Is building fixed gear bike out of old vintage folding bike possible? Our local craigslist has alot of good deals on fairly good condition folding bikes from 60's and 70's for around $40~60...

If it is possible, it would be a perfect summer project

oh, and what parts would i have to buy?

bikes like these($60)



horizontal dropouts.. and i suppose i could use the crank. what would i have to do with the wheels?