FIRST RIDE - Queenstown, New Zealand
SRAM X01 DH
Racers have been asking for a production downhill specific group with less gears for a long time, and 2014 will be the year that those requests are answered. SRAM's new X01 DH offering combines both existing and brand new components to create a drivetrain that has been designed specifically for the needs of downhillers. Available this coming April, the X01 DH group includes a crankset, modified shifter and derailleur, and an entirely new 10 - 24 tooth spread, 7 speed X-DOME cassette. You'll also need an XD driver body and 11 speed chain because the group uses the same 11 speed spacing as XX1 and X01. Don't want to spring for a complete drivetrain? SRAM will also be offering a 10 speed version of their new X01 DH derailleur that will work with any 10 speed cassette and SRAM shifter.X01 DH Explained
We flew to Queenstown, New Zealand, to spend a few days on the new X01 DH group and to learn the ins and outs of its design.
The new downhill specific group
uses the same technology as SRAM's XX1 and X01 drivetrains, which shouldn't come as a surprise given that both of those groups can trace their roots back a decade or so to what was originally a prototype derailleur intended for downhill use. It's only now, many years later, that SRAM is revisiting those intentions. Why now? ''What we looked at was how we could make a drivetrain work better on a downhill bike, and if we're completely honest with ourselves, current downhill bike drivetrains don't really work that great,
'' Chris Hilton, SRAM External Drivetrain Product Manager, told Pinkbike. ''They work acceptably, and they do shift, but there's a lot of things that cause them to shift funky. The axle is moving upwards and backwards far more that on other types of bikes, and every single downhill bike is different in this regard, all while powerful riders are putting out huge watts while sprinting and pushing buttons, hoping that it changes gears. That's not exactly a recipe for success.
'' SRAM clearly believes that they can come up with something better than what's currently out there, and that is exactly what they set out to do, despite the marketplace for a downhill specific group clearly being much smaller than a drivetrain that would be put to use on a trail bike.
We have to pick our path. Are we going to go down, get cheaper, and make a bunch of X7 stuff? At some point, yes, we'll have to try and continue to reduce the price of our one-by groups. But are we going to try to take our one-by technology and use it in other places where it's useful? Yeah, we are, and that's what we're doing today. X01 DH uses all of the same technology that is found in XX1.
- Chris Hilton, External Drivetrain Product Manager
X-DOME Goes 7-Speed
The investment put into X01 DH, while not small by any means, was benefited by what SRAM calls their ''core technology', much of what makes XX1 and X01 tick, already being proven to function well. That includes their Type 2 clutch derailleurs, X-Sync chain ring tooth design, and both the XD driver body and X-Dome cassette that can be found on the new downhill group. Hilton told us that it is only the success of those two groups and the core technology in them that has allowed their engineers to pursue a production downhill component range. ''We developed our core technology, and we have to decide what we're going to do with that technology,'' he explained. ''Of course we could go cheaper. We could make X7 one-by and all these things, and that is one path to take. A reasonably successful path to take commercially. Or we could take the philosophy of the one-by drivetrain and instead of going down with it, we could go across into other categories.''
SRAM's X-DOME cassette is arguably the crown jewel of both the XX1 and X01 component groups, with its extensively machined away steel construction and aluminum large cog / backplate making for an extremely light finished product. The very same manufacturing methods have been used to create the 7 speed X01 DH MINI BLOCK cassette, with SRAM saying that the finished product weighs just 136 grams. That's a touch lighter than SRAM's top tier eleven speed RED cassette, and thirty three grams less than Shimano's Dura-Ace offering, although having four less cogs despite sporting a similar top and bottom ends obviously works in the MINI BLOCK's favour. Weight isn't the real story here, though, with the relatively large jumps between those seven cogs, yet featuring the same spacing as their 11 speed blocks, counting for much more than a handful of grams being shed. How so? SRAM says that they have data showing that racers are double shifting - grabbing two gears per shift - over fifty percent of the time when running a standard road bike cassette, something that points towards said cassettes having far too closely spaced gearing jumps. ''They were designed for guys wearing lycra who are trying to maintain an optimum and very specific cadence to keep their speed up and be more efficient,
'' says Hilton. ''That's not the same needs of a downhill racer, or even of a dirt jumper, who need to accelerate and decelerate quickly.
