Shimano M8100 and M8120 Disc Brakes [Rider Review]

Our "Rider Review" article series features the honest reviews from verified purchasers of Worldwide Cyclery. They contain the photos, thoughts, feedback & overall review you are looking for.

There are few things on a mountain bike that are as important as the brakes. Not only is the braking power crucial but also the modulation and feel from the brake levers. Our friend Kevin shares his experience with the Shimano M8100 and M8120 Disc Brakes. Check it out! 

Overview

After being on multiple SRAM Guide RSC’s since they came out and going through the ups and down of the lever issues with those, it was time to try either the G2’s or Shimano XT. I really liked the Guides, especially the pad contact point adjustment and was legit nervous to try Shimano as I always heard they didn’t have any modulation. Even though Worldwide did do this great comparison video, like anything, you really won’t know until you try it yourself. So, I made the decision to try Shimano XT M8100 and M8120 Disc Brakes.

One thing I really like about Shimano brakes is that the 2 and 4 piston brakes use the same lever, so If I ever wanted the 4 piston, I could just purchase the caliper.

I ended up going with a mullet setup (business up front, party in the back), 4 piston up front and 2 piston in the rear. I am a heavy front brake user and didn’t feel I needed the 4 piston in the rear. The first thing I noticed when I opened the box was that the brake line was not connected to the lever. I quickly check to see if they can pre-bled to find out that Shimano has a great quick hydraulic fitting for brakes out of the box. This makes routing the lines a breeze, without worrying about losing hydraulic fluid. I think is a tad easier than SRAM since you need to detach the lever before routing the line through tight spots or internal routing and have to worry about losing fluid and requiring you to bleed the brakes. Setup of the brakes was painless and shortening the disc brake line was easy and the quick fitting worked great. I did not need to bleed the brakes after shortening the lines. Adjusting the lever reach was simple with the adjustment knob and I did not mess with the free stroke adjustment, however I have heard it does nothing. I am also running the brakes with 180 SRAM centerline rotors.

I followed the guidelines from Shimano for pad/rotor burn in and found that they didn’t burn in completely until after a couple 2-hour rides. I immediately noticed the Shimano brakes were more grabby and a little more on/off than the SRAM feel I was used to, which was consistent with what I have heard. I have always run the RCS pad contact point adjustment as close to the rotor as possible, so I preferred a short free stroke and this is how the Shimano brakes feel. However, I think that modulation is a skill and not something your brakes should do for you. I have come to really like the feel of these brakes as you can use less lever pressure to obtain the similar level of braking power, compared to the Guides. You can also lock the wheel up very easily, which is great if you are looking to scrub some speed quickly (without skidding, of course). Honestly, I don’t notice much difference in power between the 2 and 4 piston and the 2 piston on the rear seems plenty powerful. I have noticed some lever feedback under consistent hard braking, which is something I did not experience with SRAM brakes. However, it was very minor.

Final Thoughts

After only a few rides, I knew I made a good decision getting the XT brakes and I adapted to the difference in free stroke / braking feel after 2-3 rides. I am looking forward to seeing how these brakes perform over the next year.