Hayes Do­min­ion A4 brakes

£249.98 (per end)

Mountain Biking UK - - WRECKED & RATED -

Hav­ing dom­i­nated the disc brake mar­ket in the late 2000s with the HFX, Hayes have been in the wilder­ness for a while. They’ve spent sev­eral years data-log­ging brak­ing habits and then de­vel­op­ing the Do­min­ion A4, and it’s paid off. This is a brake that per­forms well in real-world con­di­tions, while be­ing as user-friendly as pos­si­ble.

The ‘clean sheet’ ap­proach in­cludes thicker-than-av­er­age ro­tors (1.95mm) and grub screws for mi­cro-ad­just­ing the po­si­tion of the long four-pis­ton cal­liper to en­sure rub-free align­ment. Each brake is fac­tory-tuned for min­i­mum ‘dead stroke’, so the pad en­gage­ment is no­tice­ably prompt and con­sis­tent. Reach is ad­justable via a dial set into the lever blade and you can ad­just the bite point with a 2mm Allen key

Even with four big 17mm pis­tons, Hayes’ ‘LoFi’ (low lever force, high pis­ton force) de­sign and the fact that semimetal­lic, rather than sin­tered, pads are fit­ted as stan­dard mean that the brak­ing is gen­tly pro­gres­sive, not grabby. The bear­ing-mounted lever blades, solid han­dle­bar con­nec­tion and care­ful­ly­de­signed seals through­out mean that com­mu­ni­ca­tion is very clean too, no mat­ter how hard you’re pulling or how sub­tly you’re re­leas­ing the lever. That makes the brake safe and sen­si­tive to use in slip­pery con­di­tions, which is great news now that we’re head­ing into the sea­son of treach­er­ous trails.

You can up the punch and bite with sin­tered pads, but as it stands you’ll def­i­nitely want to use 203mm ro­tors to boost power for grav­ity or e-bike use. At 489g (314g for the brake hose and cal­liper, 159g for a 180mm ro­tor and bolts, 16g for the mount­ing bracket) it’s heav­ier than SRAM’s Code RSC (487g), Magura’s MT7 (439g) and Shi­mano’s Saint (474g), which all feel more pow­er­ful on the trail. With big­ger ro­tors, it’ll end up slightly heav­ier again. It’s the same weight as the less pokey Shi­mano XT four-pis­ton unit though, and 40g lighter than TRP’s mon­ster G-Spec Quadiem.

Hayes have in­cluded some neat de­tails for ev­ery­day use. Rather than just hav­ing a sin­gle bleed port at ei­ther

end for flush­ing bub­bles out of the DOT 5.1 sys­tem, there are two built into the cal­liper (one for flush­ing out each side of the block). This de­sign worked re­ally well when we needed to re-bleed the brake af­ter in­stal­la­tion. Also, the pad shape and the cut-outs in the ‘D-Se­ries’ ro­tor have been de­signed to can­cel out likely vi­bra­tion fre­quen­cies and cre­ate a noise­can­celling ef­fect, and they’ve cer­tainly been quiet so far. We can’t com­ment on wet-weather pad wear yet, but they’ve han­dled the heat of long des­cents fine. Hav­ing to re­move the wheel to drop the pads out the bot­tom of the cal­liper is ir­ri­tat­ing though, and while the brake is cer­tainly fea­ture rich, that’s re­flected in the high price. Guy www.hot­lines-uk.com

A com­mu­nica­tive and user-friendly, if not par­tic­u­larly pow­er­ful, brake that puts Hayes back in the game

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