My own rustbike revival story is not too unlike George's. I was in a friend's used-bike shop one day when a man came in with his little girl and a very nice older (1970) handmade frame, wanting to sell. My friend was overstocked and passed, so the man turned to me, explaining he has owned the bike since new, had raced it in several populaires. As with many of this marque and model, the head tube had been overheated during manufacture and fractured, only to be replaced by a storied framebuilder of highest reputation. The derailleur tab was bent inward several degrees, and there were signs of surface rust that had tunneled under the Imron respray. The seller explained it had sat outside through two winters' snows in the high desert of Central Oregon after it had been passed by in two yard sales. I offered $20, the only cash on me at the time and the seller happily wrote me a receipt and bill of sale with his business card.
The frame then hung in my garage rafters for 17 years while I worked on other projects until I got 'round to it.
Looking at first, I was horrified, figuring I'd spent too much on it at $20! However, the Campagnolo high-flange hubs, crankset, and shifters sale on eBay repaid my outlay about 10 times over. I then examined the frame and saw that while there was indeed rust, all inside was only non-flaking surface rust with no perforations. Most had fallen to the bottom of the bottom bracket, threads protected by the cups. The BB itself was toast, but really nothing was terribly wrong so I flushed the frame, treated it with phosphoric acid, and oily-waxy cavity treatment.
I plan to respray it when warmer weather arrives, but it has built up nicely into my most-favored Fixie. Itrides like a dream on my 200km fixed-gear day rides and occasional bit of single-track. I love this bike for the purpose and wouldn't trade it for something new or "better".
Sometimes, the condition of a neglected and abused frame can be better than it appears!
Best,
Dan.