Having read various articles on the internet stating a Shimano BB would work with an FSA alloy crankset I bought an Ultegra BB for my road bike… foolishly I didn’t think to compare the BB cups before installing but to my disappointment the FSA crank axle is a smaller diameter than the Shimano and therefore the combination doesn’t work.

Did I buy the wrong Shimano BB? Or is it an incorrect myth that Shimano BBs work with FSA cranks?

(The crankset is an FSA Omega)

Not a myth i’m rumming fsa cranks in a shimano bottom bracket, the fsa omega bb axles are 19mm not 24mm so you need the specific 19mm omega BB.

Fsa are a pain in not Useing the same bb for all there chainsets
You were a little unlucky

That would explain it – thanks! At £30 to £40 quid for the FSA BB I decided to buy a Tiagra crankset for £60.