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Tested: Hayes Dominion A2 Brakes

Fit, finish and feel


-$230: Lever and caliper
-$55: Rotor
-$18: Mounting bracket
-Two-piston caliper
-DOT fluid


-Amazing lever feel
-Superb consistency
-Great power


-Short pad retraction can lead to rubbing
-No option for dropper-post lever integration

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Hayes is more-or-less the original player in the hydraulic disc brake world—they were known for their power and comparative reliability. Note the word were. The other brake brands figured out what they were doing, and surpassed the Hayes brand. For a long time. The 4-pistoned A4s put Hayes back on the proverbial map a few years ago, proving they could still produce top-performing stoppers. The Dominion A2 is the two-pistoned evolution of the A4 that adds a dash of light-weight sauce for trail and cross-country crowds. 

I installed the Dominion A2 brakes on my personal bike. They took the place of Shimano’s 4-piston XTs, which I consider to be one of the benchmarks for trail performance. To be quite honest, I was reluctant to test the Hayes on my personal bike. The XTs are very fine brakes, and when riding my personal rig, I want it to be as predictable and mindless as possible. But at the time, I had some DOT fluid bleed kits that I really needed to test, and didn’t have another bike to install them on, so on they went.

Setting up the Dominions was pretty much a cakewalk. Both front and rear installed with a minimal bleed, which was surprising considering the battle I waged with my internal cable routing. Plus, the two-piston A2 doesn’t feature the dual caliper bleed ports that the A4 does. Hayes’ Crosshair alignment system makes the next step just as easy. It’s basically a grub screw that goes through the caliper at each of the mounting bolts which, when the caliper has been gently tightened down, can be turned to slowly move the caliper to align it to your rotors before tightening the caliper the rest of the way.

The lever shape of the Dominion A2 is far closer to Shimano than SRAM, with regards to the positions of its pivot and its bends. Like the Shimanos, the Hayes have a textured metal lever with a solid curve at the end for a secure, non-slip feeling. The main difference is that the Hayes has a rounder blade profile that I found a tad more ergonomic than the Shimanos. 

While lever shape is largely personal preference, lever feel is a touch more universal. And this is really what makes the Dominion A2 special. There’s very little dead stroke before pads hit rotor, and the levers pivot smoothly around sealed bearings. The contact point is firm and well defined with just enough give to provide accurate modulation feedback. This lever feel matches the performance of the brakes: The contact bite is solid but not harsh, and modulation is precise and predictable. Power-wise, the A2s hold their own. I was expecting a dip in max grab-for-the-squeeze going from four to two pistons, but this wasn’t the case. In fact, I have a Dominion A4 front brake that I was ready to install to boost power, but I haven’t found the need. If I were riding more park, downhill, or sustained enduro-style trails I’d likely opt for the A4s, but on my 140-millimeter trail bike the two pots provide plenty of power. And with that great power also comes great consistency. Whether I was rapidly on and off the brakes, or dragging them down long descents every lever pull felt the same. No floating bite points or weird ramping/spongy lever positions. 

As far as on-the-fly adjustability goes, the A2s offer an indexed metal knob sleekly integrated in the lever blade near the pivot point. I appreciated its low profile, as it’s one less thing to snap off or get snagged if the bike goes tumbling, or if I clip a tree. Furthermore, braking performance felt consistent throughout the reach adjustment; even when dialed in quite close to the bars. And if you still can’t get it close enough, Hayes offers a youth-friendly lever blade whose neutral position is more small-hand friendly.

Stop! Hey, what’s that sound? I’m happy to say the Dominions are much more Simon and Garfunkel than they are Buffalo Springfield—that is to say, even after a fair bit of contamination, rain, mud, and winter road salt (regrettably), when the levers are pulled, it’s usually “the sound of silence.” For clarity, any brakes will howl when contaminated, but these seem slower to squeal, and quicker to quiet back down than any other brakes I’ve run. Hayes claims that its rotor design has a lot to do with the quiet nature. I ended up having to run a Shimano rotor for a ride or two after I had a tire failure on one of my wheels, and didn’t notice much difference, noise or power-wise, but realized that the Hayes rotors are noticeably thicker than the Shimanos (and SRAMs). This extra girth makes for a longer-lasting, more durable, less vibration prone rotor, but also means A2s are not as compatible with non-Hayes, or other after-market rotors.

On the tune of the rotors, these aren’t quite as ‘finished’ as other high-end rotors; all of the edges are razor-sharp, even around the centers and rotor bolts. This sharpness took a small slice of skin off my knuckle when my torx slipped off the rotor bolt during initial installation. Both SRAM and Shimano’s rotors are definitely duller, and also offer aluminum-centered two-piece options.

Sticking with nit-picks, the A2’s pad retraction is shorter than SRAM’s or the Servo-Wave-equipped XTs. At rest, the pads sit a little closer to the rotor, partly as a consequence of that minimal dead stroke. I felt like this caused extra rubbing in wet or gritty conditions—really, a pretty minor complaint in the grand scheme of things. 

Reliability has been outstanding, too. The A2s have hung on my bike for nearly a year now, I haven’t had to do a lick of maintenance on them since bolting them on. No bleeds, no rotor warp, no realigning calipers, nothing. 

I installed the A2s thinking that I’d be back on my trusty old brakes after a couple months, but I now have no plans to swap them back. The overall feel, control, consistency, reliability, and power that these stoppers supply, to me, noses out the other offerings out there at this weight and price point.

Photos: Anthony Smith