This trailhead is located just across the road from the Chestnut National Park parking center and rest area. Just follow signage across the road from the entrance to hit the start of the trail.
The trail is a dedicated mountain bike trail that is completely man-made within the jungle foliage. It can only be ridden clockwise and is well signed. Throughout the short (~1 mile) loop there are no intersections and such to get confused on. It's very easy to just follow the well-used/worn singletrack.
The mountain biking trail contains several nice bermed, hair-pin turns throughout the course. It also has a few sections that offer both an A and B line that are easy to decipher in order to challenge your skill level.