Technical Trail Difficulty Rating System

These ratings consider only the technical challenge of the trail, not it's length nor the amount of climbing! They are a simplification of the IMBA technical rating system.

There are a number of characteristics that go into a trail to add to its technical difficult:

Width (narrower is harder)
Evenness of surface (rocky/rutted is harder)
Firmness of surface (softer is harder, eg, sand)
Looseness (it's harder if the rocks move when you ride over them)
Overgrowth (related to width; more overgrown is harder)
Camber (slope across the trail, rather than along it; higher camber is harder)
Exposure (steep and long drop at the edge of the trail)
Steepness (compounds the other characteristics)

Because of the number of factors involved, there's a certain amount of subjectivity to rating trails!

Keep in mind that the T-rating describes the surface of the trail, not how easy or difficult it is to navigate, so the rating remains the same regardless if you are travelling uphill or downhill, regarless if you are on foot, on a horse or on a bike, and regarless of your skill level.

T-Rating	Brief Definition	Surface	Typical Width	Obstacles	Examples
T0	Paved or equivalent	Paved or similarly hard, smooth	At least 4 feet
T1	Mostly smooth & wide	Firm dirt with occasional unevenness from rocks, roots, ruts	At least 4 feet	Extend the surface up or down generally 4” or less	Cheeseboro Canyon Fire Road
T2	Mostly smooth but variable width	Firm dirt with occasional unevenness from rocks, roots, ruts	1.5 feet or wider	Extend the surface up or down generally 4” or less	Two Foxes Trail
T2	Mostly smooth but variable width	May also have loose rocks	At least 4 feet	Extend the surface up or down generally 6” or less	Zuma Ridge Mtwy or upper Bulldog
T3	Predominately uneven surfaces & somewhat rocky	Dirt and rock with frequent unevenness from rocks, roots, ruts	1.5 feet or wider	Extend the surface up or down generally 4” or less	Guadalasca or Space Mountain
T4	Long segments with rocky and uneven surfaces	Dirt and rock with nearly continual unevenness from rocks, roots, ruts	1.5 feet or wider	Extend the surface up or down generally 6” or less	Caballero Canyon, Santa Rosa Trail, Sage Trail
T5	Extensive segments with rocky & uneven surfaces with possible drops & exposure	Dirt and loose rock with nearly continual unevenness from rocks, roots, ruts	1 foot or wider	Extend the surface up or down possibly more than 6”. There may be significant exposure	Little Pine single track, some parts of Bell Canyon
NB	No Bikes. The trail is for hikers and equestrians only; bikes are not allowed
HO	Hiking Only. The trail is for hikers only; bikes and equestrians are not allowed

As well as the whole-number ratings listed above, there are intermediate ratings for trails that fall between two ratings. These trails are more technical than the easier rating, but not as difficult as the higher rating:

T0
T0.5
T1
T1.5
T2
T2.5
T3
T3.5
T4
T4.5
T5

Thanks for looking at Steve's guide to mountain biking trails in Ventura County, the Santa Monica Mountains National Recreation Area (SMMNRA) and other locations frequented by the North Ranch Mountain Bikers.