I found a Raleigh Twenty folding bike on the street one day. I thought it was abandoned because of all the rusty parts, but when i got on it and started pedaling, I noticed i was lopsided on the saddle and steering–well, there was practically no steering. I decided to ride the bike home anyways and, not knowing anything about Twenties, I searched on the net. To make a long story short, I have gotten rid of all the components and basically have two halves of the folder and am determined to fix the seat tube that is bent. I want to bring this ol' fella back to life. So here's the trouble:
The seat tube is bent exactly where the down tube joins it. There's no cosmetic damage to the frame, which leads me to believe that the 'accident' probably impacted the seat post and bent the frame here. If you are not familiar with Twenties, see this pic of an almost-stock Twenty:
My frame is bent where you see the cable of this yellow Twenty meet the seat tube, just at the top of the down tube. It is bent away from the chain drive.
Here's the other trouble: in order to bring this bike back to life, I will have to spend quite some cash as this bike appears to be very quirky in its details–quite a challenge for someone inexperienced like me! What that means is I can't take the frame to a frame builder and dish out $$ to true the seat tube, I need to save the $$ for the extinct Shimano BB and Phill Wood rings.
Question: How can I true this tube myself without damaging it? I tried putting it on shims and jumping on it... didn't even make a sound! I am thinking of propping it against a heavy concrete ceiling, shimming both ends, and putting a 2x4 on a car jack and pinning the center of the tube on the other end of the 2x4 and jacking up.
I'd be delighted to hear anything you have to say. This tube is quite stiff and the diameter is about 1.5 in. (the force that bent it must have been tremendous!)