Before the Chino Hills State Park Discovery Center was constructed we would always tell people to park at Carbon Canyon Regional Park, which is adjacent to Chino Hills State Park. You can park in either place. Personally, I prefer starting my ride in the lush green environment of Carbon Canyon Regional Park where my parking fees go directly to the county I live in rather than some huge park fund that’s mostly used by state parks outside of Orange County. Let your conscience be your guide. This guide assumes you parked at Carbon Canyon.
After you enter Carbon Canyon regional park, once through the “toll gate”, proceed to your left and park by the tennis courts. From there, near the east end of the parking lot, you’ll find a small dirt path that leads along Carbon Canyon Rd, though at least one water crossing, and then onto a fire road that heads south into Chino Hills State Park (Telegraph Canyon).
The Ride Route
View Carbon Canyon to Four Corners via Telegraph Canyon in a larger map
Head up Telegraph Canyon about 6 miles to the junction and turn around. You’ll gain a gradual 1600′ of somewhat up and down terrain, most of which is pretty easy until you get to the last mile. Along the way, you’ll be mostly in a riparian environment similar to going up the Wood Canyon fire road in Aliso Woods Canyon Regional Park.