Chino Hills State Park, 13,000 acres of rolling former ranch lands near the juncture of Orange, Riverside, and San Bernardino Counties, is a mountain biker's paradise. Some 40 miles of dirt roadways suitable for cycling trace the park's many shallow canyons and rounded ridges. These routes, plus a number of narrow trails, are suitable for hikers and horses as well.
Telegraph Canyon, on the Orange County side, is perhaps the best route for biking. Twelve miles of round-trip travel, amid grassy hillsides and sycamore- and willow-dotted bottomland, takes you gradually uphill nearly a thousand feet, then back down the same way.
Begin riding at either Carbon Canyon Regional Park, east of the city of Brea on Carbon Canyon Road, or along the roadway just east of the regional park entrance. The popular Telegraph Canyon route begins as a dirt road slanting to the right, off the eastbound side of Carbon Canyon Road. The road dips in and out of a streambed, skirts a small orange grove (yes, there are a few of these remaining in Orange County), and then comes to the base of a hill. There you pick up the Telegraph Canyon Trail, an old service road for former telegraph wires, leading east along the floor of Telegraph Canyon. Within a few minutes, the sights and sounds of civilization fade away, and you'll be pleasantly soothed by the rustle of sycamore leaves, the flutter of birds' wings, and vistas of unspoiled hillsides.
At five miles from the start, well up toward the head of the canyon, you pass under a cool canopy of huge, gnarled live oaks. Ahead lies an old windmill, creaking and groaning in the breeze, and a stock pond filled with cattails. Continue climbing to reach a gap (elevation 1318 feet) at the head of Telegraph Canyon. There you can stop and enjoy a view -- east into San Bernardino County and Riverside County, as well as west into Orange County -- before heading back.