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?