Hayes Dominion A4 Long Term Review

Hayes Dominion Brake on Fox 38

Hayes may have been in the mountain bike brake business since 1997 but they’ve flown relatively under the radar here in the UK in recent years. The loyal following they amassed on the other side of the Atlantic never quite made it over the water, we’ve always been more enamoured with either of the big S’s, or the homegrown options from Hope in Barnoldswick, but the tide is slowly turning and word is starting to spread about the (not so) new kids on the block.

It’s 2018 and the newly released Dominion A4 brake has just won Pinkbike’s “Component of the Year”. Starting from a blank sheet, Hayes’ engineers were tasked with a total redesign of their brake offering to address everything a modern mountain biker could want; a smooth and short lever throw, total reliability, easy setup and huge power. These are big goals to hit in a crowded modern brake market, so to find out if they scored, our Guide and Coach Tom has been riding the Dominions on his enduro bike for the past nine months.

Hayes Dominion A4 brake on Toms Nukeproof Mega

 Initial setup and bleeding

The Dominions run on DOT 4 or 5.1 fluid and use a simple threaded bleed port at both the lever and caliper. Interestingly the caliper features two bleed ports, something usually only seen on motorsports brakes. A bleed port on either side of the pad slot lets you flush fluid around the whole caliper ensuring no air remains. On the first bleed I started by fully flushing the caliper before bleeding the whole brake, fluid moved through the system smoothly without much resistance and I was able to get a great result immediately. Most brakes seem to have little tips or tricks to get the best bleed possible, going in armed with no prior knowledge and getting a perfect result first time is testament to how easy to bleed these brakes are; simple fittings, no convoluted techniques, just two syringes and 10 minutes. 

On every set of brakes I set up I always take the time to properly lube and cycle the pistons to remove as much friction as possible and get all four pistons biting at the same time. These brakes were no different, however they definitely have the smoothest pistons out of the box that I’ve come across on any brake set. This might seem like a fairly trivial point but any friction in the piston seal will translate to a lever that’s harder to pull; a lighter lever puts less stress on your forearms and reduces hand fatigue and arm pump on long descents.

Hayes Dominion A4 Lever on Burgtec bar

Fitting the pads is simple enough, they fit from the bottom of the caliper, snap satisfyingly into place and the beefy pad pin, supposedly adding to the stiffness of the caliper, always threads through easily. Centering the brake is where one of the most unique aspects of the Dominions comes in, a feature Hayes call Crosshair Alignment. To achieve the shortest lever throw possible, the Dominions run their pads quite close to the rotor which could potentially make getting a rub free setup more challenging. To help with the process, Hayes have tapped some small holes on the outboard side of the caliper mounts and installed a grub screw in each one. The idea is that you wind these grub screws out a few turns, line up the caliper so the non-drive side pad is just grazing the rotor and slightly tighten the mount bolts, then slowly rotate each grub screw to move the caliper with control until it’s centred and rub free. In use this system works almost entirely as advertised. With brand new brake pads and rotors the gap between them is so small it’s basically invisible, and while I wasn’t able to achieve absolutely no rubbing at all the Crosshair system definitely allowed me to fine tune the position of the caliper with significantly more control than just moving it by eye. Any amount of rubbing I was left with was very minor and faded away quite quickly as the pads wore.

As a setup experience goes everything was straightforward and easy enough that I didn’t need to repeat any steps to get a feeling I was happy with. Having never worked on these brakes before I was ready to spend a bit of time getting everything right, but as it turned out I needn’t have worried. 


Having used SRAM Codes for a number of years, it was quite refreshing to have to start from scratch with brake setup again. I like a brake with the lever reach set fairly close to the bar with a small amount of free throw in the lever travel. Codes sometimes need a few tweaks to feel just how I like but with the Dominions I just set the reach and off I went. The free stroke in the lever is very short with a standard bleed and piston setup with no need to overbleed or advance the pistons. For those who like a longer lever throw there is a tooled adjuster on the brake lever, it’s set to the minimum amount of throw from the box and that’s where I’ve left mine. 

Tom riding the Dominion on the Golfie at Innerleithen

To get the most power out of my brakes I always spend the time to really bed the pads in on tarmac before hitting the trails. Getting the pad material evenly spread on the rotor gives better initial bite and outright power so it’s a no brainer for me. Hayes D-series rotors are 1.95mm thick and deal with heat very well, this meant the bed in process took a little longer than I anticipated, but the results were more than worth it.

A reach adjuster built into the lever blade means you’d really struggle to damage it in a crash, unlike other adjusters that poke out and can get snapped off. My Dominions have had an up close and personal taste of Scottish soil a few times and each time have come away totally unscathed; a sturdy design across the lever body and blade makes me think this is more than just luck. The lever blades run on cartridge bearings making them solid in the lever body itself and adding to the overall smooth feeling of the lever. Combined with the low friction pistons, small pad gap and thick rotors, the lever feel of the Hayes is as advertised; very light with a short throw and solid bite point.

Hayes Dominion Brake Lever on Toms Mega

Overall power from the Dominions is huge, these must be the most powerful brakes I’ve used, and that power doesn’t diminish with heat. Long descents where you’re hard on the brakes for extended periods don’t result in any change at the bar; the lever feel and bite point remain the same. Initially the light lever meant I was overpulling the brakes, out braking myself into turns. After a few rides my fingers had reconfigured themselves, now I find other brakes noticeably harder to pull at the bar. This easy lever pull also means the power is very easy to dole out, with such a small amount of mechanical friction in the system, any tiny change at the bar is translated to the pads, letting you find the sweet spot of braking power and modulate it as you need to. 

In my time with the Dominions I’ve not had to do any unplanned maintenance, and the level of planned maintenance I’ve had to carry out has been much lower than I had expected. To begin with, pad life on these brakes is fantastic, it’s been nine months and I’m still on the original set of front pads which I can’t say of any other brake I’ve used. Not only that but the power and bite is still just as good as the day they went in. Both brakes will get a bleed fairly soon just as a matter of course when I do eventually replace the front pads, but again the lever feel is still rock solid. Writing about the reliability of these brakes is tough, nothing has come loose, everything is as solid as the day they were new and I don’t anticipate that changing anytime soon, simply put they’ve been as close to a fit and forget part as you can get whilst at the same time blowing me away with their performance. 

Tom riding Wardell Way with the Hayes Dominion A4

For someone willing to step away from the more obvious choices, the Hayes Dominions offer incredible performance and steadfast reliability, and if you’re a rider struggling with arm pump or hand fatigue these might offer some degree of respite from your symptoms. Savagely powerful, infinitely controllable and totally dependable, these Dominions have jumped straight to the top of my list for brakes. 

Interested in trying something different? We’ve Dominion A4 brakes in stock in the limited edition purple right now, and demo bikes equipped with them to let you feel them in action for yourself.

☎️ 01896 831429

📧 shop@tweedvalleybikes.co.uk

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