Trail rating system
Ratings are "maximum"; ie. most of the trail may be a rating "1", but there may be a difficult obstacle somewhere on the trail that may increase the rating to "3".
1 - Easy; suitable for brand-new riders. Generally wide open and fairly flat, with minimal off-camber sidehills, and the occasional cross-ditch.
2 - Moderately easy; suitable for new riders who are looking to expand their skills. Some minor off-camber sections, hill-climbs, rocks, mud, and other obstacles.
3 - Moderate; suitable for riders with experience. Some off-camber sections, hill climbs, rocks, mud, water, and other obstacles. Some narrow or twisting areas requiring slow speeds, high shelf roads, trees, etc.
4 - Moderately difficult; suitable for experienced riders who are looking for a bit of a challenge. May contain off-camber sidehills, rock climbing, narrow, twisting trails through the trees, steep sections, water crossings, deep mud, and plenty of the usual obstacles.
5 - Difficult; suitable for very experienced riders only. Tough, technical trails, dirt-bike trails, tight squeezes, tires in the air, and lots of obstacles such as large rocks, bottomless mud, or deep water.
Remember, trail difficulty can increase with inclement weather, and trails can become degraded due to landslides, deadfall, and industry. By the same token, a once-difficult trail can become easier for various reasons. Also, because people with varying degrees of experience have written these trail guides, the rating system may differ. A difficult trail for one person may be a moderate trail for another.