Avid’s new X0 Trail four-piston caliper delivers heaps of power – supposedly more than Shimano’s XTR Trail – while still retaining a tidy caliper size and shape (James Huang/BikeRadar)

Avid’s new four-piston X0 Trail hydraulic disc brake
fills the gap in between the standard two-piston X0 and the more gravity
oriented Code range. It’s impressively powerful but still reasonably light,
plus it’s refreshingly quiet for what now seems to be the best option in the
company’s range for a do-all aggressive trail and enduro brake.

That extra power –
more than the standard X0 but less than Code and claimed better than Shimano’s
XTR Trail
– comes courtesy of a new two-piece aluminum caliper that
weighs just 7g more than the standard X0 two-piston body while still retaining
a trim and tidy appearance. Four pistons allow for longer pads with more
surface area like on Code but newly differential piston diameters generate
greater clamp force on the front of the pads than the rear – the disc brake
equivalent of toe-in on rim brakes.

The master
cylinder features Avid’s second-generation Taperbore internal
architecture for easier bleeding and improved long-term performance than
earlier models but the big story here is the new lever blade pivot. Rather than
go for all-out weight savings, Avid have instead taken another page from Code
and incorporated a cartridge bearing pivot that’s slop-free and more
positive-feeling in your hands.

Additional features include carbon fiber lever blades, titanium hardware, tool-free reach and pad contact adjustments, rotating banjos on the caliper bodies, a new 170mm-diameter rotor option, and slick-looking black or silver high-polish finishes.

Differential piston diameters – 16mm and 14mm – yield more clamping force on the forward-facing edge of the pads than the rearward-facing edge

Interesting, Avid
have done away with their long-running CPS caliper washer system on the X0 Trail in
order to save a bit of weight. The company say frame and fork alignment has
finally gotten consistent enough that they’re no longer needed – although we at
BikeRadar still find them useful on
occasion so we’re sorry to see them go. One other note: X0
Trail uses its own pads that aren’t compatible with either standard X0 or Code.

Claimed weight for
a complete Avid X0 Trail brake is 340g per wheel (front, 160mm rotor, post
mount). Suggested retail price is US$310/£233/€276 (including VAT), with
expected availability in shops from June.

Avid have made a
few tweaks to the standard X0 as well, including an updated forged aluminum
two-piece, two-piston caliper and a slightly revised lever body. Claimed weight
drops to 315g per wheel though much of that comes from again omitting the CPS
washers on the calipers, along with the pad contact adjustment on the lever. Suggested retail
cost for the standard X0 is $261/£196/€232, including VAT.

The standard Avid X0 brake remains in the line-up for riders who’d prefer to save a few grams and don’t need the additional power of the X0 Trail

Shredding on the new X0 Trail

We sampled the new
Avid X0 Trail over two days in Santa Cruz, California, near and around the
grin-inducing trails of the UCSC campus, and were thankful that the new brakes
performed as well as they did. While these trails never cease to entertain, the
downhills are extremely unforgiving if your brakes aren’t up to snuff.

Power is notably greater than that of the standard X0. It comes on strong but without
being overly grabby and modulation is excellent, especially at the limits of
tire adhesion. On one occasion, we foolishly attempted to follow former and
current pro riders Tyler Morland and Curtis Keene down an especially fast and
twisty downhill and not surprisingly, got in well beyond our
comfort zone. Thankfully, we were able to scrub off speed quickly
and confidently despite the bumps, jumps and loose ground along the way.

That being said,
it was still easy to lock up the rear wheel at will for swinging around tight
corners but it was invariably only by choice, not by
accident. Perhaps the most
pleasant surprise was that the X0 Trail isn’t just powerful, it’s also very quiet – at least with the stock organic pads fitted and on the stout mounting tabs of
our Giant Reign and Yeti SB-66 test rigs. 

Cartridge bearing pivots make for a much more solid feel in your fingers than current bushing-equipped Avid levers

Even under very hard braking, the
system emits barely a whisper and as with previous Avid brakes, the generous
pad retraction makes it easy to set things up rub-free. You do need to
ensure the caliper is very well aligned, however, to ensure that noise-free performance.
We found that even a slight variance from square will yield some audible
objection but even then it’s much less irritating in both volume and tenor than
earlier models. Hear, hear – or not, in this case.

We were honestly
surprised at the improvement in lever feel with the cartridge bearing pivots.
The standard X0′s large-diameter aluminum sleeve and plastic bushing never
seemed overly objectionable but the X0 Trail does feel more precise, with a more
fluid, lower-friction feel and better feedback, particularly when combined with
Avid’s consistently satisfying lever geometry. The pad engagement point is
obvious and positive, too – though perhaps not quite as distinct as on
Shimano’s Servo Wave-equipped models.

initial impressions were outstanding and we walked away with not a single
key item on our brake performance ‘want’ list left unchecked. All Avid have to
do at this point is maintain the long-term reliability and the X0 Trail will be
far and away the best all-purpose mountain bike brake in the company catalog.

You can follow BikeRadar on Twitter at and on Facebook at