i'll be soon receiving a beat up but intact vintage frameset, which i expect to send off to get powder coated while i work out the details of my next vintage build. before i send it off, i'd like to drill the frame and fork for internal dyno wiring. i know frame builders drill into frames all the time, such as when they add bottle mounts, rack mounts, etc. plus, fork blades and stays often have pre-drilled holes for water drainage and breathing. so, my instinct tells me that introducing a few holes here and there shouldn't significantly affect the frame strength, but i am a little concerned about specifics:
1) i was wondering what's the maximum hole size i should drill before i have to worry about compromising the tubing, structurally (i plan to use rubber grommets, so the holes will be larger than the wiring itself will require). for you frame builders who routinely do this, what size holes would you drill?
2) are there critical areas of the frame/fork i should specifically avoid? for the fork blade, i was thinking about two holes, near the bottom and top, on the inside face of the blade (the top of the blade is sealed with the crown, so i can't route the wire out through the top of the fork blade). the blades each already have two small holes for breathing/drainage. for the frame, i was planning on two holes, one near the top of the downtube, on the underside, and the other on the left chainstay, inside face, near where the fender meets the stay.
in case it matters, the frameset is a touring-grade frameset made with tange 2 DB chromoly main tubes, and tange 5 chromoly straight-gauge stays and fork blades.
thoughts? should i not do it? or am i worrying about nothing?