XDR is here, so what do you need to know?

With Sram's introduction of their new Red Etap AXS group, they also announced their new XDR freehub body.  XDR isn't actually new though: the first place we remember seeing it was on Sram's 900 series of hubs, which came out back in 2016.  When asked about the new driver body, which a the time had no apparent use, we were told that it would allow for the development of a 12 speed road drivetrain at some point, and now that has arrived!

So what's the actual difference between an XD and an XDR driver?  The latter has splines that are 1.85mm longer, making the driver body that carries the cassette effectively longer (the same as an 11-speed road Shimano-style driver, but more on that in a moment).  If you want to run an 11 or 12 speed mountain cassette, you just need a 1.85mm spacer behind it on the XDR driver, and you're good to go.  It's worth emphasizing, however, that while the freehub is very similar, it is longer, so it needs a hubshell that's designed for it.  This is one reason that it Chris King is offering it only on their road hubs, which are built for a longer 11-speed road Shimano style freehub body to begin with.  Since White Industries makes all of their hubshells slightly narrower to fit an 11-speed road freehub, the XDR freehub will work on all of them. 

Because all hub brands have approached freehub and hub design in general in their own way, it's hard to make any blanket statements about compatibility across multiple brands, but here's what we can say about the brands we carry:

• Chris King R45, R45D Gen. 2, and R45D Centerlock hubs will be compatible with Chris King's new XDR driveshell, and conversion kits, as well as complete hubs should be shipping around the middle of March, 2019.  Currently there is no word on possible compatibility with other Chris King hubs.
  
• White Industries has an XDR driver that is compatible with all of their recent hubs.
• Onyx Racing Products is working on an XDR driver, and while we expect that it will definitely compatible with their road hubs, we don't have any word on compatibility with mountain hubs.  We'll keep you updated as new developments arrive on that front.
• Phil Wood currently doesn't have plans to make an XDR driver.

Beyond this basic run-down, we're sure there will be questions, and we'll be here to answer them!