fsa K Force Light BB386It looks like the days of chainring standards for high end cranks may be numbered. Following in the footsteps of Shimano, FSA’s new K-force Light BB386 crankset sheds the traditional design in favor of an asymmetric design, only FSA’s still has 5 arms. Hidden behind the crank arm is the 5th bolt, part of a system that was strategically placed in the locations where the pedaling stresses are concentrated. The hollow carbon arms feature a UD finish and hidden bolts and spindle for an improved look and aerodynamics.

Shift past the break for more.

fsa K Force Light BB386 Bolt Pattern

FSA calls the new bolt spacing ABS – or Asymmetric Bolt Spacing which is still apparently built around a 110 BCD, though the spacing won’t line up with a standard 110 ring. Since a rider’s power output is not consistent around the circle, the arms were placed where the points of stress are highest allowing for a super light design that is still stiff. We have already reached out for an answer on this – but if it is based on a 110 BCD then the crank may be able to run both standard and compact rings on the same arm like Shimano’s 9000 crankset. Also, the fact that the crank is only available in 386 is mitigated by the fact that FSA includes bottom brackets that will adapt just about any frame to use the 386 EVO spindle, even threaded.  Update: standard and compact rings will be based around 110 BCD so the crank can run 46/36T, 50/34T, 52/36T, and 53/39T chainring combinations. This is a welcomed trend as riders can change to a compact or even cross gearing without having to buy a new crank if need be. Also, FSA’s new ABS chainrings have new optimized teeth and shift ramps for improved shifting.

The K-Force Light weighs a claimed 584g with a BB386 spindle and will include 7075 aluminum chainrings with alloy T-30 Torx chainring bolts and will be compatible with Shimano 11 speed chains. Arms will be offered in 170, 172.5 and 175mm lengths and in red or black graphics. For more on the crankset check out FSA’s video, which we didn’t embed here due to the auto-play.


  1. redumbdant, too.
    c’mon industry people. We don’t want to buy all this junk that doesn’t work with anything else. even if its 10g lighter or 6.2% stiffer or whatever.
    this kind of stuff will keep people from getting more into the sport. More options, more confusion, less confidence and see ya later. What the hell would a newbie think? I could just imagine some light coffee talk about how daunting a task it is to understand something as simple as a chainring size and compatibility.
    redumbdent. there, you see what i did there? It’s the same message, but not exactly the same.
    LMMAA du frecher kerl.

  2. Hello guys, we’re chiming in to explain the new design. We understand the concerns of new standards and issues associated w/ parts at dealers, etc… Yes there is a negative to new standards, but the result will over come this. Great example is our 386EVO cranks/BB system. Just pick your BB: BB30, PF30, 386EVO, English and soon it will fit BB86… all the while working for all 10s systems (very universal crank). Bottom line is the new design moves material to specific areas of flex to create a stiffer, lighter design. Additionally the rings are forged to further remove material while making it stiffer (improve shifting).

    • Thanks FSA for posting that up. The BB386 is nice in that it works with everything. Also I was originally going to post something along the lines of – who is buying top of the line cranks and then running other’s rings anyways? Unless you are running an Oval ring or similar, there isn’t much point.

  3. One more point guys, this will effect only our top of the like K-Force and SLK. Entry level components will remain the same. If you go to get a part for your car, the mechanic will call the car maker if confused. Consumers can call us as well. Have no fear or technology and better improving products… and yes, it will be a major improvement in performance. Just ask our pro teams who pushed us develop a super stiff design… thanks!

  4. I still haven’t forgiven you guys for pushing PF/BB 30 still!!!!! It seems like a good idea, but after replacing my BB shell several times in the last few years….PF/BB 30 can go to hell! Thanks for chiming in though.

  5. classy…
    A manufacturer actually chimes in and tries to explain, and the FIRST comment is someone bitching about not one, but 2 separate BB standards that FSA didn’t even design.

    Get your facts straight: Cannondale made BB30, SRAM made PF30.

    FSA, being a 3rd party maker, has to play by the rules put forth by the bigger boys.

    Get your stuff together, interwebs…

  6. vhom, understand PF/BB30 can have issues from one frame maker to another. Tolerance is key and can fluctuate between production runs on frames and between makers (USA, Taiwan, China, etc… however frame makers love the additional interface for joining DT/SS/ST to make frame lighter and stiffer. Thanks for your comment bud.

