I actually double checked the site we rented from:
Beach Cruiser - 4 Hours $ 10.00
Beach Cruiser - 24 Hours $ 20.00

We did the 4 hours, $20 for two people. You can't do much of anything for that price! This may be an exception on bike rentals, this place makes most their money off renting electric cars. By comparison those little guys are $95 for 4 hours!