When I bought a Schwinn bicycle a card came with it for me to enter my personal information, name address, etc. I also had to enter information on the bike, color, size, speeds, etc. There was also a space for the serial number to be entered. It was to be mailed to a division of the police department. By doing this, if the police department retrieved it as stolen merchandise, I would be contacted. If you could get the serial number you could contact local police department to find out if the bike was reported stolen. If you do not want to bother with that, do yourself a favor and get a signed receipt from seller. That way if the bike was stolen you will not be charged with the theft.