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Reviewed: Avid X0 Trail Brakeset

With SRAM’s release of a full lineup of trail-specific brakes, it’s about time for some feedback on the X0 Trail brakes that were released a year ago. The X0 Trail brakeset is aimed at the enduro, all-mountain market, and utilizes a four-piston, dual-diameter caliper. Four-piston calipers are nothing new to mountain bikes but what’s different about this design is the dual diameter pistons. In the initial lever stroke, the smaller leading piston starts pushing the forward portion of the pad, creating a “toed” engagement. This results in more modulation at the lever during this portion of the stroke and the control is precise and effortless. Another update over previous iterations is a redesigned TaperBore master cylinder addressing any bleed issues.

I installed these brakes, with 160mm HSX rotors, on my Giant Trance X. At 25lbs, and with a slack head angle and low bottom bracket, this bike was a perfect candidate for the install and test. At this point I’ve been on these brakes for seven months, with trail type and conditions varying quite a bit. Long XC rides, steep descents, a few of those new enduro races and a bit of jumping gave these brakes a run for their money.

First off, let’s get the “bad” bleed and noisy rotor gripes out the way, given that I feel that they’ve finally been resolved. On previous generations, the bleed port was on the high-pressure side of the hydraulic system, which resulted in tedious bleeding and the chance for air to sneak into the system. With these brakes, the bleed port on the master cylinder has been relocated to the low-pressure side of the system and the chances of air sneaking into the system have been eliminated. With these improvements, the brakes didn’t require an initial bleed, and they haven’t required one yet—which is something I wasn’t able to say about the Elixir CRs.

Avid also looked into the rotor noise, and you’ll find that the new HSX rotor creates little or no noise with a proper setup and “normal” use. I did find that under some extremely heavy braking, you could hear the infamous turkey gobble trying to break out. However, I can’t view this as a fault, as it only occurs under extreme loads. Braking causes friction, and friction generally causes vibrations, and finally, vibrations are in fact noise. I want my brakes to cause friction, so I’m ok with a bit of noise under heavy braking. After all, it just means that they’re working.

Now, onto what’s impressed me quite a bit about these brakes. These weren’t my first four-piston brakes, so I had quite high expectations for power, and I was very pleasantly impressed with the braking power on steep descents with 160mm rotors. The biggest thing that I noticed is something I’m going to call an efficient lever feel. Not once have I noticed any signs of arm pump. Generally, on longer descents at the beginning of the season, I expect a bit of pump, only this never happened. I’m pinpointing this on the lever feel and power that you get. When pulling these brakes in, you never get that bottomed out feel. Some may consider this is a “spongy” feel  while riding around the parking lot but that’s never the impression I had on the trail.

On the trail, I’ve never once noticed any sponge or felt that I was trying to get more out of the brakes. What surprises me is the lever feel under heavy, late braking. I’m now entering corners and technical sections composed with relaxed hands, and effortlessly hitting my braking points. This performance can be pinpointed to their four-piston caliper with dual-diameter pistons. Once the larger, trailing piston, engages towards the end of the lever stroke, power is greatly increased without any change in lever feel (something you don’t get with the cammed, Servowave lever). What I like to call this is an “efficient” lever feel. With relaxed hands, I’m able to ride looser, smoother, longer, and happier.

Overall, I would say the X0 Trail brakes are a huge improvement over the previous generation of Avid brakes. Improved bleed, power, and lever feel are all noticeable, and the only thing I felt was a bit off is lever feel during the parking lot test but this mild “sponge” was never felt on the trail. The power was always there when I needed it, and I never felt like I was death gripping my lever for more power. This brake is perfect for the all-mountain, trail, and evolving enduro crowd, with its massive power, efficient lever feel, and durability—all in a nice lightweight package.

Photo Credit: Ian Matteson