A downsized version of the excellent Dominion A4 brake, but in this case, less isn't necessarily more.

Product Overview

Overall rating:

Score 7

Hayes Dominion A2


  • Plenty of pad clearance. Bite point adjustment is useful. Light lever action. Spare set of pads included.


  • Not much lighter than the more powerful Dominion A4. We didn't need to use the Crosshair centering feature.


Hayes Dominion A2 disc brake review


Price as reviewed:


Adding to the Hayes range for 2022 is the new Dominion A2, which has an identical lever to the A4 tested here, but mated to a two-piston caliper. According to Hayes this brake is aimed at cross-country and trail riders looking for the best mountain bike disc brake, or folks who want all the adjustment features of the four-piston brake, but with slightly less power and weight.

Hayes Dominion A2 disc brake

The Dominion A2 lever is the same as the A4 with a different finish.

Setting up the Domnion A2 is a no-brainer – the dialled reach adjustment lets you match the lever position to your hand size, and bedding in the brake only took a couple of hard stops. It also features the contact point adjustment to adjust feel and the innovative Crosshair caliper centring, which lets you eliminate any rubbing, something we know XC riders are fastidious about. Again, we didn’t need to use this feature, but to be fair we reckon XC riders are going to prioritise pad clearance over brake feel anyway.

Like the Dominion A4, the main lever pivot features a cartridge bearing, resulting in a light action. It also has the same broad shape, with indents on the face to help grip. It’s short though, so we had to bunch the controls slightly, which is why we’d recommend running a Hayes Peacemaker shifter mount. These cost about £20 and will also save a few grams in weight. For ease of access, the two-piston caliper has top-loading pads and a spare set of metal sintered pads are included in the box (worth £25), which is a nice touch.


When we said the Dominion A2 is lighter, it’s only just - on our office scales the A2 is 9g lighter than the A4. Obviously, you may want to run a smaller disc rotor for XC riding, and that could save another 60g, but this two-piston brake is not as powerful as the A4 and we found we had to pull harder on the lever to get stopped. But there is a way to have your cake and eat it, and that’s running the A4 system with a smaller rotor – lighter, more powerful and only about £20 difference in price.


Weight:brake 294g, rotor 187g
Rotor size:180 and 203mm