FSA Afterburner Disc Brakes

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Review by Joe Schneider // Photos by Brandon Turman

FSA, a trusted and known brand for cockpit components, has now entered the hydraulic disk brake market. This stirs the pot and adds another player to the fray of manufacturers on the quest to make the ideal set of brakes. FSA has two versions of their hydraulic disk brake set, the K-Force and the Afterburner, both have the same functions but the K-Force drops 40 grams per side from the system. This review is on the Afterburner model which lists for $289 per side and weighs in at 345 grams for the front with a light weight rotor and rotor bolts.

Afterburner Disc Brake Highlights

• Reach Adjustment on the Lever
• Stroke Adjustment on the Lever Body
• Ambidextrous Aluminum Lever Body / Master Cylinder
• Aluminum Lever Blade
• Mineral Oil
• Front and Rear Specific Hoses
• One Piece Forged Caliper
• 160mm or 180mm Rotor Options
• Top Loading Semi-Organic Pads with Aluminum Back Plate
• Compatible with Shimano XT/XTR Brake Pads
• Slim Aluminum Pad Retention Pin
• Weight: 345 grams per side
• MSRP: $289 per side

Initial Impressions

Before I received the brakes I was curious what level of quality FSA was aiming for. The pictures looked good, but you can’t judge a book by its cover. The first thing I noticed was that the weight is in check, which impressed me. The contour lines on the lever / master cylinder and the caliper are optimized to remove extra material and give them a unique appearance.

The installation couldn’t have gone better. The guys at FSA took care of me and precut the lines to the proper length and everything I needed was included in the package: brakes, rotors, hardware, adapters and a bleed kit. The lever fit the bar diameter very well and the post mount adaptor and bolts installed without any hick-ups.

All the bushings in the lever pivots were tight and the adjustments crisp. The reach adjustment knob is on the lever blade close to the main pivot and the stroke adjustment is the red wheel nestled into the master cylinder. Both have detents and click when they are turned, and the range of motion is actually wide enough to fit a very diverse group of hand sizes.

On The Trail

The lever feel was encouraging during installation, and this did not change once I got rolling. The brakes felt very natural which let me get comfortable with them quickly. By the time the pads were done bedding in I had completely forgotten I was on a new-to-the-market set of brakes. I will admit, the first trail I rode was steep and pretty sustained. Regardless the pads were quick to settle into the new rotors. One more factor which helped me become comfortable quickly was the adjustability of the lever reach and throw. I was able to dial in each setting just the way I like it, close and short, and I still had a couple clicks of adjustment left. Throughout my time on the brakes I did fine tune the lever adjustments while on the trail. The clickers are small and out of the way, which is how they should be. They are adjustable with gloves on, however to actually feel the clicks and keep the levers adjusted the same it is best to take the time to remove your gloves.

The stopping feel is assertive. They are as powerful as they need to be without being too grabby. The engagement of the pads is quick but linear with the rest of the stroke. FSA’s lever cam design is less aggressive getting to the initial pad contact than Shimano’s servo wave found in the XT and SLX levers. On the dirt this means FSA’s design is less prone to locking up the wheels when you first pull the lever, especially if you are light on your wheels over a roller or flicking into a corner. Initially I thought it made the brakes not feel as lively, but once I started riding, I found I gained a noticeable amount of light braking control. It added a new dynamic to my braking technique which was more significant than I gave it credit for. Once past the initial pad contact, the power ramps up quickly and evenly. They stop when you tell them to stop. The power is ample for whatever strength of braking required. The levers easily and naturally pull to the exact spot they need to be for the perfect amount of power needed at that split-second moment.

