A loop for mountain bikes near Warner Springs takes riders on a combination of sandy fire road and pavement.

Where can you go to do some fat-tire bicycle riding after the winter rains come? Certainly not on many of the county's backcountry dirt roads and trails, which turn slippery when wet. Instead, try out the following 25-mile looping route north of Warner Springs. You'll ride on dirt for part of the way -- on a road carved into decomposed-granite soil, which sheds rain easily and dries quickly.

You can begin this ride at the Lost Valley Road (formerly Indian Flats Road) turnoff along Highway 79, 1.6 miles west of Warner Springs. The first few miles are steadily uphill on Lost Valley Road's narrow, sometimes coiling strip of pavement. The steady ascent takes you through low scrub-brush at first, then through a more interesting mix of ribbonwood and manzanita chaparral. The road swings northeast and then north, and off to the right you get a view of Hot Springs Mountain (highest peak in San Diego County at 6533 feet), looming in the east, about 4 miles away.

After 4 miles you reach an elevation near 4000 feet, where you see, but never approach closely, statuesque Coulter pines on the ridge above. At 6.3 miles, Lost Valley Road veers left and dives down to Indian Flats Campground, a good spot to fill water bottles.

Back at the 6.3-mile mark, a poor dirt road branches north. Take this road and continue north and northwest, staying right at the next fork 0.3 mile ahead. You then descend slightly to where you must cross the willow- and sycamore-lined San Luis Rey River -- definitely a wet, muddy passage, assuming decent rains arrive this season. There's a nice spot for a rest or a picnic just downstream, where the stream cascades over polished rock slabs.

After the stream crossing, you ride uphill along an oak-shaded ravine, and then much more steeply up a chaparral-covered hillside to a 4368-foot summit. The view from there extends across miles of virtually untouched open space. Next, a mile of descent brings you to the paved but very sparsely traveled Chihuahua Valley Road. Turn left and make a breezy descent to Highway 79. Turn left again, climb two miles to the community of Sunshine Summit, and complete the remaining miles of your trip on the gradually descending grade of Highway 79.