Dear JACUSTOMER - Based on these facts you do not owe anyone anything. They breached the contract by not paying and since the bike remained in your name and they were making payments it would legally be considered the same as a rental or a lease regardless of what you called it. I'm not certain of all the terms of your agreement but theoretically you could file a suit against them for the rest of the rental payments.
I doubt that it would be worth your while to sue them but if they sue you then I would file a counter claim for the balance of the rental payments. The buyer breached the contract, not you so I don't think there is any question that you are correct. If this goes to small claims court you can hire an attorney if you wish but most attorneys will not practice in the small claims court and would remove the case to the general court system.
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