Tanglewood Park has one of the nicest mountain biking courses in central North Carolina. I live near the park so I take my morning walks there; often I'll walk the MTB single-track trails on weekdays when few if any bikers are riding the trails. As far as I know this is the only GPS track available for Track No. 3, which is 4.6 miles long and has the most technical features. I'm not a rider so I can't speak to its difficulty rating, but I'm guessing it's intermediate -- reasonably flat with a few small hills and several obstacles to navigate over and around. Trip write-up at Two-Heel Drive.
The trail is marked with red tags -- it's very easy to get lost if you try to get clever and skip over to nearby sections of trail -- those other tracks may wind around in unexpected directions and get you deeply disoriented. Hikers and walkers should avoid the single-tracks on weekend and nights after work, when they get the most use. The park has plenty of places to walk besides the single-tracks (though none are as shady.)I went on a Sunday morning starting out just after sunrise before many people showed up -- later in the day there will be far more riders.