In the Shasta Trinity National Forest, this challenging 70 mile mountain bike ride on singletrack and dirt roads crosses over the Sacramento, McCloud and Pit Rivers as well as dozens of creeks and streams. Begin at the Dog Creek underpass at 15 and take Forest Route 34NI7 to McCLoud Bridge where it runs into FS27. Follow 27 all the way to the gravel road at Potem Falls. Follow the gravel road to 34NO2 to Sagehen Hill where it becomes an unmaintained road and goes along Backbone Ridge. The road becomes Bear Mountain Road (County 5HO4) at Jones Valley. It is possible to follow Potem Falls Road out to Hwy. 299 at Round Mountain and follow the highway back to Redding.
To reach the mountain biking trailhead from US 5, exit north of Shasta Lake onto Dock Creek.
Overall, Three Rivers is the 73rd most popular mountain bike trail of all 132 mountain biking rides in California.