Today’s trail bike riders all but demand 4-piston brakes on their mountain bikes. While one could argue whether everyone needs the added stopping power of all those pistons, like a lot of riders I’ve been spoiled by 4-piston brakes these last few years. The new Hayes Dominion T4 brakes bring all the power in a lightweight, easy-to-use package that certainly deserves a place on high-end trail and all-mountain bikes.
Hayes Dominion T4 specs
The Hayes Dominion T4 brakes take design cues from the popular Dominion A4 brake set while dropping weight wherever possible. The T4s feature carbon levers, titanium hardware, and tooled reach adjustment. Eliminating the tool-free reach adjustment wheel alone likely saves considerable weight and a bit complexity, not to mention the fact that most won’t make adjustments beyond initial setup. Officially the Hayes Dominion T4 brakes weigh 257g per brake compared to 310g for the Dominion A4s.
There’s also tooled pad contact adjustment available at the lever. I tested the brakes with T106 semi-metallic pads, and Hayes also offers compatible sintered T100 pads.
This system is designed to use DOT 5.1 or 4 hydraulic fluid, according to the label on the main reservoir. The Hayes Dominion T4 brakes are a premium set featuring a low expansion, Kevlar-reinforced hose and a stout Kingpin retention bolt. There’s no safety clip opposite the bolt head; just a bit of blue thread locker seems to do the trick. Personally I never understood how that tiny, easy-to-lose clip did anything anyway.
Bleeding brakes is a hassle, and anything that promises to make the process quicker and less error-prone is welcome. The Hayes Dominion T4s feature a “2-stroke, dual port” bleed system which makes it possible to bleed the brake at the caliper to remove pesky air bubbles without performing a full bleed from the lever.
Hayes is calling the Dominion T4 brakes “limited edition” due to the fact that the product is produced in small batches which in turn affects availability. In particular the carbon levers are produced by carbon wheel manufacturer and sister brand Reynolds, which limits the opportunities for lever production.
Hayes Dominion brakes feature a system the call Crosshair that helps make caliper alignment more accurate. I installed the T4s as usual, setting the bolts loosely, spinning the wheel, and squeezing the brake firmly to lock the wheel in place. I tightened the bolts and had perfect alignment on the first try with both wheels and didn’t need to touch the Crosshair screws. That being said, it’s not unusual to need to make micro adjustments to get calipers aligned and rub-free and the Crosshair system is a nice feature.
The Dominion T4 brake levers attach to the bars with a two-piece clamp which is nice for making brake swaps without needing to remove grips and remotes. The downside is these aren’t compatible with Shimano I-Spec shifters out of the box which for me meant hunting down an adapter for my shifter before installing the brakes.
In a similar vein, Hayes only offers 6-bolt versions of their D-series rotors. I needed a Centerlock adapter to fit the 180mm D-series rotors to my Reynold wheels front and rear. Upgrading from SRAM brakes promises a smoother path, at least in terms of needing adapters.
Once everything was installed on the bike I followed the Hayes instructions for bedding in disc brakes and hit the trail.
On the trail with the Hayes Dominion T4 brakes
I’ve been running the Hayes Dominion T4 brakes on my hardtail this fall and winter. Yes, some say it’s the most wonderful time of the year but in my experience, it’s also the noisiest time of year for brakes subjected to wet and cold conditions. Despite riding through some wet and gritty conditions, the T4s in conjunction with D-series rotors have been quieter than any set I’ve tested. Hayes says the rotors use Modal Resonance Cancelation to quiet noise and vibration based on the shapes cut into the rotor, and in my experience, it works as advertised.
Hayes does a good job minimizing dead stroke in the Dominion T4 brakes. The calipers feel like they begin engaging almost immediately, and progressively build toward the bite point. On flow trails, feathering the brakes to manage speed into corners feels intuitive and consistent from ride to ride, regardless of lever reach.
In more aggressive braking situations the Hayes Dominion T4s deliver their power emphatically. The bite point is crisp for quick, controlled stops and comes toward the middle of the lever, leaving plenty of room for additional power when necessary.
Slowly easing off the brakes on steep descents yields smooth performance, making it easy to avoid stutter stop and go riding. The lever feels solid with very little flex which is reassuring when traversing extreme slopes.
On longer rides I noticed the lever clamp bolts protrude a bit and feel sharp, leading to discomfort when reaching for the shifter and dropper remote, even when wearing thicker winter gloves.
The Hayes Dominion T4 brakes replaced a pair of Shimano XT M8120 brakes I had been running for more than a year at about the same time I also started testing a bike with SRAM Code RSC brakes. Despite not playing as nicely with Shimano standards, the Dominions look and feel much more similarly to the Shimanos than the SRAMs.
With premium hardware and a well thought out design, the Hayes Dominion T4 brakes deliver more than enough progressive power for trail and all-mountain riding in a lightweight package.
- Price: $325 per brake
- Buy from Worldwide Cyclery.
- Powerful, 4-piston design
- Adjustable reach and pad contact
- Lightweight and easy to maintain
Pros and cons of the Hayes Dominion T4 brakes.
- Doesn’t work with Shimano wheels, cockpit out of the box
- Bar clamp hardware is sharp to the touch
Editor’s note: Updated to add a paragraph about the nature of the “limited edition” label.
You lost me at DOT 🤣