Trail wide enough for one rider.
n. trail just wide enough for one person or bike -- the mountain biker’s holy grail.
an off-road trail wide enough for a single cyclist only (A dirt road cut by on ATV would make two ruts, a doubletrack).
1: Usually a narrow trail best suited for mountain bikes, as opposed to a double track, which is usually a trail intended for truck use. 2: Singletrack trails are known as the most challenging and fun trails in mountain biking.