Avid X0 Trail Hydraulic Disc Brakes

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With SRAM releasing a full line of “Trail” specific brakes it’s about time for some feedback on the X0 Trail brakes that were released last year. The X0 Trail brake is aimed at the Enduro, all-mountain market and utilizes a 4-piston dual-diameter caliper. What’s unique about their design is the piston sizing, with the leading pistons being smaller than the trailing pistons.  This allows the smaller piston to engage the pad first creating a “toed” engagement, resulting in more modulation at the lever. Another update over the X0 Elixirs is a redesigned TaperBore master cylinder.

I installed these brakes with 160mm HSX rotors on my Giant Trance X.  At 25 lbs, a slack head angle, and low bb, this bike was a perfect candidate for the install and test. I’ve had about 2 months on these so far with trail type and conditions varying quite a bit.  Long XC rides, steep descents, and a little bit of jumping gave these brakes a run for their money.

First off, let’s get the “bad” bleed and noisy rotor gripes of the past out the way since I feel that have been resolved.  With these brakes the bleed port on the master cylinder has been relocated to the low pressure side.  What this results in, is less chance of air sneaking its way into the master cylinder.  With the old style, the bleed port was a part of the pad contact adjustment, on the high pressure side, and this would result in difficult bleeding for some and the chance for air to sneak into the system with use due to the complexity of the adjustment.  With these improvements the brakes didn’t require an initial bleed and haven’t required one yet.  Something I wasn’t able to say about the Elixir CRs I settled with using on this bike previously because they weren’t consistent enough when set up on my downhill race bike. I can say the bleed location change was definitely the improvement because getting rid of the pad contact adjustment by using Code Rs on my DH bike fixed the consistency issue.

Avid did look into the rotor noise and you’ll find that the new HSX rotor no or little noise with appropriate set up 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 at extreme loads.  Braking causes friction, and friction generally causes vibrations and finally vibrations are noise.  I want my brakes to cause friction so I’m ok with a bit of noise under heavy braking.  It means they’re working.

Now onto what has impressed me quite a bit with these brakes.  This wasn’t my first 4-piston brake so I had quite high power expectations and was very impressed with the amount of power on steep descents with 160mm rotors though.  The biggest thing 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 for the beginning of the season I would expect a bit of pump but this never happened.  I’m pinpointing this on the lever feel and power you get.  When pulling these brakes in you never get that “wall” feel.  Some may say this is a “spongy” feel.  I’ve overlooked this parking lot feel and focus on how the lever feels on the trail.  On the trail I never once noticed any sponge or felt I was using strength to grab a bit more brake.  What surprises me is the lever feel under last minute braking.  This is when you expect to use a ton of effort pulling that lever in to get that power to make the turn.  I’m constantly surprised entering corners with relaxed hands but skidding/drifting my tires into the perfect line.  This performance can be pinpointed to their 4-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 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.  This mild “sponge” feel was gone on the trail and not once noticed.  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 light package.