Flipping bikes? Maybe 6 per year. Only as favors to close friends and family. Since almost every used bike on the road needs a new chain and cassette/freewheel, figure at least $50 for this - absolute minimum. I probably lose money on average; it is just a hobby.There is no money in this. If you want to make money, become a hedge fund manager. There is no prospect for profit in any part of the bike industry.