I don't think the friend is an idiot. You gave him, what, 12 hours to respond to phone call/email over a Friday night/Saturday morning before you decided to snatch up the bike for yourself? Did you warn him that if he didn't respond, the bike would be yours? I think you ought to consider offering the Trek to your friend to follow through on your original gesture of goodwill. That's a win-win outcome, because your daughter already has a bike she's happy with.