There are no permits, fees, or registration required for individuals and small groups. You may ride your bike on any forest road or trail unless it is specifically closed to mountain bike use. The closed routes are very few and are well signed. Expect to carry and walk your bike for considerable distances on almost all of the trails on the National Forests. No trails are maintained for continuous mountain bike riding.
Trails are narrow and sometimes steep and are always pretty rough due to rock.
The closure applies to motorized vehicles, not to horses, hikers, and pedal-powered bikes. Expect to share the forest with other users, including hikers, horsefolk, timber cutters, hunters, and bird watchers. A National Forest is a land of many uses and hence, many users. Stay on National Forest land or public roads. Do not trespass on private land.