Hi,

I have an FSA SL-K double chainset with a Mega Exo BB. My bike has a 68mm shell, and the BB is for a 68mm shell also.

When I assemble the Cranks into the BB as per the instructions (Correct torque, no spacers) the chainset's axle appears too large, or the BB cups too thin. When the fastening bolt is fully home, there is still lateral movement in the cranks.

For a short term fix, I have introduced a spacer in between the BB shell and the external cups. However I do not want this to be permanent as it's offsetting my Q-Factor.

My question is; Have I purchased the wrong BB?


or,

Is my chainset for a larger BB shell for some odd reason?

Anyone maybe have some insight on this?

Can the wavey washer take up > 2mm clearance?

Here's their FAQ on the subject:

https://www.fullspeedahead.com/faq/96...E-TO-SIDE-PLAY

I really don't like their setup at all.

Had the same problem once with an FSA crankset a few years ago, returned them to the shop where i bought them and went campy squared tapper. I remember all the pieces were in the right place, nothing looked wrong, but i had that play, everything was new too. Non sense.

Good luck.

Thanks for the link, although their information is pretty useless. I dont know any sane person with any sort of remote common sense who would not check that all the small bits are there. It's the first thing I checked.

As for the design, it seems pretty awful. Shimano's setup is so much more simple with the preload then pinch screws. None of this spring washer for preload and a bit bolt that comes loose all the time. Very disappointed in this tbh.

I'll get a new spring washer and hope the tension will be able to take up this 'slack' and loctite the threads to stop it coming loose.

I'm not familiar with these FSA cranks but the picture you show has "BB-70/68" printed on the bb shell. I wonder if the bb is made to fit both English (68 mm) and Italian (70 mm) frames and comes with the appropriately threaded cups but requires a 2 mm spacer if used on an English shell.

One thing I noticed was that the Non drive side cup was thinner than the drive side cup, but didnt seem to be thinner to the extent of 2mm.

Currently I have a 2.5mm spacer on the non drive side, but I think you could be correct. I'll look into it with the BB a little more. Maybe measure the overall distance with this BB in the frame and a normal Shimano hollowtech BB (The cranks work in a shimano BB)