A buddy of mine is looking to buy a new crankset. He is considering the FSA SLK crankset. I am trying to steer him towards the FSA K-Force crankset. He can get the K-Force for about $50 more. SRAM is not an option for him neither is the Dura Ace crankset. Of the two mentioned, which is the nicer crankset and why? Also, any K-Force owners experience pitting or rust on the shiney aluminum surface of the chainrings?
Highly rec the new K-force light (with included ceramic BB), but stay away from the SLK versions (unless they have finally fixed the non drive side crank arm loosening issue)
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for $50 extra I would go with the K-Force. I have ridden both cranks, and neither would be a bad choice. The crank arm issue with the SLK can be solved at your local shop. There is a "glue’ that FSA will send the shop to add to the spindle and bolts so they do not loosen (apprently without compromising functionality of the crank). The SLK seems to wobble/bend a bit more (not as stiff) with climbing (same frame and components other than the crank). While shifting under a lot of torque I tended to skip/crunch with the SLK but not the K-force. The price point between the two is so narrow I would say K-Force.
Is your buddy going for the bling, or is he going for performance? If performance is what you’re after, there’s not really a debate over what crank to get; 5 years later, and the Dura-Ace 7800 10spd crank is still the stiffest and lightest crank out there. It may be 20g or so heavier than an FSA, but, it doesn’t flex like a wet noodle like their cranks do!! 
I own both , and I suppose the best bang for the buck would be getting an SL-K and purchasing a Ceramic Bottom Bracket. I am disgusted with the resisted with a Stock MegaExo -
The K-Force definitely feels stiffer, but really the main difference is the K-Force comes with the Super Pro chainrings vs the spider type rings.
The crank arm on the K-Force is definitely wider visually.
The K-Force has been replaced by the SLK-Light
I kept my K-Force and ordered the VCRC ABEC 5 Bottom bracket for 150…awesome setup.
Highly rec the new K-force light (with included ceramic BB), but stay away from the SLK versions (unless they have finally fixed the non drive side crank arm loosening issue)
Definitely an alternate option to my post. Given the OP message though, it sounds as if they are giving him a discounted upgrade on a deprecated part. The K-Force Light is still available , and thus will be significantly more pricey.
It would be cheaper, and ultimately probably more efficient to buy a Ceramic BB -
Just my .02
You can flex a dura ace crank…let alone any crank? Ultegra is stifferthan DA btw.
I have heard the chain-rings on the K-Force will pit or “blemish” with time, due to the finish on the chain-rings. I do not know this personally, but a guy at the LBS said this occurred. Anyone know?
personally would stay away from any FSA cranks due to bad experience with the older K Force, no amount of glue would attach it properly, and it literally came right off while out on a ride (twice). Actually witnessed an FSA crank come right off a racer in a Cat 1/2 race a few weeks ago. No experience with the newer ones.
I really wanted to like my SLK Mega Expo cranks but I just didn’t realize how bad they were until I finally broke down and bought some Campy cranks. I guess I used to think it was normal to have to completely disassemble your drivetrain every so often to coat everything in locktite. Even with locktite and torquing exactly to spec, my cranks would eventually start creaking or clicking as they worked loose.
I did send them in for warranty once and despite getting a new crank arm, fixing bolt and a new bottle of locktite from FSA, it didn’t take long until I had issues again. They are now laying on my workbench and probably won’t go back on a bike. Besides, anyone that had the earlier SLK cranks probably knows about those stupid rubber washers that went between the crank and BB bearing. Those dissintegrated pretty quickly; FSA replaced them (for a fee) with some rubber coated metal rings that aren’t much better in my opinion as they fall apart if you ever decide to take the cranks off.
I’ve heard the K-Force are much better quality so if I had to buy an FSA crank, I’d personally go with that one. All I know is that my Chorus Crank cost the same or less than the SLK one and the quality difference is obvious - it looks better, you can see that the manufacturing quality is better, it installs easier (with no locktite needed) and once it’s on, it never starts creaking, wobbling or working loose. If you want a carbon crank, I’d recommend the chorus UT crank (I’d even put them on a Shimano bike).
There are lots of FSA products I really like but the SLK cranks are one I could do without.
I have heard the chain-rings on the K-Force will pit or “blemish” with time, due to the finish on the chain-rings. I do not know this personally, but a guy at the LBS said this occurred. Anyone know?
I never heard of this before but rumor has it if you ride a combination of Dura Ace crankset on a “rare” Albino White P2K with the appropriate length crankarms it’ll make you about 3 minutes faster. Had you done this last week you would have been the “King of the Smackdown!” With that being said, go order the Dura Ace cranks so I can devote my not so much “free time” to researching something else like ways to keep my “taint” from hurting on the trainer.
may i know where you got this information?
I know there was some test done with the ultegra 9sp vs DA 9 sp cranks but i don’t know of any tests comparing the 10sp versions.
I have heard the chain-rings on the K-Force will pit or “blemish” with time, due to the finish on the chain-rings. I do not know this personally, but a guy at the LBS said this occurred. Anyone know?
Have plenty of miles (over 2k) , and various conditions - no pitting here.
personally would stay away from any FSA cranks due to bad experience with the older K Force, no amount of glue would attach it properly, and it literally came right off while out on a ride (twice). Actually witnessed an FSA crank come right off a racer in a Cat 1/2 race a few weeks ago. No experience with the newer ones.
I have not heard of any issues with FSA cranks in the last year - They acknowledged the issues and sent out a notice to utilize screw cement.
I have not had any issues with any FSA parts.