We have addapted the international standars to our geography and terrain, classifying the trips as follow:

Basic
Family trips or beginners with basic skills and not well fitness. Easy technical trails and with short time of effort.
Ratio of 2 hours effective ride
Level I
Dirt roads
Less than 1,500 msnm heights
Less than 3 degrees downhill/climbing
Level II
Dirt roads. Goat paths
Less than 2,800 msnm heights
Less than 5% Downhill in short strokes.

Intermediates
Trails technically exigents for cyclists with good training.
Ratio of 4 hours effective ride
Level III
Dirt roads. Goat paths. Singletracks
Less than 3,500 msnm heights
Less than 7 degrees downhill/climbing in short strokes.

Experts
Trails for expert riders. Technical and challenge rides.
Ratio of more than 4 hours ride
Level IV
Dirt roads. Goat paths. Singletracks, downhill/climbing
Over 3,900 msnm heights. Possible carry on the bike.
Less than 10 degrees downhill/climbing
Level V
Goat paths. Singletracks, downhill/climbing
Stairs and trials, very technical and difficult.
More than 10 degrees downhill/climbing
Non consider as tourist trails
Risk of healings and falls down.