From Vegas, go North on US 95 and exit onto highway 157 (Kyle Canyon Road). Follow 157 to 156 (Deer Creek Road). Follow Deer Creek Road about 4.7 miles to a parking area on the left just after Lucky Strike Road. From the parking area, ride back down the highway about 150 yards (about halfway back to Lucky Strike) to the trail peeling off the highway on the right side. There are multiple downhill options.
In addition to gambling, Las Vegas is home to some top-notch desert mountain biking. The best bike trails in the area include Bootleg Canyon, the Blue Diamond Network, the Cowboy Trails, Little Red Rock Trail, and Mt. Charleston.