Find out everything you need to know about the Shimano 12-speed family!
All three cranks still use a 24mm spindle, but Shimano now use a direct mount chain ring. You can get an eMTB specific ring in 34, 36 or 38t as well! Shimano XTR has options from 30-38t, Deore XT has 28-36t and SLX has 30-34t. Remember, they are all compatible if you're seeking out a bit more range. Deore XT and SLX use a 2-piece ring for an alloy carrier with steel teeth.
The 2x options are still direct mount as well, and with Deore XT and SLX there are 3 Q Factor widths for three chain lines – although just 2 chain line options if you're looking at a 2x setup.
XTR is the most different here as the construction makes it a whole lot lighter yet still super stiff.
Chains and cassettes
Along with the chain rings, this is where the action is. All three groups share the Hyperglide Plus system, which is specific tooth profiling to match the chains for way faster shifting up and down the cassette, especially under load. If you consider this was already optimised for down shifts to large sprockets, what Hyperglide Plus does is helps the chain move to a smaller sprocket. Instead of the derailleur knocking the chain off and guiding it to the smaller sprocket, the shaping on the teeth and chain moves it over in far less of a pedal revolution. Even better, it engages best under load.
So, go ahead and shift while climbing, or getting out of the saddle. It just gets better! The cassette ranges are the same, but XTR has more alloy sprockets for the small gears, and the middle range is Ti. Deore XT has two alloy sprockets and SLX keeps it just for the big one. The chainrings have been designed to work with the chains so if you opt for a non-Shimano ring you might lose some of the chain security.
All the chains are 12-speed specific, and the XTR model has a full SilTec coating for improved shifting and durability. Also, the hollow pins make it lighter and stronger, as the peening is more effective. Peening is how the ends of the pins are flared, to hold the plates in.
The pedals have been refined, mostly to optimise foot contact and pedal size. The aim is to increase comfort and clearance. This is the same for Deore XT and XTR, and there are also two platform sizes for the flat pedals.
Hubs and wheels
This is a big change for Shimano, as while they are still cup and cone for endless servicing and adjustment, the two plates engage for a much faster engagement – you're looking at about 7 degrees. The XTR hubs are lighter, the SLX hubs are heavier – this is down to materials and production.
Deore XT hubs are available in normal through axle, Boost and Superboost, in centrelock configurations and 28 hole and 32 hole. There are straight pull options for XTR and Deore XT as well.
There are two Deore XT level wheel sets, one for regular trail use and a 30mm internal alloy rimmed model for aggressive trail use. It's s zero dish tubeless wheel with wide hub flanges and 28 J-bend spokes – and we can't wait to test a pair.
The big talking point here is Microspline, the new freehub standard that is required for Shimano's 12-speed cassettes. It is a reduced overall diametre to allow the 10t sprocket. Right now this is still a catch with a Shimano 12-speed upgrade. Given the ride of the Deore XT hubs I'd build some wheels on them in a flash. And with the aggressive trail wheel, normal trail wheel and a MT620 wheel set available from Shimano, there are pre-built choices from Shimano. So far though, only riders with Industry Nine or Dt Swiss hubs (or designs using the DT Swiss hub internals) can upgrade their freehub to Microspline. We hear that White Industries have an option that works around Shimano's design and is compatible, but when hub makers like Hope, Stan's NoTubes, Novatec and more can use the design the 12-speed upgrade will be a lot smoother for more riders.(Hope have since been granted a licence to produce Microspline compatible hubs)