East of Newport and northeast of San Juan Capistrano, the Horsethief Trail heads up Trabuco Canyon in the Santa Ana Mountains. From the Trabuco Firestation, its an 8 mile mountain bike ride on fire road and singletrack up to the Main Divide Road on the crest. Either continue across on the Horsethief Trail down the other side, head northwest on the Main Divide Road to form a loop, or return the same way. To reach the mountain biking trailhead from US 5 in Laguna Hills, head northeast on El Toro Road (CR18). Turn right on Live Oak Canyon Road and park near the Trabuco Firestation.
Overall, Trabuco Canyon / West Horse Thief Trails is the 18th most popular mountain bike trail of all 132 mountain biking rides in California.