Mining roads from the late 19th and early 20th century make Crested Butte an awesome destination for off-roading, dirt bikes, and ATVs. Many roads will take you over 12,000 foot mountain passes and through historical camps. Be sure to check road conditions in advance to avoid getting turned around by snow drifts and downed trees.
A couple of great options to consider include Schofield Pass, which offers awesome views of the Gothic Natural Area and Pearl Pass, which will take you to Aspen through wildflowers, boulder fields, and steep climbs. Guides and rentals are available as well: