A lot of the trails that we ride on are on professionally man made purpose built mountain bike single tracks, E.g Derby, Alice Springs, Victoria High Country and others. The trails are graded into 3 main groups as per the International Mountain Biking Association (IMBA) of Australia guidelines (link below).
Grades indicate the technical challenges of a track, not the physical exertion required. Green for basic (easy), Blue for intermediate (medium) and Black/Double Black for advanced (hard) grade.
Green circle trails require only basic bike skills and are designed for beginners. Tracks are generally flat and wide with a hardened surface and easily avoidable obstacles.
Blue square trails require intermediate bike skills. Tracks are narrower with less predictable surfaces and feature inclines and/or descents which may include obstacles.
Black Diamond and Double Black Diamond
Black and double black diamond trails require advanced bike skills. Tracks are narrow with unpredictable surfaces, steep gradients and/or feature unavoidable obstacles.