I've got an SKF Isis BB for my Roberts Audax frame. The sticker on it states I need to fit a spacer as its a 68mm shell. It also states the 73mm shell needs no spacer. So I'm looking for a 5mm spacer, is it the sort of thing my LBS would stock?

The BB shell has previously been faced so its just a fraction under 68mm, will that tolerance be taken up in the preload?

This in itself is a good reason for not having your bb shell faced.

You won't need a 5mm spacer, you'll need a 2.5mm spacer on the drive side,and you could put another on the other side behind the lockring, but it won't strictly be necessary as you can just run the lockring on further.

Coatesy +1

Thanks folks – would these be standard fare at my LBS?

Oh, forgot to mention that your LBS will probably have a drawer full of these, left over from 73mm BB fiitings.