I wonder if I should drilll a tiny little drain hole?
Hi mickeg!
Based on old road bikes that had perforated BB shells (ostensibly to reduce weight, rather than condensation), it used to be considered a Very Good Idea to make sure the (then loose-ball bearing) bottom brackets were shielded by a plastic sleeve to ensure the fenderless (without mudguard) front tire did not kick water into the works.
If I were to drill the BB shell, I would also tap it for a bolt to prevent moisture from being kicked into the shell from below while riding, then remove the bolt periodically to allow moisture to drain and condensation to dissipate. I have done this. An o-ring beneath the head keeps it snug and a snap-on socket screw thumb screw cap allows installation and removal without tools. McMaster-Carr usually has them, and sometimes Fastenal or Grainger for US customers. A custom Google search will locate them here:
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=socket+screw+thumb+screw+capIn the early 1980s, a small brass valve was available for retrofit to BB shells. You simply pressed it with your finger and any accumulated moisture would drain, then the valve would reseal after you let go of it.
In 1989, I also drilled and tapped a cyclocross-riding friend's BB for a small valve of the type used to release water from air lines and fuel sumps. It worked well.
Of course, these comments apply to non-eccentric BB shells, like the one on your new bike, mickeg. Post-1985 derailleur bikes often have a small bolt with tapped threads holding the cable guides in place beneath the BB shell. This can usually be removed for drainage and then replaced, as the cable tension holds the guide in place while the bolt is out. I've line-bored such bolts through the socket (usually they're 5mm x 0.8mm but occasionally are 6mm x 1.0) to use as a wire channel for lighting.
All the best,
Dan.