These road cassettes are being used for their top and bottom end ranges, not the small jumps in between, as large cogs simply aren't required if you're riding a downhill bike as it was intended. The obvious answer was to create a cassette that offered not just the overall range that would makes sense but, more importantly, much more useful jumps between each cog that wouldn't require a racer to double or triple shift. It's that double and triple shifting under extreme loads, especially common during a race run, that can cause both broken chains and poor shifting. There's another factor here, Hilton says, with the fractions of seconds that are lost while slightly easing up on power during those double shifts adding up over a race time, a factor that he told us is trimmed down by turning two shifts into one. No, that's clearly not going to be a super important point to a casual rider or sport-class racer, but consider that the sharp end of a World Cup downhill field is often on the same second and you can begin to see where he is coming from. SRAM tested and settled on a 10 - 12 - 14 - 16 - 18 - 21 - 24 spread, as well as an integrated spoke guard that attaches in the same manner as the large 42 tooth cog on their XX1 and X01 cassettes. The $303 USD cassette is also compatible with the same XD driver bodies that their 11 speed cassettes require.
You're putting the drivetrain in a really extreme environment. Just look at the tracks that are being ridden, how fast they're going, and how much the bikes are changing, and we're trying to build a drivetrain to work well there. Up until now we've just been piecing drivetrain parts together. They work; they function. But can they be better? Yeah, they can be better.
- Chris Hilton, External Drivetrain Product Manager
7 Speed Specific X01 DH Derailleur
It became obvious that SRAM was working on a downhill specific drivetrain when we first spotted a prototype derailleur and what looked to be a compact X-DOME cassette on the back of Aaron Gwin's Specialized Demo 8 Carbon race bike during last season's Fort William World Cup race. Besides a shorter cage, the clutch equipped derailleur appeared to resemble a production unit, and we speculated at the time that it could be the predecessor to either the yet to be released at the time X01 derailleur or a more gravity orientated setup. As it turns out, the sighting was the first public showing of what to expect of the X01 DH derailleur pictured here.
So, what exactly is different between the XX1 or X01 derailleurs and the new X01 DH model? The most obvious difference is the shorter cage, with its downhill intentions meaning that it doesn't have to deal with the added chain length that a larger 10 - 42 tooth spread cassette requires. SRAM will offer the $277 USD X01 DH model in two cage lengths, a short and a medium, that will cover the chain growth figures of every downhill bike on the market. Many bikes will be able to use the short cage model, but bikes with more a more rearward axle path than usual, such as Canfields, should be fitted with the longer of the two options.
Less obvious are some changes that are hidden out of sight, including a longer low-limit screw, a differently shaped low-limit screw stop, as well as a different rearward stop that better match it to the compact 10 - 24 tooth cassette. Given that SRAM's top tier XX1 single ring group can trace its roots back to the development of a downhill specific derailleur ten years ago (pictured above), it isn't much much of a stretch to see the that technology applied to a modern component group for the same intention. ''The idea of a one-by, downhill specific derailleur ten years ago was deemed to be unnecessary.'' Hilton told Pinkbike. ''That early prototype sat around collecting dust on an old specialized Demo with an eight-speed cassette because there was no application for it. But, times were changing, and we saw people starting to ride one-by-ten.'' As the success of their XX1 and X01 groups began to prove that it isn't just out and out racers that wanted to use the group, SRAM began to consider other applications that saw the technology come full circle back to its original intentions.
7 Speed Specific Shifter
Shifting the chain across the seven cogs of the MINI BLOCK cassette could actually be done with a current 11 speed shifter due to it using the same cable pull ratio and the cogs featuring the same spacing, but that solution wouldn't be ideal given the four extra clicks on one end of the spectrum. Instead, SRAM modified their latest fourth generation shifter with a revised stamped steel ratchet wheel with four less teeth, a relatively simple way to go about it. The shifter sports the same ergonomics as found on SRAM's other offerings, with an adjustable thumb lever, two-position mounting, and is also Matchmaker compatible. Cable changes are accomplished in the same manner as in the past, with a removable aluminum cover hiding the revised internals and cable port. The shifter will retail for $143 USD when it becomes available in April.
