Hayes Dominion A4 Brakes | Rider Review

Hayes Dominion A4 mountain bike brakes with a hayes d series rotor review

    Brakes are easily the most important component on our bikes. They keep us alive and out of the hospital, while making track stands and nose pivots that much easier. So why is it that I rarely consider new brake options? For me, I dread the setup process. Once I have a system that works, I stick with it and replace the consumables when needed. In recent years, however, the value that less popular brands are bringing to the industry can’t be ignored.

Hayes Dominion A4 Brakes: The Lowdown

  • $249.99 USD
  • 4 Piston, Hydraulic Brakes
  • Pre-bled for easy install
  • Kevlar reinforced brake lines - Hayes K2 Hose
  • Powerful, consistent bite point

    If you’re like me, SRAM and Shimano have been my default choice considering they are shipped on most stock bike builds. But Hayes, Magura, and TRP were always options that intrigued me considering I would see them on the World Cup circuit or on my favorite YouTuber’s build. So, when my last generation Shimano XT 8020 brakes were getting long in the tooth, I decided to make a wholesale change and give the Hayes Dominion A4 a shot. Unfortunately for me, the task of cutting lines, bleeding, and bedding still remained. These A4’s, however, have some unique features that do make the setup process a bit easier, and aid with maintenance down the road.

    Here’s my 6 month experience with them so far.

Specs, Setup, and Maintenance

    To start, each set of Dominion A4’s include both sintered (metallic) and semi-metallic brake pads in the box. Kits are pre-bled and ready to go, if you’re smart enough to externally route your brakes. While you can use off-brand rotors, it’s recommended to use the Hayes D-Series rotors that were developed specifically for the Domain platform. Rotors are offered in 6-bolt configuration only, and include the appropriate mounting hardware.

    The first thing that impressed me during the install was the hoses themselves. It’s immediately apparent next to my old Shimano hoses that the Hayes “K2” hydraulic lines mean business. Reinforced with Kevlar, they are better protected from outside dangers and wear caused by rubbing inside your frame.

    Once I had the lines cut and calipers loosely mounted with the new rotors, it was time to bleed and then align the calipers for a noise-free ride. When you go to hookup your caliper syringe, you’ll notice two T10 screws on the backside of the caliper. This differs from other brands - the added benefit is that you can thoroughly bleed old fluid out of both sides of the caliper insuring best possible performance. Since these were new and pre-bled, I just hooked up to one of the bleed ports since there is no “used” fluid in there yet.

Hayes Dominion A4 mountain bike brakes with a hayes d series rotor photo from the back of the caliper and from the side

    The second big thing to impress me were the set screws for the mounting posts for fine-tune alignment. We all have our tricks to perfectly lining up the calipers. I usually spin the wheel, grab a fist full of brakes with the calipers loose, then tighten the mounting bolts. That procedure feels prehistoric compared to the Hayes system they call “Crosshair Caliper Alignment.”

The steps are simple:
- Hand tighten the mounting bolts to allow some side-to-side play.
- Push the caliper fully inboard.
- Tighten the mounting bolts a little bit further to keep the position of the caliper.
- Tighten each left and right set screw on the mounting post until you get perfect alignment on each end.
- Torque down the mounting bolts to spec.

    The process and design is simple, but very effective and you will love it. It actually might be my favorite feature of the whole package.

Performance of the Dominion A4 Brakes

    One main driver for me to switch away from Shimano was the inconsistent bite point. Shimano claims this is fixed in the latest 8120 series of XT brakes, but I’ve ridden them and the issue persists (though not as frequently). Right off the bat, the Dominion A4’s are powerful and consistent and the lever feel is amazing. Hayes says that the master cylinder is tuned for the shortest dead-stroke possible, and it does show. As soon as you grab the sculpted lever, you feel pressure in the system.

    Like most modern brakes, the Hayes brake lever features a tool-free reach adjustment for quick trail side adjustments. In terms of ergonomics, they also offer a “SFL” replacement lever or: Small Finger Lever. In case you have smaller hands and find the stock lever a bit too large. Since I’m talking about the levers, it’s worth mentioning that they are not side dependent. This means you can have one spare lever, and swap it to either the front or rear brake if needed for a quick fix.

Hayes Dominion A4 mountain bike brakes k2 kevlar enforced cable and lever mounted on carbon handlebars

    Putting the basics aside, how are they really in use?

    Compared to my old Shimano’s, these are way more powerful and more consistent. Compared to my friend’s SRAM Code RSC, they feel on par with those in terms of power. Above all else, the quality of the hardware and features like the crosshair alignment, dual bleed ports on the calipers and overall ease of use - these start to become a stand out. On big long descents, power or bite doesn’t change. The only effect I’ve seen over time is noise coming from the sintered pads, which is to be expected from a metallic pad. I chose these for maximum power and wet condition performance, should I find myself in those situations.

Final Thoughts

    The Hayes Dominion A4's retail for the same, if not a lower cost, than the big brand top of the line enduro 4-pot systems, which is kind of insane if you ask me, AND they offer more value and better looks. Who wouldn’t want to sport a bronze caliper on their bike? The A4's are now offered in black/grey as well. The packaging, a well thought out design, a full catalog of replacement parts - the list goes on to support their incredible value. I find myself recommending these to everyone that sees them on the trail. It is also pretty cool supporting a legacy brand like Hayes, with roots in Wisconsin, USA.

    My only complaint is that my rear brake lever was scuffed on a recent fall in a rock garden. The bronze finish doesn’t hold up well to being attacked by hard surfaces. But that can be counted as a user error - so I’ll get over it. With great braking power, affordable cost and readily available spare parts, it’s hard to say no or count these out.

I am very happy with my purchase, and I’m sure you will be too.

Hayes Dominion A4 mountain bike brakes with a hayes d series rotor detail photo of the caliper and padsreview

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Nick Hanson



Boulder, CO

Current Bikes: 2019 Yeti SB150, also seeking an additional short travel companion.

Bike Size: Large

Favorite Trails: Hall Ranch, Trestle Bike Park, Free Lunch, Hangover Trail

About Me: Been riding bikes my whole life. But feel I've only been a true Mountain Biker since 2012. Currently trying to take my bike wherever I can ride in conjunction with car road trips. Engaged, and living in Boulder with our 2 dogs.