Near Rockford and Loves Park, the Rock Cut State Park has great 30 mile network of trails and fire roads. To reach mountain biking at the trailhead, follow US 90 to the Riverside Exit. Head west on Riverside Road and turn right on Perryville Road. After 3 miles, turn right on Harlem Road and continue for 4+ miles to the park entrance.
Overall, Rock Cut State Park is the 3rd most popular mountain bike trail of all 9 mountain biking rides in Illinois.