Hayes Components Dominion A4 Brake 2019 Mountain Bike Review

Hayes Components Dominion A4 Brake 2019

Reviews / Brakes

Hayes Components 11,599

At A Glance

I’ll be honest, the last time I rode a bike with Hayes brakes was probably back in the early 2000s on the original Hayes HFX9’s (remember those?) and while famous for being incredibly reliable, their braking performance and feel could be best described as, well, wooden. Fast forward the years and Hayes have started from the ground up with the Dominion line of hydraulic disc brakes, with the Dominion A4 here on test aimed at the enduro end of the market. Priced at $229 for each end, they definitely come in at the more premium price point, but do they have premium performance to back that up?

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Key Features

What self-respecting brake for Enduro use would only feature 2 pistons? That’s why Hayes has gone with a 4-pot design to help increase modulation as well as power. Hayes claims that the Dominion’s master cylinder is factory tuned for the shortest dead stroke possible and a crisp bite point. This, in turn, means that incredible stopping power is never more than a slight pull on the sculpted lever blades that work so well for consistent one-finger braking.

The calipers themselves feature dual bleed ports so effectively you bleed either side of the caliper making sure that there is zero air in the system. Very moto. Also built into the calipers is Hayes’ Crosshair Caliper Alignment System, which once used makes you ask quite simply why don’t all brakes feature this? Simply loosely place your caliper on the frame/fork and dial in the crosshair screws so that your disc rotor is sitting perfectly central within the caliper. It really does make it easy to set up straight out of the box.

Moving back to the lever, the sealed cartridge bearings in the levers keep operation smooth and the tool-free bite point adjustment is very simple to get the lever position dialled into personal preferences. The overall look of both the caliper and lever may not be as flashy as some of the offerings from other competitors, but the finish is certainly robust and you know what, I’m quite a fan of the bronze colour!

In Use

Installing the brakes was incredibly straight forward, the Dominions were straight forward enough to bleed and using the Crosshair Caliper Alignment System meant I was able to get the calipers running sweet with no messing about.

Out on the trail and with the pads bedded in (for this long term review I chose to run the sintered pads, although a set of semi-metallic pads are included in the box too) the stopping power was quite literally earth stopping! Before using the Dominion A4 brake, I was running the SRAM Code RSC brakes which aren’t exactly lacking in power, yet with the A4s I found myself able to brake later into corners as the power and modulation available felt a step above the SRAM offerings. They never once felt like they were starting to fade, even on steep, long trails where I was constantly brake dragging and even then, would always stop predictably.

They’ve also suffered their fair share of some hard crashes and apart from a few scuffs on the lever body, they’re holding up fine (which can’t be said of the brakes that these replaced). As for reliability, I’m still running the original pads, I’m yet to bleed them since installation, they’ve been quiet in operation through conditions ranging from hot, dry dusty trails to soaking wet alpine descents. You can’t ask for more than that.


While the brakes themselves may be lacking the overall glossy look and beautifully machined finish of other brands, there is no faulting their power, performance and reliability. For anyone looking at improving their stopping power then the Dominion A4 from Hayes has to be at the top of your list.

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This review was in Issue 61 of IMB.

For more information visit Hayes Components


By Ewen Turner
Ewen Turner is a self-confessed bike geek from Kendal in the Lake District of England. He runs a coaching and guiding business up there and has a plethora of knowledge about bikes with an analytical approach to testing. His passion for bicycles is infectious, and he’s a ripper on the trails who prefers to fit his working life around his time on the bike.

Tried this? What did you think?