1. The Half Rule
2. The 10-Percent Average Guideline
3. Maximum Sustainable Grade
4. Grade Reversals
5. Outslope

1. Avoid the Fall Line Fall-line trails usually follow the shortest route down a hill - the same path that water flows. The problem with fall-line trails is that they focus water down their length. The speeding water strips the trail of soil, exposing roots, creating gullies, and scarring the environment.
2. Avoid Flat Areas Flat terrain lures many trailbuilders with the initial ease of trail construction. However, if a trail is not located on a slope, there is the potential for the trail to become a collection basin for water. The trail tread must always be slightly higher than the ground on at least one side of it so that water can drain properly.

1. Do everything you can to keep the water off the tread, and users on it
2. Build on the contour and use frequent grade reversals - surf the hillside
3. Follow the half-rule: A trail's grade shouldn't exceed half the grade of the sideslope
4. Maximum grade should be 15 percent (except for natural or built rock structures)
5. Average grade should stay under 10 percent (with grade reversals)
6. Route trails to positive control points (viewpoints, water, other attractions)
7. Use bench-cut construction, and excavate soil from the hillside
8. For reroutes, reclaim old trail thoroughly - the visual corridor as well as the trail tread
9. For highly technical trails where grade will sometimes exceed 15 percent, use natural rock, rock armoring or other rock features to add challenge and improve sustainability.

1. Not Getting Land Manager Approval We know, we know: you just want to build trails. But believe us when we tell you that nothing - not a single darned thing - more important before starting trailwork than the approval of the land owner or manager. In our experience, a failure to secure permission is the single biggest cause of trail closures. When it comes to building trails, to ask for forgiveness is not better than to ask for permission.
2. Falling for the Fall Line Put simply, fall line trails are erosion nightmares. They turbo-charge natural and user-created erosion, exposing rocks and roots and generally living short lives before becoming loose, wide, ecosystem-damaging disasters. To build trails that last, use the Half Rule: trail grade, or steepness, shouldn't exceed half the grade, or steepness, of the hillside; and the 10 Percent Rule: overall trail grade should be 10 percent or less.
3. Guessing the Grade Nobody, no matter how masterful their eye, can guess trail grades right every time. Trust us, we know. Sure, it's fun to try, but use a clinometer to confirm the grade whenever you're laying out trail - it's worth a regiment of self-powered, Fantasia-style Pulaskis, because no amount of trailwork can fix a trail built on an unsustainable grade. If you don't have a clinometer, we highly recommend an investment in this indispensable tool.
4. Going Against the Flow Not even race courses - which are sometimes designed with erratic flow to throw off a racer's rhythm - should make this trailbuilding faux pas. All trailbuilders should make "smooth transitions" their mantra. Bad flow, especially fast sections leading into sharp turns, is a primary cause of user conflict. When you are building, think flow - it's the key to an enjoyable trail.
5. Half Bench is Half Baked The only time you should ever skimp on a fully bench cut trail is (1) when the sideslope is so steep - 80 percent or greater - that the backslope exceeds six feet in height, or (2) when your trail design forces you to build close to the downhill side of a large tree. In both cases, a proper crib wall should be built to support your partial bench, and, as in all trails, the tread should maintain a five to seven percent outslope.
6. The West Virginia Climbing Turn Our friends in West Virginia affectionately gave this name to some of their steep, fall line turns, and while they've gotten away with it in a few locations because of the soil and user types, most fall line turns will erode badly. If you want your climbing turns to endure, build them on sideslopes with no steeper than a seven to 10 percent grade.
7. Building Houses of Straw Remember the little piggy who built his house with straw? He got chowed by a wolf. Using shoddy materials when building trail structures leaves you and others similarly vulnerable by reducing the structure's safety and longevity. This opens the door to things like pain, guilt and even lawyers. Build it right. Keep the wolves at bay.
8. Finishing a Line Before Its Time We heartily support on-the-trail training, but some new trailbuilders are so eager to keep building more! new! better! trails that they don't devote enough time or care to each new trail section. Resist the temptation to move forward. Don't finish a line before its time, and always patch past mistakes.
9. Building a Pathway to Grandma's House This is what we call some trailbuilders' obsession with lining trail with logs. A properly constructed trail shouldn't need them. In fact, lining a trail with logs can trap water and increase erosion.
10. Ignoring Old Wounds As mountain bikers we may think our scars are cool, but scars on the land left by closed trails are damaging wounds that need to heal. Always reclaim eroded areas with check dams - natural obstacles like logs or rocks that divert the flow of water and soil - and reclaim all closed trails with transplanted native vegetation that conceals the old corridor. Shine the spotlight on the great trails you've built, not the ugly scars that have been left behind.

