The George S. Mickelson Trail is a great place to ride bicycles and walk or run.  The trail is a operated by South Dakota State Parks and a fee is charged.  Trailheads are spaced along it and most have water and shelter.  Check out all of the activities and buy a trail pass on the Mickelson Trail website. You can also buy a trail pass from local vendors or self pay stations located at trailheads.

Here is an article from Adventure Cyclist about Black Hills Cycling including the Mickelson Trail as part of the route.

Every year there is a 3-day bike ride called the Trail Trek.
The Mickelson Trail is a member of the Rails-to-Trails Conservancy Hall of Fame.