Northwest of Santa Fe and southwest of Los Alamos, the East Fork Trail (#137) is a 10 mile mountain bike trek through the Jemez Mountains. There are three access points for this trail. The western terminus is at Battleship Rock Picnic Area on SR4 north of Jemez Springs. This trailhead can be very crowded since many hike this section to access the McCauley Hot Springs about 1.5 miles in. The eastern terminus is at Las Conchas on SR4. The mid-point trailhead is at Jemez Falls, and is the most popular for attempting either section as an out-and-back.
To reach mountain biking at the Jemez Falls trailhead from Los Alamos, head southwest on SR502 to SR4. At SR4, turn right heading west for 17 miles. Turn left on the road to Jemez Falls and Campground. The trailhead parking is at the end of the road.
Starting at Battleship Rock, the East Fork Trail is very steep with switchbacks. It will be very crowded with hikers as it climbs 1,200 feet vertical. Once on the plateau, the trail passes McCauley Hot Springs (actually warm, and known for nude bathers) on the way to Jemez Falls. Past the falls, the trail winds through pine forest following a seasonal stream bed. Oak and aspen trees are occasionally scene. After a mile, the route crosses to the north side of SR4 and generally parallels the road. The trail follows a stream with mixed conifer, aspen and oak forests. The route eventually ends at Las Conchas Camping Area.