 

Rock Armoring

(Reprinted with permission from the IMBA. More information can be found on the IMBA's website for Trailbuilding Resources.)

Nine Tips That Apply To All Armoring Techniques

1. Start at the Bottom. If you're working on a slope, start at the bottom and work upslope. The weight of the rocks will hold your work together.

2. Drop the Anchor. The first "keystone" in an armored trail section plays a crucial role in anchoring everything in place. The anchor rock must be large and immobile once set in place with at least two-thirds buried. Remember that angular rocks are better than round. Place a solid anchor every couple yards.

3. Laying the Tread. Once the anchor is solid, follow by placing more rocks to form the trail tread. Ensure all rocks touch one another and everything is locked in place. Like building a puzzle, you may need to move rocks around to find the best fit. If a rock wobbles under foot, reposition it. Use smaller angular rocks as wedges to fill gaps. Without mortar, friction and gravity must hold the rocks together.

4. Break the Joints. Place each rock so that it spans the gap between the adjacent rocks. Like building a brick wall, you must avoid directly aligning joints because they will weaken the structure. Each course of stone should overlap the cracks in the preceding row. Try to minimize lengthwise gaps that run parallel to the trail that might catch a bicycle wheel.

5. Use Tie Stones. Every four to six feet, place a larger stone that will span most or all of the trail tread. Like the anchor, a tie-stone helps lock everything together.

6. Fill the Gaps. One of the most important steps is to fill the gaps with small rocks, stone dust, gravel or sand. Pack the fill in tightly using hand tools. "Inch-to-dust" is a term used to describe small quarry waste, also known as "crusher fines." This broken stone is the best fill material because it contains natural cements present in the parent stone. Scottish trailbuilders call it "magic dust."

7. Compact. It is best to compact any surfacing material in layers while slightly wet. A mechanical compactor is the best tool for this key step.

8. Corral the Trail. Include something to define the sides of the armoring. Large ominous "gargoyle" rocks, logs, trees or other obstacles staggered on either side of the trail serve as physical and visual barriers to keep riders on the armored section of trail. Make sure the narrowing and the rocks flow naturally with the trail. Otherwise people will find it annoying instead of interesting, and may create a new route around it.

9. Consider Trail Flow. Smooth flow is vital on trails for cyclists. Mountain bikers love the rhythm of a trail where one turn blends into the next, and the trail surface is somewhat predictable. A trail with good flow helps minimize erosion, user conflict, and safety concerns. Strive for a subtle transition into the armored section.

 

Using Logs

(Reprinted with permission from the IMBA. More information can be found on the IMBA's website for Trailbuilding Resources.)

Leave fallen logs on the trail. Some trail users view a fallen tree as a welcome challenge. Others see it as an insurmountable barrier and will go around, even if this requires leaving the trail. A shared trail must accommodate everyone and should offer a route without obstructions. The solution is to leave the log covering only part of the trail, allowing an unobstructed route to one side. This provides the option of passing over the log or skirting it (This will not work on narrow singletrack, however). Make sure there are good sight lines in both directions and that the route over the log is the more direct line. Try to keep the trail narrow. Don't use fallen logs to slow riders down. In fact, logs across the path may encourage cyclists to ride faster to jump them.

When is a log too large to be ridden? We've seen riders give trail workers grief for removing 3-foot high logs, so almost any size log can be in play. However, we've also seen erosion and multiple paths develop around the end of deadfall that obstructed the trail. One trailbuilding goal is to minimize our impact on the landscape. If fallen logs divert riders off the established tread, our impact increases.

Log ramps. A popular but misguided trail maintenance technique is to build a pile of logs to create a ramp up and over an existing fallen log. Our opinion is that these log piles are generally a bad idea. Most trails are shared use, and these flimsy ramps are a big obstacle to horses and hikers. One solution is to cut a gap and make the log pile optional. However, we've only seen three or four log piles out of hundreds that were well constructed. Throwing a bunch of rotting logs and twigs at an obstructing log and calling it trail maintenance is just being lazy. A well built log ramp will use at least 8-10-inch diameter logs. They may need to be fastened in place: use rope or wire, not dangerous spikes. Build them well, take pride in your work, and be sure to leave an easier option.

