From Evergreen Trail Guide
What does it mean?
The "Grunt Rating" for a trail gives an idea how fit you need to be to enjoy the trail.
This is different from the Tech Rating, which expresses how 'technical' the trail is, i.e. how much skill you need to ride the trail. Although technical terrain is a contributing factor in the ratings because a rider will need to expend more energy on a trail that is rockier or sandy than a smooth hard pack trail. This along with mileage and elevation helps to determine the rating.
Elevation and mileage is self explanatory. However a long climb up a groomed forest road versus less mileage up a steeper hard to climb singletrack trail can influence a trail rating. So it's not just about the numbers, and the corresponding trail difficulty helps in translating how much effort is needed. Whether you burn more anaerobic energy navigating the difficult terrain or even get off the bike to hike, you're still disrupting a steady aerobic cadence.
So with this formula you may sometimes have a trail system differ from one rating to another. This would be caused by the route of which the rider has chosen. As will be common for trail systems like Fort Ebey, Galbraith, Capitol Forest as they are made up of a multitude of trails which can be tailored for a ride with more or less length and difficulty.
Access determines how easy it is to get to the trail. Trails can be accessed right out of a city neighborhood by parking right at a trailhead. Other times you may need to ride on a road or another trail to access. On Remote access it's a fact that most of the time within the duration of the ride you will be in isolated backcountry, where you will need proper gear and fitness. Sometimes on these longer rides you have to commit to finishing the ride out of necessity for safety and survival of yourself, and others in the group.
These ratings are for the most part trails that are not shuttled.
What does each level mean?
|Easy access with minimal elevation change and short mileage of trails.||South Seatac, St. Edwards, Tapeworm, Dash Point|
|Easy to Moderate access with minimal elevation change. Increased mileage and/or difficulty in trail contribute to a higher rating.||Fort Ebey, Lake Sawyer, Tolt-McDonald, Banner Forest|
|Easy to Remote access with elevation change of over 1000'. Mileage generally around 10 up to 20 miles. Possible difficulty with challenging terrain or challenging trail conditions.||Tiger Mountain, Anacortes, Capitol Forest, Lower Big Quilcene|
|Moderate to Remote access with elevation change of over 2000'. Mileage generally around 20 up to 30 miles. Difficulty with challenging terrain or challenging trail conditions will likely be encountered. Long steep stretches of trail or road are common||Devils Gulch, Middle Fork Snoqualmie, Kachess, Noble Nob|
|Generally Remote access with elevation change well over 2000'. Mileage generally well above 20 miles. Difficulty with challenging terrain and trail conditions will likely be encountered. Long steep stretches of trail or road are unavoidable. Approaching or exceeding "Epic" status which is commonly thought of as a ride over 30 miles and/or 5000' of cumulative vert.||Angels Staircase, Icicle Ridge, West Fork Teanaway/Jolly Mountain, Juniper Ridge|