Shimano has been teasing the launch of a 12 speed mountain bike groupset tomorrow. There are already some rumours and leaks flying around online…
It had to happen soon. Both SRAM and Campagnolo have released 12 speed groupsets, so it’s no surprise that Shimano’s version is on the way. Shimano have been known as super-late adopters for better or worse for a long time, continuing to produce metal cranks with steel axles, cup and cone hubs, and putting off 1x drivetrains for as long as possible. However, you can (usually) be assured that once Shimano commits to producing something new, it’s going to work and set the industry standards that smaller companies will need to adhere to.
We don’t know much about Shimano’s 12 speed groupset yet but, as you’d expect, the internet is rife with rumours about how they’re going to be fitting an extra cog into our bikes.
While SRAM dishes the largest sprocket over the wheel in order to create the extra space and uses and extra flexible chain, Campagnolo simply makes everything thinner. Shimano have produced an 11 speed cassette which uses this dished sprocket trick in order to allow people to fit 11 speed cassettes onto their older 10 speed wheels, so there’s a chance they’ll be going this way with the new XTR 12 speed too.
Going with a 1x setup can present other challenges, too. In order to create the same wide gear range as a triple chainring setup (or SRAM’s Eagle), it’s necessary to fit a 10 tooth sprocket. As we know, the smallest size sprocket that will fit over a traditional Shimano/SRAM freehub is an 11. That means freehub changes. Taking a look at this chart, it seems like Shimano are going to be committing to doing just that:
SRAM’s XD freehub has been around for a long time now, and many wheel and hub brands offer it as an option. If Shimano chose to use this, it’d mean that Shimano and SRAM wheels and cassettes would continue to be interchangeable. Are they going to? I don’t think so. Take a look at the images from this patent:
That’s not an XD driver. In fact, it looks a lot more like one of these:
The Capreo freehub is an older Shimano design, which lets riders of bikes with smaller wheels go down to a 9t cassette in order to get bigger gears. Most of the sprockets thread onto the freehub as normal, but the smallest ones fit into splines on the next cassette in the ‘stack’. Then, a smaller lockring goes into the middle of the cassette to fasten everything down.
If this is the design Shimano have gone with, it’ll be a departure from the same basic design that has been in use since the ‘80s. Take a look at the chart again – you’ll also notice an 11-speed XTR 10-45 cassette which is also listed as ‘Hyperglide+’. While we don’t know very much at the moment, it seems like lots of people are going to be buying new freehubs or wheels in the next few years if they ‘need’ the latest and greatest.