First spotted hanging off the Feenstra Felt p/b Kenda team bikes, FSA has steadily been working on the release of their first hydraulic disc brakes, the K-Force (Race) and Afterburner(Trail). Why get into a category that is new for the brand and already pretty crowded? FSA thinks they can do it better, and by first impressions they may be right. The mineral oil based system relies on large 22mm pistons housed in one piece aluminum calipers that are attached to magnesium lever bodies with front and rear specific hoses. Add in carbon levers, some ti hardware bits, and two piece rotors and you’re left with the recipe for what could be a fantastic set of brakes.
Keep reading as we bed-in the new FSA K-Force disc brakes, next!
It was business as usual to mount the K-Force stoppers to my Trek Fuel EX. FSA made sure to send us the right hose length for testing purposes so we wouldn’t have to deal with shortening the lines and the initial bleed is perfect. We’ll get the details on bleeding them in the future, but for now, it seems straight forward with threaded bleed ports on the the caliper and lever similar to Avid and others.
As far as mounting the brake levers with Shimano shifters, the two seem to play nice together without any major interference. The K-Force brakes replaced a set of XT discs which had one major difference in set up – I ran the XTs on the outside of the shifter clamp, while the FSA are on the inside thanks to the longer carbon lever.
Maybe one of the most surprising features of the K-Force brakes is a pad contact adjuster that actually works(!). Out of the box, the levers were out too far for my liking so I used the extremely easy to operate lever reach adjuster to dial them in to my preference. Pulling them in improved the ergonomics, but it resulted in the lever bottoming out too close to the bar for my taste. To my surprise, using the pad contact adjuster barrel you can easily make a noticeable difference to where the lever bottoms out – something that seems to have eluded many brakes over the years. The result is a perfectly set up lever, all without any tools.
Check out Tyler’s post for cutaways of the brake’s internals.
Not that it makes a huge difference functionally, but the attention to detail at the two piece rotor’s carrier is nice with each rotor bolt counter bored into the carrier. The back side of the carrier is relieved to keep the weight down as low as possible which is mounted to the stainless rotor surfaces. The aluminum carrier does help to stiffen the brake rotor.
Brake pads are held in place with a 2.5mm allen screw with a safety spring clip on the end. Inside you will find custom semi-metallic brake pads that look similar in shape to Shimano’s G## series pads for XTR BR-M985, XT BR-M785, SLX BR-M675/666, BR-R785, Alfine BR-S700, Cyclocross BR-CX75 and Road BR-R515 calipers. FSA initially told us that they would be using Shimano style pads, so this seems to confirm that which means replacement pads should be readily available in a pinch.
As Tyler reported, the pad is designed to break in quickly and offer a high coefficient of friction that when combined with a linear piston movement provides strong, but not grabby braking power.
Compared to the weights Tyler logged at Eurobike, our brake sample (still labeled as prototype) is pretty close at 401g for both brakes without any rotors or hardware. The bolt kit has gotten a little heavier since then as the mounting bolts for the caliper are now stainless instead of aluminum, as are the rotor bolts. The rotors weigh in at 102g for the two piece aluminum carrier model in 160mm and 157g for the one piece 180mm Afterburner rotor (one of the rotors we haven’t weighed yet). All together, with every piece of hardware and hoses cut to fit a 17″ Fuel EX, you’re looking at 667g for the complete system.
Impressive. That’s the first thing that comes to mind for the company’s foray into the world of hydraulic disc brakes. Managing to provide the lever feel of high end Formulas or Avids, and the brake pad/rotor feel of high end Shimano brakes, the FSA K-Force hydraulic discs are off to a good start. Light, incredibly easy to set up to your liking, and smooth and powerful out of the box, barring any long term durability issues, FSA certainly looks to have come out of the gate swinging.