The Subaru/IMBA Trail Care Crews are sometimes accused of sanitizing trails. This is heard most often when an eroded gully is replaced with a sustainable contour trail. But if the plan calls for a challenging trail, the crew will build it burly and difficult to navigate. If the new path must be ridable and walkable by everybody (including horses), then that's the specification followed.
IMBA crews have built several re-routes that are more sustainable and more difficult to navigate than the problem sections. In each instance, the locations were appropriate for technical features. Ideal spots for tough sections are rural regions or remote parts of large, diverse trail systems. Urban areas with a large trail-user population generally aren't the best place for aggressive trails. But there may be room for a challenging trail or two when urban green space is large enough to support a more extensive trail system.
In planning, think about all the people who will support and use the trail system. Don't build a public system that will appeal to only a small percentage of potential users. Instead, build a diverse system that spans a variety of desires and abilities.
A "stacked loop" system covers most bases. It typically includes:
A core or trunk trail. This begins at the trailhead, usually right off the parking area. It can be a loop. It's heavily used because it connects to the rest of the trail system. A core trail tends to be wider, smoother and have longer sight lines than other trails. It may need to be designed to ADA (Americans with Disabilities Act) specifications. It's often short (half mile or less) and non-challenging, allowing leisurely strolling side by side or family cycling. It doesn't provide as much solitude or exertion as other sections.
Primary trails. These comprise much of the loop system, forming circuits that don't require use of challenging trails. Primary trails add some excitement, though. Compared to a core trail, they typically have a narrower, rougher tread with more elevation changes and tighter turns. A few challenging features may be appropriate.
Challenging trails. The best location is at the back of a stacked loop system, or in a trail system that's more than an hour's drive from a metro area. The remoteness and rugged tread deters some users while providing a high-quality experience for others. Challenging trails give runners, avid cyclists and other enthusiasts a greater chance to find solitude as well as a way to test their skill and stamina.
One attraction of outdoor recreation is using physical talent to overcome adversity while enjoying natural surroundings. People don't walk the Appalachian Trail because it's easy. Pushing limits and reaching goals has been part of American outdoor recreation since the days of Roosevelt and Leopold. We can grow our constituency by building diverse trail systems that satisfy newcomers as well as backcountry veterans.
As mountain bikers become more skilled and equipment improves, they seek difficult trails to test their skill. For many riders, difficult means steep. But as we've seen, steep trails can create big erosion problems. We don't want people locking their brakes and taking the trail with them. To preserve the land and ensure future trail access for cyclists, new trails must be routed gradually across the slope and generally avoid the fall line. Some mountain bikers may consider these contour trails too tame, so the design can add elements that enhance technical challenge while not reducing sustainability. Rock is effective because it "hardens" a trail as it increases difficulty.
Here are five ways to use rock in trail design:
Steeps. Locate solid rock slabs or faces where a trail can run straight down the fall line without causing erosion. San Antonio riders are challenged by The Wall - a 15-foot-high rock face that falls away at a 90-percent grade. It's a favorite challenge for local riders yet remains erosion free. When designing a feature like this into a trail, open the outrun to prevent heavy braking, or floor it with rock. Use a natural grade reversal or dip above the steep to keep water off the trail.
Rock gardens. Route your trail over and through rocky areas. West Virginia's Tea Creek Mountain Trail has a rock garden that everyone tries to clean but rarely does. This rubbly section batters bikes and appeals to hikers and equestrians, too. People expect rocks in nature and won't avoid them if they seem natural. The key is that no matter how difficult a rock section might be, it still must be the easiest route. This gives people no choice but to stay on the trail, preventing trail widening or shortcuts.
Rock chokes. A series of boulders staggered on either side of the trail makes a narrow choke or slot that enhances the challenge. It also reduces cycling speed. Be sure this narrowing blends naturally with the trail. Otherwise, people will find it annoying instead of interesting, and may create a new route around it.
Armoring. Use large rocks to "pave" a trail and prevent erosion. Trailbuilders in soggy Wales are forced to armor entire pathways to escape year-round mud. Large, ominous rocks are buried in the tread, making the trail interesting and dry. When armoring, use boulders that take two or three people to move. This ensures that the rock will stay in place. Bury at least a third of each rock, taking care to make the section look natural. Experiment with different placements to mimic natural outcroppings.
Drop-offs. Incorporate natural ledges or use rock to build short drop-offs. This addition on a contour trail challenges cyclists ascending or descending. Six to 12 inches is the right height for most riders. Be sure drop-offs fit the overall flow of the trail. Put them in a bike-length series where riders won't be taken by surprise. This spacing makes it possible to climb as well as descend. Transitions are important. A tight turn following a drop-off will cause cyclists to skid or ride off the trail. Tall drops can offer two lines - one difficult and one easier using a ramp or chock stone.
Build narrow trails with exposure and you're guaranteed to raise the technical ante. Exposure is empty space beside the trail tread. It adds challenge while retaining sustainability. Riding singletrack across a steep hillside with nothing but air on one side always produces grins - and a shot of adrenaline in even the most experienced rider. We've ridden bench-cut trails on slopes that exceed 45 percent. The exposure on such trails provides a psychological challenge, too. A three-inch rock seems like a boulder when a 50-foot drop looms on your side!
Adding exposure is even more effective in areas where it's uncommon or unexpected. You don't need mountains. Seek features such as rock outcroppings, small embankments or any elevation change. A trail across a slope will seem more challenging with a rock or thorny bush on the uphill side, forcing cyclists to tightrope along the downhill edge.
Examples of great trails with significant exposure include Bootleg Canyon, NV; Portal Trail, Moab, UT; Shenandoah Mountain Trail, VA; Tea Creek Mountain, WV; and many trails in Fruita, CO.
