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How to Identify and Grade Trails

Difficulty Rating

IMBA have a very nice page on grades of trail difficulty. It's handy to be familiar with this when trying to describe trails or to use as a guide when deciding if a particular trail is suitable for your skill level.

A summary table is this:

	Easiest White Circle	Easy Green Circle	More Difficult Blue Square	Very Difficult Black Diamond	Extremely Difficult Double Black Diamond
Trail Width	2.1m or more	90cm or more	60cm or more	30cm or more	15cm 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 5cm tall or less	Unavoidable obstacles 20cm tall or less	Unavoidable obstacles 38cm tall or less	Unavoidable obstacles 38cm tall or greater
		Avoidable obstacles may be present	Avoidable obstacles may be present	Avoidable obstacles may be present	Avoidable obstacles may be present
				May include loose rocks	May include loose rocks
		Unavoidable bridges 90cm or wider	Unavoidable bridges 60cm or wider	Unavoidable bridges 60cm or wider	Unavoidable bridges 60cm or narrower
			TTF's 60cm high or less, width of deck less than 1/2 the height	TTF's 1.2m high or less, width of deck less than 1/2 the height	TTF's 1.2m high or greater, width of deck is unpredictable
				Short sections may exceed criteria	Many sections may exceed criteria

Full page here:

http://www.imba.com/resources/trail_building/itn...

Here's a few examples of what to expect on each level of trail.

White

As this is defined as a track a vehicle could fit down it would have to be firetrail. Also note that these trails should not have any sections over 10% grade and should be smooth (eg. have no drops or roll-offs). Eg:

Green

Narrower or steeper or with some unavoidable drops of up to 5cm - equivalent of riding up or off the average kerb. Eg:

Blue

Again, narrower and steeper and with larger unavoidable drops/steps of up to 20cm. Eg:

Black

Unavoidable obstacles of up to 38cm - like riding up or off a low sofa. Eg:

Double Black

Unavoidable obstacles of over 38cm. A double black run is most likely to be incredibly steep, technical, with loose surface or all of the above. Eg:

Track Type

On our site we also talk about types of trail. Here's a quick idea of what we mean by the these:

Single Track - Enclosed

Single track is pretty obvious - a trail only wide enough to ride single file.

The enclosed type is bordered at both sides by vegetation or rocks or fences or something. This type of trail is a rider's dream!

Both varieties of single track are also referred to as 'sniggle' (a term that allegedly originates from the MTB-OZ mailing list and a common typo for the work single).

Single Track - Open

Still too narrow to ride anything but single file, but out in the open (with nothing to crash into normally).

Double Track

Wide enough to ride side by side (and often to drive on), but not a full on fire trail or 4WD road (ie. not graded or with a centre line of grass/rocks/etc.).

Firetrail

Trail wide enough to drive a vehicle on with no centre divide. To MTB riders there's no real difference between a firetrail (built by the fire services for access and protection) and other 4WD tracks or forest roads so we classify them all under the same thing here.