What is the Grunt and Gnarl factor?

Every trail in our directory has a grunt and gnarl factor calculated, to give you an indication of how demanding and technical the route is.

The Grunt Factor is a measure of how demanding a run is. It takes account of the distance, the nature of the terrain, and the nature of the trail. The higher the number the more demanding it is. 75+ is considered Extreme.

The Gnarl Factor is a measure of how 'gnarly' (technical) a run is. It takes into account the nature of the trail and how steep it is. Lower scores indicate non-challenging running while higher numbers indicate technically difficult running. Bear in mind that it is an average for the whole run - there will always be harder and easier sections.

You'll find these on the specs of every trail in our directory.​