Southwest of Denver and south of Pine Junction, the Buffalo Creek Trails System is an outstanding network of singletrack. The trails roll through ponderosa pine forest, much of which experienced a forest fire several years ago. The trail tread is predominately decomposed granite (i.e. crushed gravel) that drains well, but can be very loose at times. The trail system consists of several singletracks of varying difficulty and can be combined to form endless loops. Make sure not to underestimate the length of these trails -- start with small loops and then work outward, especially in the exposed heat of mid-summer.
A nice stretch of the Colorado Trail passes through the middle of the Buffalo Creek Mountain Bike Area.
To reach the trailhead from Denver, head west on US285 through Conifer to Pine Junction at milepost 229. Turn left heading south on Pine Valley Road (aka CR126) for 5.8 miles toward the town of Pine. Turn right heading west on Crystal Lake Road for 1.4 miles to the Pine Valley Ranch Park, which is located at 30400 Crystal Lake Road.
Overall, Buffalo Creek Mountain Bike Area is the 4th most popular mountain bike trail of all 176 mountain biking rides in Colorado.