I also wonder if you could do a sign out sheet with a liability waiver (e.g. I agree it's dangerous, I accept the risk, I will wear a helmet). Don't know anything about Canadian law, though... Do you have someone up there you could ask? (kind of sad this is what you have to think about).

Otherwise, I think it's a lovely idea. Are you OK with leaving it outside? Any theft concerns in your area (I don't mean the people who are riding it, but others). Also probably should think about how to handle disaster (e.g. taco'd wheel, etc).

CA