I have only started selling... I have been collecting for years. I see no reason to offer returns. I am upfront with the condition and I ask questions of the prospective buyers. If they are satisfied at the time they hand over the cash, they are the new owners of the bike. If they realize that they missed something... too bad. I don't hide anything. I haven't gotten any requests for a refund, and I never expect to. CL is not a store, it is an "as is" public market place. Don't give your money to anyone unless you are satisfied with the item.
I have never asked for a refund for something that I have purchased. That part of the deal should be worked out before the cash moves. Are there guarantees in life? No.