Bent Creek is the go-to trail system for the greater Asheville area, and with the deeply-ingrained mountain bike culture in the Asheville/Brevard area, and Western North Carolina in general, Bent Creek sees a ton of traffic. There are several different trailheads and ways to access the trail, and many weekends all of the trailheads are all filled to overflowing. Cars that can't fit into the parking lots line the nearby forest roads, and Lake Powhatan Campground is usually filled as well. This might be the busiest mountain bike trail in North Carolina... and as you'll see if you ride here, there's a good reason for it!
The trail system is composed of two very different areas: a flatter area, and a much more mountainous section on the ridge.
There are numerous singletack and doubletrack trails in the lower, much flatter areas near Lake Powhatan. These are great beginner trails or warm up/cool down sections. These segments include Deerfield Loop, Explorer Loop, Homestead, Lower Sidehill Trail, Pinetree Loop, and others.
If you're looking for a climbing challenge and/or some killer high-speed descending, the place to go is definitely towards the ridge. Green's Lick is the widely-renowned descent, and if you're riding here, you have to ride it! Green's Lick is very fast, flowy, jump-filled, full of massive berms and wallrides to rail (even bigger than those on Ingles Field Gap and Wolf Branch), a few rock gardens, several technical rock features, and offers absolutely no respite until you reach the bottom!
Other trails on the ridge that work well as climbs or descents include Ingles Field Gap, Wolf Branch, and others.