Does anyone know the inside diameter of an american BB, i think that i have one on my bike but you know i jus wanna make sure before i part wit any more of my hard earned.
any help much appriciated.
thanks

http://en.wikipedia.org/wiki/Bottom_bracket#Shell_diameters_and_threading reckons 51.3mm

thanks it looks abot 2" ill have 2 go measure. i cud b really precise and use verniers (yeah right).
well thanks it was well nice of u.

If it looks about 2", then it's an american BB.
-Bill