Fallen trees. Leave them on the trail, but not all the way across. Some trail users like logs for the test they present. Others will avoid them by going around, even if it means leaving the trail. A well-designed trail accommodates everyone, which means no major obstructions. Leave a log covering only part of the trail, allowing an unblocked route to one side. This gives users the option of scaling the log or skirting it. (This won't work on tight singletrack, however). Make sure there are good sight lines in both directions and that the direct line is over the log. Try to keep the trail narrow. Don't use logs as a way to make cyclists slow down. In fact, they may ride faster in order to jump them.
Log ramps. A popular maintenance technique is using small logs to create ramps before and after big logs. This is generally a bad idea. Most trails are shared use, and these log piles are a big obstacle to horses and hikers. One solution is to cut a gap and make the ramp optional. However, we've seen hundreds of ramps and only three or four were well constructed. Throwing a bunch of rotting logs and branches at an obstructing log and calling it trail maintenance is just being lazy. A well-built ramp uses logs at least 8-10 inches in diameter. If they need to be fastened, use rope or wire, not dangerous spikes. Should you decide to make a ramp, build it well and take pride in your work. Always create an easier option, too.
Log chokes. Conflicts between mountain bikers and other trail users often result from the faster speed bikes travel. Just like traffic calming devices on roads, the best way to slow cyclists is by narrowing the tread, creating tight spots and adding curves. Make a log choke by staggering logs on either side of the trail. Be sure this narrowing flows naturally with the trail. Otherwise, cyclists and other users may avoid it by creating a route around it.
Balance beams. A log placed lengthwise next to the trail will be used as a fun and challenging balance beam by people on foot and bikes. It's also a handy place to rest. Place these logs upslope of the trail where they won't impede drainage. Set them into the ground so they don't roll.
Log steps. Use large logs to make short steps or drop-offs. This is a good way to challenge cyclists in an area without natural difficulties. A drop of 6-12 inches is right for most users. Make sure steps fit with the trail's flow. Use them in a bike-length series where riders won't be taken by surprise. Transitions are important - a tight turn following a step is awkward. Also, be sure to account for water flow.
First, a reminder: Put trails on side slopes whenever possible. Avoid flat areas because water or sand may accumulate. Flood plains, river bottoms, plateaus, meadows, old roads - trails in these places can turn into mud bogs or sand traps that require continual maintenance. On the other hand, contour trails along side slopes provide good drainage. They are far more appealing and will pass the test of time. Here's how to add spice to contour trails by using ups and downs.
Grade reversals. On sideslope traverses, make the route more interesting by "surfing" the contour lines. Create a rolling trail that dips and rises frequently. Reverse the grade subtly every 20-40 feet. Visualize rhythmically spaced "waves." Remember that the trail grade must always remain less than half the sideslope at 40 percent, no part of the trail should exceed 20 percent, and we recommend 10 percent as a maximum overall grade. Route the trail on the uphill side of trees to use bench and avoid roots. Surf around natural obstacles. Grade reversals make a trail fun and improve drainage.
Grade breaks. Lack of grade changes is a common trail design error. Long runs of constant grade encourage excessive speed (if downhill) and they're boring (if uphill). Erosion will be a problem if water focuses down the path. For these reasons, interrupt grades with breaks where possible. Short descents mixed into long climbs help users regain momentum and catch their breath. On downhills, short climbing interludes provide variety, challenge and let cyclists get off their brakes. Grade breaks also ensure that water doesn't gain speed and erode the trail.
Constant ups and downs. If your local terrain is generally flat, it's even more important to use short ups and downs to challenge cyclists. Make use of every available change in terrain. The 1996 Olympic mountain bike course in Conyers, Georgia, is a good example. It's always undulating. Despite the lack of big hills, the course is very challenging because racers never get a chance to rest.
Gravity drops. The goal is to create a large dip in the trail with an equal fall and rise. Cyclists drop in and their momentum shoots them up the opposite side. G drops are one place where the trail grade can be a bit steeper than we recommend. The key is a smooth transition and clear sight line. If the drop is designed correctly, the average rider won't need to brake. That's important so dirt won't be pulled down. G drops shouldn't be used on trails that have lots of hiker or horse traffic. These users tend to scrape a downhill grade, increasing erosion. Good sight lines are key. Cyclists must be able to see the entire drop from either side. Remember to keep the trail grade under half the sideslope grade, and limit steep sections to 15-30 feet.
A clinometer is also known as an inclinometer or "clino." It's a hand-held instrument that tells the slope of a hillside or grade of a trail, making it an essential tool for building sustainable trails.
On level ground, stand about 20 feet from your partner and hold the clino to one eye while closing the other.
You'll see a line and a rotating scale of numbers. Tilt the clino up or down until the zeros align with the line. Now open your other eye and extend the (imaginary) line onto your partner. The point where the line falls on your partner is the "zero point."
To measure or "shoot" the average grade of a hill, fall line, sideslope or tread grade, have your partner stand directly uphill from you. Hold the clino to your eye, keep the other eye open, and set the line onto your partner's zero point. This time, instead of zeros, there will be a number behind the line. This is the grade of the slope you're standing on. Most clinos have two scales: degrees and percent. Always use percent.
It doesn't matter exactly how far away your partner is. What is important is that both of you are standing on the same slope. If the slope changes in between, you'll get an average of the two slopes. For example, if you stand across a gully from each other, it would be possible to shoot a 0 percent grade. You need to measure the two grades independently.
The best trail systems strike a balance between protecting resources and providing recreation. A well-designed contour trail system takes people into nature while safeguarding the environment. Techniques for design, construction and maintenance constantly evolve, but the goal is always the same: Build trails that are sustainable and appealing.