So, I'm looking for a pursuit track bike. I was searching around on the net, and came across this:
How difficult would it be to build a frame with wavy tubes like that? How much different would it be from building a bike with straight tubes? What would have to happen to the lugs?
thanks so much
ps. If you have a bike like that that you are looking to sell, I'm 6'2, drop me a message
Depends on if you actually buy the tubes already shaped like that OR if you bend the tubes like that yourself. There are techniques that I've read involving bending with heat and sand. This stuff is entirely way too advanced if this is a 1st frame learning experience. You should do a search on the framebuilder's listserve because I recall a discussion about this ages ago.
You should be able to use regular head tube lugs, as long as the top tube meets the head tube roughly horizontal (like a regular frame). The seat tube lug and BB shell are a different matter. You might be able to cold set them, but I doubt it, the angles are just too steep. You would probably be better off fillet brazing these joints. I know you can get a BB shell with lugs for just the chainstays, allowing the down and seat tubes to be attatched at any angle. You can also get seat collars that are 4 or 5 inches long, so the top tube would join the collar, not the tube (see www.ceeway.com).
As for the tubes, I've no idea where you could get some, or how to bend straight ones. Maybe ask your local friendly custom motorcycle shop if they can bend tubes.
cerrobend and TIG welding are your friends.