I spent Spring Break in So Cal this year. Spent 3 days in Palm Desert. On day 2 we rented two 29ers for $135 for the day from http://www.bwbtours.com/
Bikes were in great shape, good service, good deal. Declined a flat tourist road tour ($85 per person) and private guided tour ($175/per person). They delivered bikes to hotel on time. We loaded the van, drove west out of Palm Desert 10 min to Art Smith Trail – trail head is soft sand so decided to drive up Pines to Palms highway in search of real trails. Amazing drive. If my son could drive, I would have had him drop me at the peak and ride down. What a road!
We talked to firefighters about local trails and managed to find one, pretty tough, zero flow, twisty, rocky, cactus all over. Stopped for lunch after an hour of hard riding, then found a motocross track with some fun jumps and banks. We were chased by crazy dogs in a remote mountain neighborhood.
We rode back to van and drove back to Art Smith trail to see if we could find better riding. This is NOT a trail for mountain bikes – avoid at all costs - too steep to ride, too rocky to get any speed. Even riding down was mostly hiking the bikes given the risk of wipeout and constant brake riding. Singletracks reviews give it 5 stars, maybe for hiking, no way for riding. Local hikers thought we were nuts to even try.
We had an enjoyable day to get out in the nature, but not a recommended place for mountain biking. Bring lots of water and sun screen.