L.A.'s Mountain Biking Trails Monroe Truck Road Click Here for Map 210 to Glendora Ave. drive north to Sierra Madre turn right. Turn left on Glendora Mtn Rd. Drive to a point right before the road starts switchbacking up the hill to your left. There is a dirt parking area. Trailhead is a few yards up the road. A narrow opening let's you ride around the gate. Beginner Current Trail Rating = 8.5 Click Here to Rate this Trail Click Here to Return to Trails Home