Log chokes. A series of logs staggered on either side of the trail can provide a narrow choke that enhances the ride. This strategy can slow users and add challenge. Make sure the narrowing flows naturally with the trail - otherwise people will find it annoying instead of interesting, and they may create a new route around it. Conflicts between mountain bikers and other trail users often are a result of the faster speeds that bikes travel. Just like traffic calming devices on roads, the best way we've found to slow cyclists is by narrowing the tread, creating tight points, and adding curves.

Balance beams. Logs placed lengthwise next to the trail can also provide a unique challenge. For some users the log will function as a balance beam, while others will use it as a bench to rest on. It's important to set these logs into the ground so they don't roll and to place them upslope of the trail where they won't impede drainage.

Log steps. Use large logs to construct short steps or drop-offs. This addition can challenge riders in an area without natural terrain difficulties. A six-inch-to-a-foot drop is appropriate for most users. Make sure the step fits with the overall flow of the trail. Use them in bike-length series in an area where riders won't be taken by surprise. Transitions are important: a tight turn following a step is awkward. Be sure to account for water flow.

 

Building Ladder Bridges

(Reprinted with permission from the IMBA. More information can be found on the IMBA's website for Trailbuilding Resources.)

A ladder bridge is an elevated boardwalk put in place to get over and obsacle or wet area, or simply to add an interesting feature to the trail. Here are some basic tips to building ladder bridges from the IMBA.

1. Follow IMBA's Freeriding Guidelines These tips, in the freeriding section of IMBA's website, provide important information on risk management, design, materials and construction techniques for wooden structures. Before starting, make sure to get permission from the local land manager.

2. Locate the ladder bridge properly Ladder bridges can be added to trails of various difficulty level - just be sure that the challenge matches the skill of the expected riders. On beginner trails, ladder bridges should be wide and low to the ground. As skill levels increase, the structures can be higher, narrower and incorporate turns, camber changes and drop-offs.

On beginner trails, place the ladder bridge to the side for an optional, more challenging route. On advanced trails, the feature may be located in the main line. However, a clearly visible option around the ladder bridge should always be incorporated into the design.

3. Elevate the ladder bridge The feature can be raised off the ground in various ways - but be sure to use a durable and sustainable method. Some techniques include large rocks, strong tree stumps that won't rot, well-designed wooden posts, or a log-cabin style crib. Never attach a ladder bridge to live trees and avoid using rot-prone or flimsy deadfall.

4. Armor the entrance and exit The trail surface at the entrance and exit of a ladder bridge will require additional hardening, especially on steeper grades and landing areas. Check the IMBA website for detailed armoring techniques.

5. Vary length, height and width to add appeal and challenge Part of the appeal of a ladder bridge is simply that it offers a different challenge and aesthetic than is found in the natural environment. A ladder bridge, by its design, is not necessarily challenging. The challenge comes from how high the bridge is off the ground, how long it is and how narrow the deck. Sometimes the mental challenge of balancing on a narrow bridge is greater than the physical risk.

6. Add turns and camber A great way to add challenge to a ladder bridge is to incorporate turns. The amount of deck space provided for the turn should be consistent with the style of trail and technical features nearby. On beginner and intermediate trails, the turning radius and deck must be wide. On advanced bridges it can be narrower. Changing the camber of a ladder bridge is another way to add challenge. Banked turns are great ways to add flow and fun.

7. Change the incline and decline Ladder bridges with sharp inclines that require pedaling, and declines that demand breaking can be very challenging. Again, the steepness should flow with the surrounding trail style.

8. Join ladder bridges together to create alternate lines Ladder bridges can be quite elaborate. Consider building alternate bridge lines that offer different levels of challenge. Offshoots can be narrower than the main bridge, provide separate exits or drop offs or include more turns.

9. Incorporate drop-offs Drop-offs from the end of the bridge to the ground or onto another bridge will add challenge. The height of the drop should match the challenge level of the trail. Make sure to consider the forces of a drop-off in the bridge and landing zone design.

10. Combine ladder bridges with other technical trail features Ladder bridges can be linked with teeter-totters, A-frames and other technical trail features to form a flowing series of challenges. Get creative!

Copyright 2008-2009. Site design by MTB Resource.