Des Moines B-cycle is priced for short rides.
Trip time differs depending on the kind of pass purchased. The multi-trip pass has free first half hour rides, with additional charges accruing after the initial 30 minutes. The Monthly & Annual passes have free 60 minute rides, with additional fees beginning to accrue after one hour.
Think of the user fees as similar to keeping a library book for an extra day. Keep the bike longer if you wish, but there's a nominal charge.
Please note that applicable sales tax will be applied to all memberships and usage fees.