What happens if you try and fit a 70mm square taper BB in a 68mm shell? do the cups just seat down on the BB whilst still having threads proud of the shell (say 1mm on each side) – is that really a problem?

No such thing as a 70mm shell, I guess you mean 73mm? you would need to space out the difference, what might be a problem is not having enough thread left going into the frame.

No such thing as a 70mm shell

Durrr, Italian, back of the class.

Dunno, TBH Stoner, suck it and see. Can’t think that it would make a huge difference, you could space it out. I’ve used cassette spacers behind cups before

aha – Italian’s not going to work with a standard ISO/British thread then is it?

bloody continentals!

cheers for the info guys.

i think italian thread bb’s are a different diameter anyway, as well as both left handed? it wont work anyway basically.

I had a titanium GT Xizang with a 70mm BB. conventional thread.
I used a 68mm cartridge BB and it worked fine