Let’s cut straight to the chase: do these brakes have a wandering bite point? The answer is: they did, but now they don’t.
To elaborate, the front Shimano XT M8100 disc brake has always been fine, but the rear brake quickly developed the infamous wandering bite point that upper-level Shimano brakes have unfortunately become known for in recent years. The solution, no matter what you may read online, is a comprehensive bleed.
The only way to do a wholly comprehensive air-ridding bleed of Shimano brakes is to completely remove the bleed nipple assembly from the caliper and do a top-to-bottom gravity bleed while cradling the caliper in an old rag and rotating the caliper in every plane possible – ideally with the whole brake removed from the bike (not easy if your bike has internal hose routing). Once you’ve gone through this rigmarole, the brake should perform fine for a few months. Mine has been fine since. Touch wood.
When working as they should, the XT disc brakes are lovely. Much like everything else XT-flavoured from Shimano, the experience is all about ‘feel’. Maybe I just have Shimano-shaped fingers, but I can never get comfy when using non-Shimano brake levers. All other brand brake levers just feel a bit too chubby and/or hard-edged. Which is fine if you like it that way.
Anyway, back to the feel. Basically, you can clearly feel the instant where the pads meet the rotor. There’s a definite ‘thunk’ sensation, but there is no grab or snag sensation. Which makes them great for movements that are less about slowing down and more about bike handling. The rotors (not included and £31.99 for 203mm size) also play a part in this impressive level of feedback and control. There’s no pulsing of power. In this sense they make for ideal trail-riding brakes where the impressive level of interaction really improves flow and fun. All-or-nothing gravity fiends should look for something with more top-end power, though.
Living with them, post-bleed faff, has been easy. The pistons have been no trouble and there has been none of the resistance or uneven stickiness that other brands’ pistons exhibit when it comes to replacing worn-down-to-the-backing-plate pads.
So the question is… are Shimano XT M8100 disc brakes worth the painful bleed regime? We’d say no. We’d go for Shimano’s Deore M6000 series brakes instead.