There are few component choices as polarizing as the brakes you run, and people tend to develop lifelong affiliations with their brand of choice, never trying their hand at the competitor’s offerings. Despite the vast array of options on the market these days, nobody can claim the consistent presence and performance of Shimano, who have long held their ground as some of the top performers. But with so many competitive offerings available to today’s riders, does the old guard still hold up?
The touchpoints and features are standard fare for Shimano at this point, and the newest generation has all the little refinements one might expect. The reach-adjustable 2 finger carbon fiber lever makes use of their Servo Wave tech to control the delivery of power into the system. It mounts to the bar with their I-Spec EV clamp, which integrates shifter and dropper levers neater than ever, and there’s a free-stroke adjustment screw to dial in the feel. Down at the Mono-Body one-piece caliper, there are four ceramic pistons to deliver the power to the pads. The Ice Tech finned pads help to cool the system down in use by maximizing the surface area, ensuring the mineral oil that’s contained within doesn’t overheat.
As it’s been a few years since the M9120s were released, and this set has been mine since day one, this article will dive more into the long-term ownership and hacks that make these brakes not only endure abuse but remain some of the best brakes you can buy, ride after ride.
THE DIRT
My time on the XTR M9120 brakes started out as a standard Shimano affair: brand-name finned pads, brand-name IceTech rotors, all as the engineers in Sakai intended. In this form, especially when new, the brakes are fantastic. Sharp bite point, tons of power, and comfortable modulation once you’re used to the light feel.
Like anything I own for a while, it didn’t take long before the modifications started. First off were efforts to abate the dreaded wandering bite point that has plagued Shimano brakes for a few generations, occurring often enough to become somewhat of a meme in the bike industry. It took about a year of heavy use before I experienced this, with fewer bleeds than these things deserved, and some pretty mixed trail conditions thrown in for good measure.
There are a lot of theories thrown around as to why this bite point problem occurs, but you know it when you feel it, and it can really harsh your mellow. The first line of defense are lever bleeds – quick, dirty, and pretty effective at making a Shimano brake feel snappy again, for a short while. These are especially useful as your pads and rotors wear, since the finite volume of fluid in the brake is trying to take up more space than it was initially meant to. Adding more fluid with a lever bleed improves that equation, mitigates heat buildup, and gets rid of any small air bubbles that may have found their way in. Keep in mind that you’ll likely need to remove some when it comes time to install some fresh pads though.
Another little annoyance that many people pick up on is the noise from Shimano’s finned brake pads. How they haven’t fixed this little detail, or even let it get past their initial testing, I do not know. Luckily there’s an easy fix that silences them perfectly. Pop those puppies out, grab a roll of mastic tape, cut four 5mm wide strips of the gummy black stuff, and stick it to the underside of the fins. Reinstall, and ride in blissful silence.
Over the past few seasons, I’ve experimented with lots of aftermarket pads from different manufacturers and have been impressed by quite a few. MTX Gold pads killed it through a harsh PNW winter, providing a ton of bite once heated up. TruckerCo’s metallic and mixed compounds are some of the cheapest aftermarket pads you can find, and work just as well as the OEM stuff – plus no fins to rattle. Galfer, Trickstuff, TRP, the options are pretty endless given the ubiquity of Shimano’s pad shape. No matter what brakes you’re running, switching up the pads can make a world of difference, so I’d highly recommend experimenting.
My next hack/bodge/improvement was to swap out the stock IceTech rotors for something thicker and simpler. In this case, it was a set of Magura Storm HC rotors from my time on a pair of MT7 brakes (tied for my top brake choice with these XTRs). Why thicker? My thought was that the less distance the pistons have to retract, the less chance there is for them to get stuck mid-stroke, which can lead to the wandering bite problem. Plus, a thicker rotor is better with heat management and overall durability, so that can’t hurt. Why simpler? IceTech rotors do everything they’re supposed to until they start wearing out, at which point they can get pretty noisy, and become prone to heat warping due to the multi-material sandwich construction. Starting with the 2.0mm thick Magura rotor, I get a whopping whole 0.3mm of wear until I’m at the starting thickness of a Shimano rotor. Marginal gains!
Another aid to keep in mind – and this goes for any disc brake on the market – is keeping your pistons clean. A somewhat fussy job, but easily done by removing your wheel, then your pads, and pushing each piston out with the lever and giving it a good little cleaning with a q tip and some alcohol. There are finer-toothed guides out there, and it really can make a difference, especially in the long run.
Now I know this is a lot of faff for another part people would rather not think about, but I can honestly say these brakes have been performing marvelously for three years of hard riding and relatively minimal maintenance. The only warranty issue I’ve had in that time was the clamp bolt (lever body to bar) snapping, likely because it was overtightened – and Shimano had me covered in only a couple days. If I had my way, they would use a steel bolt for that connection, not the soft aluminum one that comes stock, but surely the 2 gram difference is worth the drop in durability.