Why are the trails in Breck less steep than other MTB hot spots?
Though you wouldn’t know it by the recent stretch of beautiful days, it’s almost the end of mountain bike season here in Summit, as well as the end of my highly professional career as a mountain bike columnist. One thing I haven’t talked too much about is trail building and design.
If you’ve ever volunteered for a trail project — and I hope you have — you’ve probably heard some of the trail nerd jargon: Back slope, out slope, cross slope, critical edge, grade reversal, vertically stacked rock armoring, flow, buff, gnar, chunk, tech and, my personal favorite, rolling grade dip (rolls off the tongue like water off a trail).
All these terms actually mean something. How you incorporate all those things into the design of a trail affects not only how it rides and the kind of experience it provides, but also how well it stands up to the depredations of use and weather. A well-planned and well-built trail will stand up to use, without requiring constant maintenance to prevent it from turning into a rutted-out mess that gets worse and worse every year.
The runoff issue
Most of these terms have to do with limiting water flow on trails. When combined with gravity, flowing water is the enemy of sustainable trails. The out slope of a trail is the angle at which the tread is canted downslope, so that water sheets off the trail. The critical edge is the downslope edge of the trail where water can flow off. Lips and dishing are not what you want on a critical edge.
It all comes down to topography, the type of soil where the trail is built what the local precipitation is like. For the most part, Summit County, with its organic and glacial cobble soils and high precipitation, doesn’t lend itself to steep trails. Some of the old mining roads that are really steep are several feet or more below the surrounding grade — tons and tons of soil has washed down the slope. If you ride up Gold Run Road, you’ll pass several old, bandit DH trails, and you can see mini alluvial fans where the soil has washed down the trail and deposited on the road.
Boulders and check steps
We can have steep trails, though. It just takes extra thought and extra labor. One way to stop (or at least slow down) water on a trail is referred to as “check steps.” These can be made out of wood or rock or both (rock is almost always better, but it’s not always available). You’ve seen check steps on some of the steeper parts of the Colorado Trail and on the Soda Creek trails.
Basically, a check step is a dam that slows water as it flows down a trail. It’s more a reactionary measure — one that’s put in place on sections where, for whatever reason, you can’t or don’t want to re-route a trail that has growing ruts.
The Summit Fat Tire Society has found that as bikes roll over steps, people tend to hit their brakes, which causes a momentary lock up of the rear brake. This causes the downhill side of the step to gradually erode away. What we’re trying now is to place rocks on the downhill side of the steps to stop the erosion. It’s not always easy — you need to be able to find rocks big enough, and sometimes the local geology doesn’t cooperate. (You’d think this wouldn’t be an issue, since we’re in the Rocky Mountains and all, but in some places, it is.)
If you have a lot of big, honkin’ rocks in the area, you can armor the trail with rock, even get creative and build features that make the trail more technically challenging. But, as anyone who has used a multi-person rock cradle can tell you, moving and placing those big rocks is not only a lot of backbreaking work, it’s also slow going. And rock isn’t just for steep trails, either. It is the best way to deal with perpetually damp areas.
Making the grade
Of course, what’s best for a steep trail from a sustainability point of view is to lay the singletrack over exposed bedrock, like what they have in canyon country and parts of the Front Range. Exposed bedrock farts in the general direction of anything even the raddest, baddest bicycle can throw at it. Alas, there’s not a lot of it in Summit.
So that is why most of the trail construction in Summit generally doesn’t exceed grades of over 10-percent, except over short distances. It’s easier to shunt water off trails like this, as they tend see less skidding and less brake hopping, which leads to brake bumps.
A less-steep trail isn’t technically straightforward. They can have plenty of roots and rocks to work your arms and suspension, and, as much as I love to go fast (my old motorhead days, I guess), from a trail builder point of view, there are good reasons to design a trail that limits speed. It cuts back on brake bumps and user conflicts, and it usually means you’re less likely to blow out of turns and widen the trail. (Contrary to popular belief, whether or not we hurt ourselves is fairly low on the priority list.)
Some folks complain that less-steep trails are “boring,” given the state of bicycles today. Anyone with a few thousand bucks (or just available credit) can get a bike that’s capable of dropping the drops and rockin’ the rocks with ease. Fair enough.
But, if you picked up where I’ve been going with this, there is a reason trails are designed and built the way they are. A lot of it comes down to resources, both material and manpower. The more people who are willing to give just one day a season to trail work, the more creative our trails will be.
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