On top of feeling powerful and modulating well the front and rear levers have a remarkably matched feel. FSA spec’d different brake hoses which are specific to the front and rear; the rear brake line is stiffer than the front. This is significant, and here is why on a technical level: when you pull the lever it pressurizes the hose, which causes the hose to expand. This expansion takes up some of the brake fluid needed to push the pistons. Because the rear hose is longer than the front, it needs to be stiffer if you want it to behave like the shorter front hose in terms of overall volume of oil displaced by the hose expansion. A stiffer hose in the rear makes the volume of fluid taken up by the two hoses much closer to the same, which in turn causes the levers to have a very similar feel. Initially I ran a smaller rotor on the rear wheel, but midway through the test I upgraded the rear to a 180mm rotor to match the front. Having the same rotors really proved to me how similar the front and rear brakes feel. It’s a complaint I never knew I had, almost like having the volume controls for the car’s stereo on the steering wheel - I didn’t know what I was missing until I got it. My personal preference is to run the same tires in the front and the rear; I like the predictability and control it gives me when I move around on the bike. Having the levers feel the same has the same effect, and for this reason I would highly recommend staying with the same size rotors on the front and rear wheels.

The lever perch is stiff. Once mounted to the bars there is pretty much zero flex when you pull on the lever, again adding to the solid feel of the lever. The perch is also reasonably low profile; it snugged up as well as I could have hoped for next to my Reverb lever and Shimano shifter.

Out of the box I did experience some pump, not surprisingly but more so in the rear brake than the front. The FSA bleed kit contains FSA's blend of mineral oil and a syringe setup similar to SRAM’s, plus a small pamphlet with instructions. The instructions had pictures and concise sentences, written in English as their first language. The procedure was pretty standard and the bleed steps were easy to follow and perform. I was able to find some air in the master cylinder, which may have happened when the lines were cut to length.

Things That Could Be Improved

Sometimes after sitting for a while in the garage the first couple of pulls on the lever can feel inconsistent but then things even out. The semi metallic pads can also occasionally feel inconsistent through a revolution of the wheel until they get some heat into the system after a couple of good hard pulls.

Initially I had a 180mm rotor in the front and a 160mm rotor in the rear. The rear regularly was a victim of the standard lever pump issue from heat expansion that many mineral oil brakes experience. After an extended scrub of speed, then a quick release and back on the brakes, the lever would engage further out from the bars (shorter stroke). Discussing the issue with FSA, they recommended I up size the rear rotor to match the front in order to help with heat removal and they also had me push the pistons all the way back into the caliper then bleed out the little bit of extra fluid in the system. The upsized rear rotor made a notable difference in keeping the heat dissipated and increasing the braking power. On more sustained descents the system still will pump up a little bit, but the brakes were always still operable, the lever just lands a touch further out than when you are sitting in the parking lot. The performance has stayed pretty consistent for me when this happens; I always keep riding without any issue. On more pedally trails or ones with more intermittent braking, the pump effect never occurs. Between the two fixes and the bleed the brakes performance is right where it should be. The absence of a 200mm rotor indicates that FSA aimed squarely at trail riding with this brake, and that goal matches my experience with the brake in the field.

Long Term Durability

It takes a year and several sets of brake pads to really know if a brake will develop any real long term problems. I've not been on these brakes that long, but to date I have not had any issues, and that still a good thing. The lever linkage and the materials seem robust. Hopefully FSA gave the notorious sticky caliper piston issue some serious consideration because it has been the downfall of many great sets of brakes. If they have addressed that particular concern, then these should be trouble free brakes until you sell your bike.

What's The Bottom Line?

Based on my experience FSA has come to market with a very competitive product. They kept the end user in mind with their design choices. They encompass the features and weight of a high end brake and provide a powerful balanced feel. These brakes are a great upgrade for your shorter travel full suspension mountain bike.

Visit www.fullspeedahead.com for more details.

About The Reviewer

Joe Schneider grew up in Durango, Colorado. Beginning in 2002, at the age of 13, he started riding mountain bikes and racing in the local race series. One thing led to another and he eventually made it into the mid-ranks of the pro cross-country field. Collegiate racing shed light on technical riding and he began to pursue longer travel bikes and most recently dirt bikes. He enjoys smashing through rocks or getting loose on flowy singletrack. Ultimately the alpine shuttle is his favorite, with a couple thousand feet of climbing and two or three times that in descending. He is currently a Mechanical Engineer who designs tools to blow things up. He loves to ride snowmobiles, motos, and mountain bikes whenever possible with his lady and many good friends. As a practiced mechanic, he enjoys spending the remainder of his free time fixing and maintaining all of his rides.