Several years ago I had an nice old steel frame refurbished. New Ultegra groupset fitted inc Hollowtech 2 BB and chainset. External bearings.

Flash forward a few years and miles (but not enough miles) and the left BB bearing part unwound itself out the BB on a ride in Wales at the weekend and trashed its threads in doing so. I was hopeful it didn't take out the BB shell threads as well and they seem OK (but not great). I was surprised to find the shell had not been faced (which I thought was essential for external bearing BB) so rang the frame builder/referb guy to ask why, and get his take on why the BB had wrecked itself.

"Ovalised BB" came the reply and "we don't face the BB shell as it takes off the protective paint so it rusts." Cure: £130 new BB shell and £100 repaint. Hmmm, I think. Not sure I want to do that. Apparently heavy use can ovalise the BB shell over years especially if they are not higher quality cast kind.

So I thinks- re tapping threads and fit new BB. Guy says this will not help as the BB will now be oval so the replacement bearings will still only have minimal purchase and the same will happen again.

Anyone come across this? I've read all the usual stuff about re tapping the thread and bearing retaining compount Locktight etc but cannot find any reference to Ovalisation (Ovalization) of the BB shell anywhere. Anyone? Rather not spend £230 just now thanks.

PS Helicoil anyone? or will this mean removing even more of what remains of the BB shell and leave it too weak.