Curtis Keene dropped by the Pinkbike HQ with his Specialized Enduro S Works Carbon that was equipped with the prototype 9 - 36 tooth spread, 10 speed cassette.
The last few seasons have seen the mountain bike drivetrain make what can only be described as a meteoric jump on the evolutionary ladder, especially when comparing its latest progress against the previous decade's worth of advancements. People have long been playing around with gearing combinations that suit their terrain, take many riders from B.C.'s North Shore region who have been running modified double chain ring cranksets since mountain biking's early days, but manufacturers are now stepping up to the plate more so than ever with options for everyone from single speeders to those who want just the right gearing spread for their local terrain and style. Just take a look at the super trick 1 x 6 gearing using a 9 tooth cog that you saw on the Team Monster Energy - Specialized bikes ridden by Brendan Fairclough and Sam Hill. Similarly, companies are also working on a large spread cassette, shown here for the first time, for XC use that also uses a 9 tooth cog on the high end.
It's easy to spot the difference between the new large spread prototype cassette (shown above) and a standard version when looking from this angle.
The spread above uses a 36 tooth large cog on the low end and a tiny 9 tooth cog for the highest gear. This is where the ingenuity comes in, because as anyone who's had their cassette off may well know, the smallest cog that would previously fit would be an 11 tooth version due to the freehub's diameter. This is where DT Swiss steps in with a custom made freehub body that accepts a smaller cog. As of right now the actual design of the freehub remains unknown, but to get an idea of what it may look like, have a gander at Shimano's commuter intended Capreo group that also uses a 9 tooth small cog. I'm betting that the DT Swiss freehub is also stepped and that the bottom few cogs are a single unit. The very special freehub body has been manufactured by DT Swiss solely for the R & D that Specialized is doing for this project, you won't see it anywhere else anytime soon.
The 9 tooth cog is held on with a large lock ring on this prototype version.
The new gearing range made possible by these large spread cassettes may not get the press that a new bike would, but this is big news for a lot of riders who want to simplify their drive train by running a single chain ring, but still want a usable gear selection. So what does all this talk mean? Well, the real story here is the addition of the 9 tooth cog to the mix. The 9 tooth cog allows the rider to use a single smaller chainring (say a 28 or 30 tooth ring) as opposed to a double ring setup to eliminate all of those redundant gearing options, but also even broaden the gearing range. For example, a common 24 tooth ring and 36 tooth cog combo gives you a rollout of 1.52 meters, but a 28 tooth ring and 36 tooth cog would give you 1.67 meters... a pretty damn close easy gear. But on the other end a standard 32/11 combo gives you a max rollout of 6.26 meters compared to a 28/9's 6.7 meters. At this point in time Specialized is the only company that is pursuing this gearing concept, but it makes enough sense that we could possibly see that change in the future.