I did mention it on post one as the important bit of liability insurance.
Two P2P bike rental platforms I found were Apiko and Spinlister, neither really operates in the US. Europe, India, China, they have a wide range of P2P bike sharing platforms.
Spinlister is a good example of what I hope will eventually get established in the US; their fees are reasonable, include a basic insurance coverage, and allow the renter to purchase additional coverage. With a service line that it could be as simple as listing bikes in the platform. You only incur in costs if the bikes get rented.