For e-bikes and aggro shredders.
What’s a 4-pot disc brake you may ask? Basically there are two sets of pistons (so four in total) instead of the more usual single set of pistons.
Why go 4-pot? More braking power. But perhaps not as much as you may think; Shimano claim the new ceramic piston M8020 4-pot XT brakes offer 20% more power over the 2-pot M8000 version. Perhaps just as important is the better handling of heat. 4-pot brakes often deal with – or prevent – overheating better than 2-pots.
Why not go 4-pot? They’re heavier. And they can be a bit of pain to align correctly with the rotor. A drag-free 4-pot brake is quite an achievement in our experience.
4-pot Shimano brakes are a rarity outside of their downhill-centric Saint range. Indeed there hasn’t been a 4-pot non-Saint Shimano disc brake announced for almost a couple of decades.
So why now? In a (hyphenated) word: e-bikes. Electric mountain bikes are heavy and they require a lot of stopping. And the sort of super long sustained descents that some e-riders are doing, now that they have the power-assistance to reach places and heights they previously couldn’t, cause regular disc brakes to boil over and fade.
Of course, you don’t have to put them on an e-bike. If you just want a flipping powerful, fade-resistant brakes on your regular mountain bike, go for it.
The new 4-pot M8020 callipers can be retro-fitted to existing M8000 XT brake levers. They will also be coming supplied as a fully bled system including a lever but we don’t know if the lever will be much (if at all) different from the current M8000 lever.
New 165mm Shimano XT cranks too
Another one principally brought about by e-bikes, which seem to have more issues with pedal strikes than most regular bikes due to a common design theme of low-BB-for-stability geometry.
There’s also the theory that e-bikes engender a higher cadence than regular bikes and short cranks do help with that. E-bikes don’t need to leverage power of longer cranks so why not run short cranks really?
Again, they aren’t explicit to e-bikes. If you want some shorter cranks for whatever reason, you can now opt to go with XT.