Northwest of Chicago and south of McHenry, the 1,600 acre Moraine Hills State Park has a rolling 11 mile trail system. The crushed limestone covered trails are one-way and color coded. There are three main loops: Lake Definance (red - 3.7 miles); Leather Leaf Bog (blue - 3.2 miles) and Fox River (yellow - 2 miles).
To reach the mountain biking trailhead from McHenry, head south on River Road for 3 miles and follow signs to park entrance.
Overall, Moraine Hills State Park is the 7th most popular mountain bike trail of all 9 mountain biking rides in Illinois.