Originally Posted by
graveltravel
I don't think there is a drain hole, but I plan on converting this bike to a single speed as soon as I can. Perhaps I'll leave the cable guide hole as a vent?
Sure. But most steel frames also have vents in the chainstays, so if there are vent holes in the BB shell to the stays, a drain hole in the BB is really only important if you ride in the rain a lot.
I was mainly saying you should have a vent hole for the seat tube into the BB shell. The lack of one can cause real rust problems. It doesn't need to be huge, 1/4" is fine.