West of Santa Cruz, the 4,000 acre Wilder Ranch State Park has a winding, rolling 10 mile mountain bike loop. The loop combines singletrack and fire roads through chapparal hills, redwood preserves and eucalyptus.
To reach the main Wilder Ranch State Park trailhead from Santa Cruz, head northwest on US1 for a couple miles. There is a signed state park entrance on the left with a large parking area just past the guard house. Alternately, there is plenty of informal roadside parking just before the state park entrance on US1.
The trails roll down to the coastline and climb high up into the hills above. The hill side trails connect with the UC Santa Cruz campus trail system at Empire Grade Road just north of campus (no parking).
Overall, Wilder Ranch State Park is the 8th most popular mountain bike trail of all 132 mountain biking rides in California.