Carbon Arms and X-Sync Chain Rings
Many readers are likely familiar with the carbon fiber X0 DH crankset, and it is that very setup that you'll find carried over to the new X01 DH group. That means that they'll still be available in 165, 170, and 175mm lengths, all with the same aluminum pedal insert and sub-800 gram weight including the bottom bracket. What has changed, though, is the inclusion of SRAM's X-Sync chain rings that we've begun to see both downhillers and freeriders use in competition, with and without a chain guide. The rings will be available in 30, 32, 34, and 36 tooth sizes to fit the drive side crank's 94mm BCD. GXP compatible setups will retail for $315 USD, while BB30 version will go for $347 USD.
10 Speed Option
The majority of downhillers out there are running ten speed setups on their bikes, and SRAM knows full well that many of them won't be keen on purchasing an entirely new drivetrain, or at least a derailleur, X-DOME cassette, and the required shifter in order to use the latest 7 speed setup. A much less expensive option, although one that won't work with the trick 7 speed cassette, is the new 10 speed X01 DH derailleur. It features the same construction as the 7 speed model, sans the reworked limit screw and screw stop changes. The biggest difference between the two, though, is the cam that the shift cable wraps around that provides the correct amount of leverage to make it 10 speed specific. This means that the 10 speed X01 DH derailleur isn't compatible with both the 7 speed and 11 speed shifters, but will work with both 10 speed trigger and Grip Shift options.
While it retails for the same $277 USD price, the 10 speed version can be bolted onto any bike that uses a 10 speed cassette and shifter, which is the large majority of machines out there.
FIRST RIDE - Queenstown, New Zealand
RIDING SRAM'S X01 DH
Our introduction to the new X01 DH group was split between time on two bikes, a Devinci Wilson Carbon and an Intense 951, and the three days of ride time included two in Queenstown's Skyline Bike Park and a helicopter assisted shuttle to the top of a local peak. We can't reiterate enough that those three days shouldn't be taken in any way as time enough for us to come up with a thorough review, so think of this as more of an introduction with first ride impressions included than a true in-depth evaluation of how SRAM's new downhill specific group functions. With that disclaimer out of the way, lets talk about our first impressions of X01 DH.
SRAM's big storyline with X01 DH isn't specifically that it's 7 speed, but that the jumps between gears have been designed to be more useable and functional for downhillers. That approach, with a 10 - 12 - 14 - 16 - 18 - 21 - 24 spread on the cassette, is certainly noticeable when in action, but it isn't quite as cut and dry as you might think. Some of our initial time on the group was spent riding trails that we'd label as being either quite steep or very smooth and fast, meaning that it was more a matter of choosing a gear at the top of the run and dropping in than actually slowing up and then accelerating out of corners. Having said that, it was still quite obvious that the 7 speed setup provided a completely different type of performance than what you'd find from an 11 speed road cassette. No amount of back pedalling over rough terrain, even when shifting like we forgot how to control the thumb on our right hand, was able to really upset the system. No skipping. No strange behaviour from the chain. Nothing. The setup was also as quiet as we've come to expect from a clutch equipped drivetrain, although the bike's Truvativ X0 chain guide also certainly helped matters in this regard. Shifter feel is very SRAM-like, as you might assume given that the 7spd X01 DH trigger is a modified version of what the company already offers, and this means that you can expect positive and tactile action at the handlebar.
It was when we left the bike park and ventured onto more varied terrain that the merits of X01 DH became much more noticeable. After a short but incredibly scenic helicopter shuttle to the top of what could be the most beautiful location that we've ever ridden a bike, we dropped into a trail system that included pretty much any and every sort of terrain imaginable. It was here, on trails that saw us go from doing high speeds to being hard on the brakes for a corner, where X01 DH's gearing was most noticeable. The result? Less shifting, with a single stab of the thumb paddle seeing us shifting to an easier gear faster than we've become accustomed to with a standard cassette. This is down to the larger than standard jumps between each cog, and it is something that won't just be a benefit to racers when having to drop anchor for a corner and then accelerate out of it, but also for those dreaded moments when a corner is blown and he needs to get back on the power to make up lost time.
The market for a 7 speed downhill specific group is much, much smaller than components intended for any other mountain biking discipline, but that certainly doesn't mean that a group designed for exactly those intentions shouldn't be offered. In fact, given that downhilling is arguably the one style of riding that puts the most demands on components, it makes sense for a group to be designed specifically for it. Do the current drivetrains being used on downhill bikes work? Of course they do, although a more specialized approach to problem looks like it could very well offer some real advantages, especially in a race setting.
Action photos by Adrian Marcoux