Hayes Dominion T4 Hydraulic Disc Brake

Your brakes are arguably one of the most important components on your bike; how they feel and perform can have a huge impact on your riding. The Hayes Dominion A4 has garnered a solid reputation mainly thanks to its power and feel, and with the introduction of the T4, Hayes sought to maintain that performance while dropping some weight. We’ve had a pair out on the trails for about 7 months now, and we’re here to report on how we’ve been getting along.

Hayes Dominion T4 Highlights

• Tooled reach and pad contact adjustment
• “Two Stroke” bleed ports in caliper
• 17mm caliper pistons
• Pad options: T106 Semi-metallic, T100 Sintered metallic
• Low expansion hose with Kevlar weave
• DOT 5.1 fluid
• “KingPin” pad retention
• “Crosshair” caliper alignment system
• 2-piece clamp
• Adjustable banjo connection
• Flip-Flop lever design
• Sealed cartridge bearings in lever
• Weight: 257g (90cm hose & mount hardware)
• Compatible Rotor (not included): D-series (160, 180, 203) w/ QuickBite² and MRC
• MSRP: $324.99 USD per side (excl. rotors and adapters)

Initial Impressions

The Hayes Dominion T4 is very similar in appearance to the A4, with some extra machining and components that help it shed some weight. The T4 features carbon levers (made by sister company Reynolds), titanium hardware, and tooled reach adjustment instead of the tool-free system found on the A4. As per Hayes, the T4 weighs 257g per side compared to 310g for the A4, while the price tag shows $70 USD more per side for the T4.

The brake is finished off with care and exudes an air of quality, despite the low weight making it seem almost gimmicky when you pull it from the box. The lever is smooth to the touch, and the calipers are uniform in finish and color. Only the composite reservoir cover on the lever body seems a little bit out of place with the edges protruding slightly.

Hayes packed a lot into the T4. Both reach and pad contact point are adjustable (albeit you’ll need a small allen key for the job), and the flip-flop design of the lever body means it’s easy to swap sides if need be. The calipers get their fair share of fancy features too: a “Two Stroke” bleed port system (basically one port on either side of the caliper) should make it easier to achieve a good bleed, while the “Crosshair” system helps make micro-adjustments to the caliper’s alignment. Our test sample was delivered with Hayes’ own D-series rotor, a 1.95mm thick rotor designed specifically to provide good bite and reduce unwanted noise (not a typo, Hayes says the rotor is 1.95mm thick, while it states min. thickness 1.7mm on the rotor itself).

On The Trail

Installing the T4s was devoid of any drama. Hayes provided a compact bleed kit which was easy to work with and produced a good bleed on the first try. The dual bleed ports on the caliper are a nice touch if you want to really get after those micro-bubbles that can accumulate on either side of the caliper, without having to flush through the entire system. We also really like the “Crosshair” alignment system, which allows you to be very precise when aligning the calipers with the rotor (and also makes it easier to realign the caliper to exactly the same spot if for some reason you need to remove it from the fork and put it back on again).

Setting up the levers was equally straightforward, although we have a couple of small remarks to make here. First of all, we would have loved to be able to mount both our shifter and dropper remote on the brake levers, but the Hayes “Peacemaker” system is not fully adequate here – it lacks a dedicated option for the dropper side, and it offers a very limited range of adjustment for the shifter. We ended up using discrete clamps for our controls. The 2nd issue we noticed is that the free stroke adjustment does not have a ton of range, we measured it to about 5 mm at the outer end of the lever (compared to a Hope Tech 4 for example, which provides about 10 mm). Nevertheless, we were able to dial in the lever feel to our liking, and head out to the trails.

Within just a few minutes, we felt like we were in tune with the new brakes. The pads bedded in quickly, and we immediately came to appreciate the very light lever feel provided by the T4s. The return spring is not very strong, and the power builds up quickly, which creates a brake that is intuitive to use and that saves a lot of energy on longer rides. It is comparable in lightness to the Hope Tech 4 and a Shimano XT for example, and it offers modulation that is pretty much on par with those two as well.

As testing went on, our bike saw action under a couple of riders, both of which found the brake very easy to get along with. On very long and steep descents we noticed a slight lack of power deep into the stroke compared to our current benchmark brake, the Hope Tech 4. Basically this translates to needing to use a bit more force at the lever when you really need that last bit of power. Make no mistake, the T4 is very powerful and did not suffer from any fading, we’re just nitpicking a bit here to help you understand the differences.

We tested the T4 with both compound options provided by Hayes, starting out with the semi-metallic pads and finishing with the metallic pads. We got along well with both options in fact, and felt like the power delivery was more or less similar across the two compounds. The metallic pads offer a little more direct feel when the pads engage, and they can be a bit noisier when dragging your brakes, but they also offer better pad life and reportedly better performance in the wet (we did not test that aspect extensively at all).

Things That Could Be Improved

As previously mentioned, we found a couple of small issues when testing the T4. We’d like to see a little more range in the free stroke adjustment, and the “Peacemaker” clamp could do with a little work too (to provide a dedicated option for the dropper remote, and more range when adjusting the position of the controls). The T4 is also quite expensive, but you do get exotic materials and a very light brake for the category, so this is not really something that needs to be fixed (you can always opt for the more affordable A4 if you don’t mind the extra grams).

Long Term Durability

We’ve had the T4 running for about 7 months now, on a trail bike that sees a lot of action under two different riders. Pad life has been great so far, and we’ve not noticed any kind of performance degradation over the duration of the test. We’ve not had to bleed the brakes since the first installation, and the reach and free stroke adjustments have stayed in place over the duration of the test as well. A couple of crashes left a few small scuff marks but the finish is robust and the brakes still look fresh.

What’s The Bottom Line?

The brake market has heated up (no pun intended) over the past couple of years, leaving riders with plenty of options to choose from when picking their next stoppers. The Hayes Dominion A4 has held its own ever since its introduction, and this new T4 version offers the same performance in a lighter weight package. The lever requires little force to activate, and it’s easy to feel when the pads are engaging the rotor. There is plenty of modulation on offer as well, creating a very intuitive connection between the rider and the stopping power on hand. Compared to our current benchmark, the Hope Tech 4, the Dominion T4 falls just a bit short in the outright power department, but it’s still a force to be reckoned with and it has cemented its spot among our favorite brakes.

More information at: www.hayesbicycle.com.

About The Reviewer

Johan Hjord - Age: 50 // Years Riding MTB: 18 // Weight: 190-pounds (87-kg) // Height: 6'0" (1.84m)

Johan loves bikes, which strangely doesn’t make him any better at riding them. After many years spent practicing falling off cliffs with his snowboard, he took up mountain biking in 2005. Ever since, he’s mostly been riding bikes with too much suspension travel to cover up his many flaws as a rider. His 200-pound body weight coupled with unique skill for poor line choice and clumsy landings make him an expert on durability - if parts survive Johan, they’re pretty much okay for anybody. Johan rides flat pedals with a riding style that he describes as "none" (when in actuality he rips!). Having found most trail features to be not to his liking, Johan uses much of his spare time building his own. Johan’s other accomplishments include surviving this far and helping keep the Vital Media Machine’s stoke dial firmly on 11.

Photos by Johan Hjord and Tal Rozow