Last weekend with the introduction of the new XTR M9100 12-speed groupset came the news that we are getting a new freehub body standard. DT Swiss sent out a quick note saying that most of their Star Ratchet hubs would be compatible with the new XTR, but and it looks to be a bit no more complicated than simply getting a new freehub body.
DT Swiss XTR-compatible Micro Spline freehub body
The new Micro Spline freehub body was ostensibly a Shimano design. But they partnered with DT Swiss during development to make sure that other premium wheelsets could be compatible with the new XTR mountain bike racing drivetrain. DT was chosen on the basis of manufacturing some of the most reliable, high-quality modular hubs on the market, and it certainly doesn’t hurt that they are a huge OEM MTB wheel manufacturer as well.
It was important to Shimano that once the new XTR group came to market, riders would have other wheel options beyond the new XTR hubs. The biggest part of that is really that Shimano elected to make hubs, but not complete XTR wheels. So DT Swiss wheelset compatibility brings a lot to the table for riders (and bike brand managers) not looking to custom build their own wheels.
A welcome surprise with the new Micro Spline freehub is that it was designed to fit 12 speeds and the small 10 tooth cog onto a body that was the same overall width. That in theory means the freehub can be easily swapped out, especially on any of DT Swiss’ higher-end, modular Star Ratchet hubs.
Even though DT is the only company currently authorized to produce Micro Spline freehubs, the reality seems to be that the development agreement between Shimano and DT Swiss appears appeared to prohibit DT from selling the new freehubs individually. In fact, it seems this won’t be a problem as originally suspected, thanks to an update from Shimano!
So while your current wheels with 240s hubs can swap tool free from Shimano 10/11 speed cassette bodies, to a SRAM XD driver body, even to the new Shimano Micro Spline cassette body if you could get one; DT can’t sell you the new freehub on its own…
…only for now, we hope!
UPDATE from Shimano on June 4: Yes, it now appears that the freehubs will be available on their own in time for the Autumn XTR release!
Up Close with the new 12-speed XTR-ready Micro Spline freehub body
Like the SRAM XD driver body, the new Micro Spline body requires a bit of a special touch for DT Swiss, again fitting everything into the same space we’ve been using since before 10 speed mountain bike drivetrains and 12mm thru-axles.
The new Micro Spline gets 22 equally spaced sawtooth-profile angled splines for more positive engagement with the cassette. One of those splines is about double in width and with a larger space to easily align the cassette. Like the previous up to 11-speed design, full-length splines allow the use of either one-piece cassettes, individual cogs & spacers, or some combination therein like the new 10-51 M9100 cassettes.
The new freehub body design still uses a conventional cassette lockring – just scaled down to fit inside of a 10 tooth cog – which also pushes the outer bearing about 5mm back inside the body to allow for the lockring threads relative to XD, but similar to current Shimano 9/10/11.
That also means that the freehub itself is about 1mm longer than an XD driver, although spacing to the outside of the cluster of gears is effectively the same (remember that the SRAM cassettes cover the end of the driver with the smallest cog and the tool interface to tighten the cassette.)
The overall dimension from the hub shell interface to the outside of the axle end cap though, is the same. So no need for any modification of wheel, hub, spacing, or lacing to swap in a Micro Drive body. Like the XD driver, it does require a specific end cap to fit inside the new lockring, but DT will supply that with any wheel, hub, or (eventually) freehub body.
What does that mean for you?
Well, first of all M9100 XTR isn’t going to start rolling off the shelves anytime too soon. Shimano is promising “Fall 2018” availability on the new groupset. That means most of us will have at least until the end of the year to sort out our wheels if we are splurging on new XTR.
It looks like if you don’t want to build wheels with XTR hubs, this fall when you buy a new DT Swiss Star Ratchet rear hub or any of DT’s mid- to high-end wheelsets you will be able to simply select a Micro Drive body at the time of purchase.
For the time being though, it seems that IF you have an existing DT hub or wheel, you WILL not BE ABLE TO buy the new freehub body separately. The workaround may be to purchase the cheapest hub that shares the same size freehub body (say a 350?), get it with a Micro Drive, and swap out onto your fancy custom race wheels?
DT Swiss does look to be the only company besides Shimano itself who will be allowed to produce an XTR M9100 compatible wheel at the time of XTR availability. Much like the previous standard Shimano splined interface though, we can only imagine they will open up the design to other hub producers as well.
Talking with Shimano, they are always cagey, never confirming any future new product development. But much like they more-or-less admitted that a Di2 version of the new XTR groupset could be expected in the future, they also said they are fully behind the new 1×12 drivetrain setup (and indirectly the Micro Spline.) Essentially that was a confirmation to the question asked, “should we expect to see 1×12 trickle down to the likes of XT and beyond?”
So, it looks like Micro Spline is here to stay (or at least once it finally arrives for real this autumn.) And DT Swiss’ race support is already prepared. As select pros start racing on the groupset already – like Jolanda Neff on her prototype Kross that had DT hubs and Mathieu van der Poel on his prototype Canyon which had Shimano hubs – DT is ready to support the rider with Micro Spline freehub bodies as needed.
The rest of us will have to wait.
