Personally I don't let anyone test ride before they put the full asking price in cash in my hand AND sign an agreement that they forfeit it if they damage the bike in anyway. I used to insist that they had full comp insurance until I found out this was pointless as if they crashed the insurance company would make the payout to them not me as the policy's in their name. The cash in my hand was learnt the hard way as a dick test rode my vf750 magna and thrashed the arse of it and damaged the engine and when I sold my runaround lexmoto 125 the kiddy fell of and scratched the side, to be fair he did still buy it (I was very angry and suspect he was abit scared though which may have helped).