  7. Zach, smaller teams and local cat 1’s do like to play around w/ different rings but for the most part you are totally correct. We sell a lot of after-market rings and will stock the new rings at the same time the cranks come out (compatible: 10s/11s).

  8. It´s refreshing to see a major company commenting in the hellfire of bicycle talk on the internet: BR! Their point is also very clear and simple to understand for any normal human being. New “standards” are the inevitable side effect of any progress. It gives me shivers to think were we would still be, with people determine what companies should build. Less fear and more trust people… if it´s good to stay, it will be for a reason (A-head system, disc brakes) if not, it will vanish soon enough (elevated chain stays, disc wheels on mtb). Oh well, the internet…

  9. I guess there will always be people calling for new standards to stop being created on every level of componentry, but I don’t get/can’t stand the overwhelming whining that occurs when a new product drops that won’t work 100% seamlessly with peoples’ current setups. New technology calls for new standards. Stiffness calls for new standards. Weight calls for new standards. Aero calls for new standards. If you want a beautiful, high-end crank that will fit your BB from 1997, get a White Industries. If you want a racing-level crank that will fit your english shell and all the 5×130 chainrings you’ve stocked up on, get a SRAM. You’ve still got options, people.

  10. Good points Phil and pmurf. These are our flag ship cranks using our latest cutting edge technology. However to be fair, we did make a mistake at the time on the MTB 386 (3-bolt) crankset. It is super light weight but only could go down to a 27t… not good for 27″ or 29″ average riders. The following year, we came out w/ the standard 104/64BCD for these wheel sizes. We do not always get it right but we try. Racers love the MTB 386 cranks and now that SRAM has XX1, the MTB 386 w/ 86BCD works perfect for their new groupo. In the end it worked out to our advantage. Ask bike mechanics about FSA; our goal is to make things that do not usually work together work via adapters or design. We have to follow groups which Shimano, SRAM, Campy develop and make our parts work w/ theirs or w/ all of them if possible.

  11. @FSA USA
    I appreciate the further explanations you provided. There are some benefits and some commonization here, at least with the BB. Fair enough.

  12. FSA. Thanks for answering all the questions. My only concern is shifting quality. My 2011 SLK road crank on my CAAD 10 never shifted like my Shimano Ultegra or Dura Ace cranks. In addition, the extractor bolt (or what ever the center bolt that ties it all together) would come loose all the time and squeak like crazy. I took it out, cleaned it and put lock tite, retorque it down, and I’d still get issues. (Apparently C-dale had several complaints about this issue) My buddy on his C-dale Flash had the same vintage 3 bolt MTB crank and he constantly had shifting issues. When it all boils down, it doesn’t matter how stiff or light something is, if it doesn’t shift properly then the rider will never have a good feelings about it.

  13. fsa….please!!!
    creating solutions for non-problems is their M.O.
    The turn off began with aluminum crown races for headsets…then ceramic headsets (really?), the 4x94mm bcd mtb cranks (when 5x94mm had been around for a decade), the 3 bolt (86mm? bcd) cranks, riser bars that don’t allow controls to be placed far inboard, the wheels with 3 flanges, the carbon armed cranks that developed play in the metal pedal insert, and it just keeps going. now this? full speed ahead is not Shimano. fsa has not created a design that has impacted the market in such a way as to create a new standard…they simply produce products that require proprietary replacement parts. stick to stems and seatpost and try to keep this stuff out of the OE market.
    ps learn a bit from sram when it comes to customer service, especially when IBD are on the other end of the line.

  14. andy, no company is perfect and we do our best. Being one of the first to have a full line of highend carbon components does put us at the forefront and steep learning curve. Carbon technology and composites are rapidly changing helping improve bonding… as well as FSA striving to improve our own engineering and development. I think if we look back at Shimano and SRAM’s history of products, you might find a few “issues” and products we might laugh at now. At one point even Shimano was a small guy taking on the mighty Suntour group and was looked down upon for even trying. Now Shimano and SRAM are the gold standard, but they to had humble beginnings. As far as FSA not creating designs that have impacted the market? I’ll leave that to other people to decide but we feel we have impacted the market in many positive directions. Call us back when you have an issue and we’ll do our best to take care of you next time. If we did not satisfy you past issues w/ one of our products, we apologize. Thanks for your comments and come by to see us at Interbike and meet our tech/warranty manager personally; also, you might like our new stems and bars.

