West of Grand Junction and Fruita, the Rabbit Valley Recreation Management Area has miles of mountain bike trails to explore. The trails vary from buff singletrack with some sandy or rocky sections to packed/sandy double track. In the eastern half of Rabbit Valley, there is the popular Rim Trail which has been pretty beat up in the past couple years from motorcycles. In the western half of Rabbit Valley, there are the popular East Rim Trail and West Rim Trail which are still pretty buff and are the favorites with most bikers.
To reach mountain biking at the McDonald Trailhead from Grand Junction, head west on US70 to Exit #2. Head south on access road generally staying to the right. At about a mile in, the road forks -- follow the left fork which is signed with a large caution rough road ahead (its actually easier than the right fork). Continue for about 3 miles to the signed McDonald Trailhead parking area.