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Hayes HFX9 Carbon and Avid Juicy 7
By James Sharp
When you think of disc brakes, two names generally spring to mind, Hayes and Avid, but for very different reasons. Hayes has been in the disc brake business longer than just about anyone. Their brakes can be found on cross-country bikes, downhill bikes, Harley-Davidson motorcycles, heavy equipment, snowmobiles... you name it, Hayes probably makes a brake for it. Avid, on the other hand, made there name in disc brakes by producing the first mechanical disc brake
that was worthy of being compared to hydraulic discs, and in many cases surpassing them in power and reliability. Here reviewed is Avid’s much-anticipated Juicy 7 hydraulic disc brake--a sequel to their mechanical brake--along side Hayes’ HFX9 Carbon brakes. Both of these brakes are designed for cross-country riding/racing and come with 160mm rotors, although both have the option of bigger rotors. Hayes makes adaptors for 205mm rotors and the Juicy is available with 185mm and 205mm as well.
Hayes HFX9 Carbon
Avid Juicy7
Hayes HFX9 Carbon
 For 2004 Hayes has two separate lines of hydraulic disc brakes: the lower end HFX9 and the more expensive HFX Mag. Both lines use aluminum G2 calipers and use the same rotors and pads. The difference is in the levers. The HFX Mag uses a magnesium lever body and has a split clamp to ease installation without requiring the removal of grips or shifters. The HFX9 uses an aluminum lever body without the split clamp. Both levers are “flip-flop”, meaning that they can be run left/front or right/front without disconnecting the brake line.
Our HFX9s are the $179 Carbon version, meaning that the lever itself is made of carbon fiber. Ours also came with Hayes’ optional Mud Cutter Wavy rotor. The brakes came bled and ready to roll. Installation was easy and we were able to set up the brakes to be drag free out of the gate. Hayes uses the post mounts found on Manitou forks, but can be mounted to International Standard (IS) mounts using an available adaptor. This design allows for the caliper to adjust side-to-side without resorting to shims. The brakes have semi-metallic pads, which shortened the bedding-in period. By the end of the first ride, these brakes were almost to full power. Other benefits to the semi-metallic pads include reduced brake squeal, better modulation, cooler system temperature and reduced cost. The available sintered metallic pads yield longer life and more power but at the expense of modulation and noise. During our time using the HFX9s we never had a problem with power. The pad life seemed on par with other disc brakes out there. The only time we got them to make any noise at all was at the end of long, steep downhills when the brakes were smoking hot. We managed to discolor both the front and rear rotors. Even at higher temperatures, the Mud Cutter rotor stayed true and never let out a shudder or felt weird at the lever.
The lever was the one area where our testers couldn’t agree. The carbon lever is fatter than its aluminum counterpart, some of us loved it, some hated it. There didn’t seem to be any middle ground. In addition to the width of the lever, it lacked a meaningful hook at the end, some thing I find almost necessary for one-finger braking. The reach adjust had a very usable range and finding the correct reach was easy from the biggest hand to the smallest. The lever shape worked well for both twist and trigger shifters.
Really the only problem we had, other than the possible lever shape issue, was heat dissipation. Often mountain bikers talk only of power, i.e. if a brake has enough power for racing, or aggressive cross-country riding. These had plenty of power. The problem was during any long or steep downhill, the brakes would be fine for while, but then the heat would overcome them and they would begin to fade. In order to get full power back we would have to stop and wait for the brake to cool a bit. A larger rotor would go a long way in curing this problem, but Hayes only makes 160mm or 205mm rotors. Many cross-country forks, Fox being one brand of them, aren’t strong enough to handle the big rotor and the use of any rotor larger than 185mm will void the forks warranty. It would be nice if Hayes would make a 180mm or 185mm rotor available, this would increase the usability of the HFX9 without giving up too much in the way of modulation or weight. Besides, I have never met anyone who wouldn’t want just a little more power.
Avid Juicy 7
 Avid’s $184 Juicy 7 is a brand-new-for-2004 brake. Avid had their work cut out for them if they were to produce a hydraulic brake as reliable and strong as their mechanical brake. Rather than having to design a brake to work with existing levers, Avid needed to design a complete system. What they succeeded in doing is building the most adjustable hydraulic disc brake on the market. Starting with the lever, Avid moved the lever pivot closer the handlebar. This allows the lever to be more parallel to the bar when you are pulling the hardest. The benefit is more efficient use of your hand strength and an increase in modulation. Next they added the Speed Dial pad contact point. This dial allows you to adjust dead lever throw. It doesn’t affect the pad or lever travel, rather how far you pull the lever before the pads begin to move. This allows the user to customize the brake to fit him, rather than having to put up with the lever feel the manufacturer wanted you to have. It also allows the user to balance the right and left levers for a more uniform lever travel. Rounding out the lever body is the location of the reservoir. Avid tucked it behind the body to keep it out of harms way, and allow the lever to be flipped over to run the front brake on the right without having to swap brake lines. The lever itself is a joy to use, typical of Avid levers. It is shaped right with a pronounced hook at the end, perfect to keep your finger from slipping off. The reach adjustment is indexed; each click equals 1mm of travel at the end of the lever. The lever has a split clamp, easing installation without requiring grip removal.
 Avid didn’t stop at the lever, either. The caliper gets the same Tri-Align Caliper Positioning System (CPS) that their mechanical brake has. This system compensates for miss aligned brake tabs by using conical washers to allow the caliper to pivot and slide, making sure that the caliper and rotor are parallel and in line. As with the Hayes, we were able to set these up without any drag in just a few minutes. The Juicy 7 is compatible with both IS and post mounts right out of the box. The rotor that we received is not the one pictured. Ours is has a wavier pattern, and the brake track has more corners. Actually, I am glad to see that they moved to the style shown, as the rotor is one of the areas we felt needed improvement. The brake was prone to noise and a type of pulsing at the lever that should be alleviated with the new rotor.
The Avid mechanical disc brake packs plenty of power, and the Juicy 7 is every bit as potent. The Juicy outshines its fluid-free counterpart in the area of modulation. The feel at the lever is nice and linear, not grabby. The power was there when you needed it, but in a very controlled manner. Like the Hayes, our complaint wasn’t with power, or modulation, but heat dissipation. Unlike the Hayes, however, Avid offers the Juicy 7 in the medium 185mm size. 160mm is fine if you live anywhere flat, or you never do any sustained downhilling. Everywhere else, the additional 25mm keeps the brakes running cooler for longer, resisting fading. Our only other gripe is with the length of hose that Avid includes... it is long--really, really long. Take the longest fork on the market, put it on the tallest bike, with riser bars, and you will still have plenty of brake line. Seriously. Get the bleed kit, also one of the best ones on the market but at $35 not the cheapest, because you will need it to shorten the lines, unless you are really, really tall. Fortunately, it is an easy job and the bleed kit has all the fittings needed to shorten both lines.
Summary: Both of these brakes had plenty of power and excellent modulation. The Hayes were a little quieter, but with the new rotor the Avid should have taken care of that problem. If you love the look and feel of carbon fiber, but are on a budget, go with the Hayes HFX9 Carbon and don’t look back. We had no complaints with either brake’s performance, but I have to give the nod to Avid as being the better brake. It has features like the pad contact adjust that no other brake has. In addition it has the option of running a 185mm rotor, something that the Hayes cannot do. If you like a good hook at the end of your lever, and like to be able to adjust the feel of your levers, look no further than the Avid Juicy 7.
James Sharp is a contributing editor for GearReview.com specializing in mountain biking.
For more information, contact:
Hayes Disc Brake
5800 W Donges Bay Rd
Mequon, WI 53092
Phone: 1-888-MTN-DISC
E-mail: hayestech@hayesbrake.com
www.hayesdiscbrake.com/
Avid
2875 W Oxford Ave #7
Englewood, CO 80110
Phone: 1-303-762-9353
E-mail: info@avidbike.com
www.avidbike.com
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