FSA crankset installation

psychle

It's been nearly fifteen years since I last assembled a bike so I'm hoping you guys can help me out with some of the intricacies of modern componentry.

I've installed a FSA SLK Pro chainset with Mege Exo BB, or have I?
I've put quite a bit of force through the installation bolt but the end of the splines are still (just) visible.
Does this look far enough on or should I be putting even more into it? And if so, how much? Just enough to hide the splines or should the wavy washer be almost flattened?

huuregeil

That looks like mine. The wavy washer shouldn't completely flatten. I used a torque wrench to make sure things were right.

psychle

Torque wrench! We never bothered with things like that back in the day

Conceptually I have a problem with relying solely on a torque measurement. Surely the actual position of the crank on the axle is quite relevant, in terms of designed Q-factor at least? And possibly even chainline?

Another thing I noticed was the ease with which the one-piece drive-side crank/axle assembly slid through the BB cups. The tension in the wavy washer is all that is maintaining the lateral position of the whole assembly. Is this some kind of self-centring mechanism?

Fixed cups, adjustable cups, lockrings, loose bearings and square tapered axles were much simpler to understand.

huuregeil

But for those kind of taper fits, torque is an equivalent or even better measure. The difference in Q-factor in, say, 10% torque variation is going to be miniscule.

Yeah, essentially this BB arrangement needs the cranks to provide the lateral locating in some way. A wavy washer - which is actully quite strong - works as well as anything else.

The cranks are great btw, don't let any of this unnerve you, I've had about 2500 problem-free miles on mine.

tartan_army

Came on to do a bit of a search about isntallation of FSA SLK Pro cranks and this thread came up.

I can barely get the left crank on more than about half to three quarters of the way down with loads of the splines still showing. The fit just seems absolutely impossible. Got it about three quarters of the way on while off the bike but then took me two days and multiple attempts to get apart again, seems like if it goes on it'll never come off again!

I know FSA have had bad reputation in the past for crank bolts coming loose, falling off etc. Do you think they have changed the fit too far in the opposite direction now and it's too tight?!!

Anyone else had this problem?


I know FSA cranks have a bit of a bad reputation but took a punt and seems to be backfiring!

jairaj

I had similar problems with FSA mountain bike crank that uses almost the same fittings. i could only get it on 3/4 of the way onto the splines, when I took it out I realised the axle was cutting into the peddle spines as there were some small burrs.

In the end I had to very gently file away the burrs and re fit the crank would go on a few more mm onto the spline. I kept repeating the procedure many times being very carefull to only file very little.

After fecking ages and using a LOT of force on the bolt, you need a long lever, the cranks fitted tight and fully on the spline. Been riding on it for over a month now and no issues so far.

tartan_army

But sounds like it's never coming off again jairaj!

Don't see why I should be having to file a brand new product to get them to fit together!

Anyone else had same problem with road cranks, particularly SLK Pro?

jairaj

The crank removes fine using the self extracting bolt as per normal.

The only reason I did the filing was the crank was a discontinued item at a MASSIVE discount. The shop said if it was faulty they'd give me a refund as they couldn't get another one and I didn't want to miss out on the bargain.

But if I paid RRP then it'll be straight back to the shop asking for a new one or help fitting. Do note the Torque figure quoted for my crank bolt was quite high (+50Nm I think). My torque wrench only goes up to 25Nm and that required some heft. So you will need a large lever or big muscles.

jthef

had the same problem with mine, ended up at LBS to fit it.
It has come louse a couple of times now so put some thread lock on threads and more of the supplies lock tight on the splines.
Not he easiest fitting, but works fine

tartan_army

Ok so the self extracting bolt should help to drive it back off when needed. Not used one of them before as not been able to get it on to take it apart yet!

Am trying to avoid taking it to shop as wanted to try and fit myself but may have to resort to this.

It comes supplied with loctite on the bolt now, think this is recent addition.

jthef

The other reason I took it to the shop was the price of the tool to fit the retracting cap thing
talk about rip off :evil:

tartan_army

Yeah cheapest I can find it for seems to be 9 quid and have realised will probably cost a tenner for LBS to fit. Wondered whether it would be useful to have tool though for when it needs to be kept being tightened up!

jairaj

just use some needle nose pliers, job done.

tartan_army

Ok so that works? Cheers, I was wondering if just spinning it round with a couple of small screwdrivers as long as it was really pushed tight would work.

Maybe will give it another go on the bike then, see if there is anything to file off and take to lbs if needed.

Very frustrated as has been a right farce getting the left crank bolts/ washers etc of the (very well known on here) supplier in the first place.

psychle

I feel obliged to respond to my old post

After taking the photo I put a little bit more effort on the installation bolt and got the crank on another mm or so and decided to leave it at that and just keep an eye on it.
I've now done a few hundered miles since completing the build and everything is working just fine, no signs of any loosening and the cranks and BB feel suitably solid for my meagre power output.

I fitted an FSA K-force just over a year ago (no wavy washer) to another bike. I just screwed on the extracting cap by hand and having done a couple of thousand miles on that, the cap is still in place. Remember the cap is under no force until you are extracting the cranks so it's only vibration that would cause it to come undone. A little threadlock should ease any such worries, or just leave it off until you need it?

Meds1962

My Truvativ rouleur chainset is exactly the same, no wavy washer provided with it but I've had no problems.

I'm not overly impressed with the mega exo bb though.

Richard-Dublin

I installed my FSA crank set and BB using a torque wrench and I was amazed how much effort it took to get to the correct torque value. No problems since though. There are a lot of threads on various sites about FSA cranks coming loose so probably worth making sure it's properly tightened (Loctite is also recommended)