Trail Difficulty Guide
Our friends at the International Mountain Biking Association have created a stellar rating system for trail difficulty. The IMBA system encompasses trail grade and surface as well as natural obstacles and technical features, and is intended to rate only technical challenge, not physical exertion. BMA has adopted the IMBA ratings for our trail guide, and also provides a more detailed TAC rating for those who really wanna geek out with a combined system for Technical, Aerobic, and Coolness factors.
Do you disagree with BMA's rating choices? We'd love to hear your feedback! Send us an email at trailinfo@bouldermountainibike.org.
Easiest
White Circle |
Easy
Green Circle |
More Difficult
Blue Square |
Very Difficult
Black Diamond |
Extremely Difficult
Double Black Diamond |
|
Trail Width |
72" or more | 36" or more | 24" or more | 12" or more | 6" or more |
Tread Surface |
Hardened or surfaced | Firm and stable | Mostly stable with some variability | Widely variable | Widely variable and unpredictable |
Average Trail Grade |
Less than 5% | 5% or less | 10% or less | 15% or less | 20% or more |
Maximum Trail Grade |
Max 10% | Max 15% | Max 15% or greater | Max 15% or greater | Max 15% or greater |
Natural Obstacles and Trail Technical Features (TTFs) |
None |
Unavoidable obstacles 2" tall or less Avoidable obstacles may be present Unavoidable bridges 36" or wider |
Unavoidable obstacles 8" tall or less Avoidable obstacles may be present Unavoidable bridges 24" or wider TTF's 2' high or less, width of deck is greater than 1/2 the height |
Unavoidable obstacles 15" tall or less Avoidable obstacles may be present May include loose rocks Unavoidable bridges 24" or wider TTF's 4' high or less, width of deck less than 1/2 the height Short sections may exceed criteria |
Unavoidable obstacles 15" tall or greater Avoidable obstacles may be present May include loose rocks Unavoidable bridges 24" or narrower TTF's 4' high or greater, width of deck is unpredictable Many sections may exceed criteria |
