 40 configurations.

The XX front derailleur uses forged 6061-T6 aluminum body arms with a stainless steel cage designed specifically around the 2×10 gearing.

REAR DERAILLEUR:

The SRAM XX rear derailleur is based on the X0 model, but gets a full carbon fiber pulley cage with hybrid BlackBox ceramic bearings in the pulleys.  The cage has been extended to 93mm to accommodate the 36-tooth cassette. It also gets a magnesium forged linkage body and rear fin (with integrated cable guide), and the cable bolt has moved from the outer link to the inner link, putting it in less potential contact with trail debris.  A titanium spring and ti / aluminum hardware round out the tech features.

As far as shifting goes, the XX shifters and derailleurs borrow the Exact Actuation movement from SRAM’s road groups.  That means a) that the cable pull corresponds to exactly the same amount of derailleur movement, and b) that SRAM’s road levers and derailleurs will be compatible with the XX shifter and derailleurs.

It also means that older / other SRAM mountain bike shifters and derailleurs won’t be compatible with XX stuff.  Me thinks this will be the way things trickle down in the future, ultimately making all SRAM road and MTB bits work together.  From SRAM’s perspective it makes a lot of sense, allowing manufacturers and consumers to mix and match parts for cyclocross, touring and commuter bikes.

One rumor that’s been tossed around about XX was the potential use of a DoubleTap shifting system.  I’m pleased to report, that’s not the case…Personally, I just don’t think that system would translate well to a set up that’s used on rough trails where thumbs are bouncing around.  I am curious to see if they come out with an XX twist shifter in the future…

SHIFTERS:

Like the XO, the XX shifters use a dual lever, aluminum-and-carbon clamshell design with a position-adjustable thumb lever.  Where it becomes XX is with a 3mm shorter  thumb (cable pull) lever, which is now all carbon.  The result is a super light shifter pod weighing in at just over 180g per pair…about 40g less than XTR or XO!

BRAKES:

Using the Avid Elixir CR as the base, SRAM stuck with a two-piece piston, saying it was lighter and stronger than a forged design. 

Changes from CR to XX include some of the things we predicted after seeing Julien Absalon’s winning bike: A slimmer Taperbore master cylinder, the reworked Matchmaker clamp (more on that later) and different reach adjustment.  Now we have the details to back up our spy work.

The lever reach adjustment now requires a tool and is adjusted via a small screw between the lever and the grip (facing out).  Pad contact adjustment is still tool-free.  The carbon lever dropped from 11g to 8g, which is a significant percentage, but not a lot of grams.

The pistons and rotor saw more remodeling for XX than the levers.  The piston body is a new forged magnesium design with pad access on the top, and the rotors use a stainless steel rotor with an aluminum spider.  All in all, it drops the weight to 288g for a 160mm, post mount front brake set up, putting it well below most top-of-the-line offerings and within fighting distance of Formula’s R1 set.  A 140 (rear only) and 185 diameter rotor will also be available, 6-bolt ISO only.  Centerlock fans will need an adapter.

MATCHMAKER X:

The new MatchMaker X uses a hinged “U” clamp rather than a two-piece clamp like before.  With everything outiftted on it, it really is a cleaner, more elegant look, and it adds horizontal adjustability to the shifter placement, allowing you to better personalize the fit and feel of your cockpit.  Shown above the preceding “Brakes” paragraph, it has the new XX brake lever, shifter the XLoc all attached.  Like its predecessor, it can be mounted on either side, so there’s only one clamp for left and right.

 

XLOC HYDRAULIC LOCKOUT AND XX SUSPENSION FORKS:

Perhaps one of the coolest new features is the XLoc hydraulic fork lockout that mounts directly into the new MatchMaker X bracket.  It operates much like a click pen; push it down to engage, push it again to release.  It saves about 60g over a cable actuated system, and it’ll have an external Floodgate adjustment dial built in to control big hit blowoff limits. The potential downside is if the hydraulic line loses fluid or gets cut, it’ll revert to the locked out position.

While not considered part of the XX component group, SRAM has given several of the RockShox forks XX monikers.  The differences between the XX versions and their regular counterparts largely boil down to coming out of the box with the new XLoc hydraulic lockout mechanism already installed.  More info on the new 2010 SID World Cup fork is on a recent post, here.  There will be an XX Reba option for 29ers and XX Reba and XX Revelation models with thru-axle options.

 XX Suspension Forks include:

WEIGHTS:

PRICING (USD):

If you’ve got a cheatin’ heart, Velonews and BikeRadar also have some pics and first impressions.