  15. Collin, we are continually improving our ring shifting gates/pins/shape each year w/ many updates. Shimano and SRAM are “tweeking” their systems keeping us on our toes hence all our revisions. I’ll recommend you going to your favorite shops next demo day w/ a brand using our cranks (Energy, SLK, KFL) and see for yourself how much better they shift then your previous experience. Additionally our new asymmetric design K-Force has forged rings and the design itself is stiffer in the highest stress point of the down stroke… you will definitely notice improved shifting and response w/ this new design. Thanks for your comments.

  16. Anyone who has worked in a shop for some time can tell you what FSA stands for – Front Shifting Abnormalities. The stuff is junk, though it might actually improve SRAM shifting. Lord help us whenever FSA finally produces a complete groupset. Given their track record, it should make Rival seem like Dura Ace.

  17. That is such a looser comment (Gravity)… if it was junk it would not be on market. I see the stuff on lots of bikes so I guess lots of other people like it a lot… year after year. You probably have an FSA headset on most of your bikes. My road bike shifts perfectly with my slk carbon crank (Cannondale EVO 2012). You must be a peach to work with all your negative comments.

  18. Whatever the standard, hopefully these carbon cranks can outlast your old ones. I had the dreaded loose carbon/alum crank arm Andy spoke of. A quick call to FSA and I learned my 5 year old cranks were “at the end of their life span”. Yeah….won’t do that again.

  19. The prob with the industry isn’t that there is too many standards of bb’s, even though it is kinda getting redic… the real problem is that when this crank comes out it will retail in the 500 range but some online retailer will put it for 10 bucks over brick and mortar cost no tax free shipping. So when happy go lucky fluorescent jersey hairy leg fred decides he wants to upgrade his tiagra to something more “carbon,” but doesn’t realize these rings aren’t compatible with his 11-43 9 spd cassette and FSA compact FD (remember that beautiful POS!) The shop will end up having to eat the labor and diagnosis, while he returns and re-orders another POS crank from PBK (or similar) and the shop makes zero money…

    That’s a best case sceenario… the more likely case is that the fred installs the crank himself, then the left arm falls off like in the early k-force days. then fsa puts out a notice (dear shop, this is your fault b/c you need to install new blue compression washers every time you remove the crank). Followed by another notice (dear shop, still not our fault, you should have installed the blue compression washers and goldenrod loctite, which we won’t start to supply you with till much later). Finally a wave washer is added to compensate for the different shell spacing etc and things get slightly better.

    Overall Experience, if you put this on Ultegra/DA or Campy Chorus/Rec/SR, you are making a significant downgrade in your shifting performance… FSA is compatible but not perfect, Shimano and Campy design a group around itself, and you will have best results keeping everything together as intended by the designer. Sram and FSA will prob match better 1/1 shifting is a lot less picky and there seems to be more power behind each shift with less precision.

    okay now that the negativity is out, FSA pushed carbon components while the big group manufacturers lagged behind. Their ideas have always been great, they just are week in execution, and product testing etc. It’s likely that 5 years from now the big 2 will go to an asymmetric design, learning from FSA’s mistakes and will create a better, stiffer crank with rings that shift, and left arms that don’t fall off. I’m not in a hurry to get stuck on the side of the road, so I’ll prob wait it out.

    Shop guys are gonna agree with me, fred nation is gonna tear me apart… can’t wait for the comments

  20. I think FSA crankarms have some quality construction for the money and good technology behind them, but looking at my bike as a complete system, it never felt like it was that great with FSA cranks on them. I do have FSA headsets on 2 of my bikes, which have not given me any desire to upgrade/swap out. I haven’t taken the gamble on FSA BBs yet, but the stories of their sealing aren’t very confidence inspiring. I will give FSA another chance with the megatooth 1x ring… if that doesn’t solve my chain drop issue on my Ti 29er, I’m sticking to more reputable cranks.

What do you think?