Dude, riding in the desert just isn't like riding elsewhere. Here area a few keys to getting maximum fun and getting out alive. Live by these 6 tips and you'll make it out of anything alive.
Physical difficulty comes from mileage, amount and difficulty to climbs, and severity of trail surface.
Technical difficulty comes from the number and degree of obstacles, and bike handling skills required.
"Fear Factor" comes from the amount (and degree) of scary stuff. Basically, this comes down to exposure to cliff edges, nasty rock drops, and severity of slope of grade.