Des Moines B-cycle is priced for short rides. 

After joining, you can take an unlimited number of rides during your membership period, and there is no additional charge—ever!—for the first hour of any ride.

Additional fees apply for rides exceeding one hour (see below). 

Think of the user fees as similar to keeping a DVD for an extra day. There's a fee, right? Same with bike-sharing: Keep the bike longer than an hour if you wish, but there's a nominal charge.