Well . . . I'm at it again. How about a Cyclo-Cross Bike. Tenative plans are as follows with twin down tubes, top tubes, and split seat tube. I thought the twin top tubes would come in handy shouldering the bike. . . . well it's an excuse anyway to experiement and get rid of some tubing sitting around.
I haven't decided yet if twin tubes will work as crud collectors. On my CD fixie crud does accumulate on top the bottom bracket. I just might make it a fixie project.
But if I don't, so how do I mount a front deraileur to a 1/2" tube. Ahhhh gott'a go old school with one of these. I can make something and have it attach right to the frame.