Singletrack (or single track) describes a type of mountain biking trail that is approximately the width of the bike. It contrasts with double-track or fire road which is wide enough for four-wheeled off-road vehicles. It is often smooth and flowing, but may also feature technical rocky sections, go over tree roots, and include berms, banked turns, switch-backs, hills, drops, jumps, and so forth. Singletrack which descends significantly, and in the most downward direction, is said to be following the fall line.[1]
Many mountain bike riders prefer singletrack over other types of trails, as singletrack is usually designed specifically for the sport, and therefore can have elements which highlight features of the sport (whereas other trail types will usually be more straight, and not exhibit as many hills and other special features).[2][3] Some singletrack includes TTF's (technical trail features) designed to challenge riders, such as log piles, log rides, skinnies, rock gardens, gap jumps, and wall-rides.[3]
Doubletrack (or double track) contrasts with singletrack in that it has two paths, which are approximately parallel. Jeep trails and fire roads are examples of a doubletrack trail.