Take a Bike! And Feel the Flow

Berms at Burke Mountain, Vermont. Photo by Dale and Darcy Cahill.

While the difference between a deer trail and a hiking trail may be obvious, what makes a trail good for feet is not always what makes a trail great for tires. Whereas hikers (and deer) tend to be destination oriented, mountain bikers look for trails that allow them to experience the woods above, around, and below them.

Hardy Avery of Sustainable Trailworks in Morrisville, Vermont, has been building mountain bike trails for much of his life. When hired to design and build a trail, Avery begins by talking to the landowner about management plans they may already have in place. This collaboration is key to planning and designing a trail that respects other land users, protects vulnerable ecosystems, and (when on public land) follows guidelines set by the Agency of Natural Resources.

The next step is to assess the terrain. During this stage, Avery gathers information about soil types, drainage, and slope, and then begins to conceptualize possible routes. He decides where and how to bridge wet spots and streams and how to connect various high spots along the route. At just about every step, Avery uses a clinometer – the goal is to keep the slope under 10 percent. This information is essential in designing a trail that flows across the terrain.

As Avery gets to know the woods he’s working in, he determines where the control points are, both negative and positive. Negative control points are things he wants his riders to avoid, like swamps and cliffs, and positive control points are the naturally beautiful features – like vistas or waterfalls – that he wants his riders to see. GPS coordinates are taken and a map begins to emerge. At this point, Avery begins to hang flags at eye level along the envisioned trail corridor, looking both forward and backward and constantly checking his clinometer. The speed of the rider is of constant concern. A seasoned mountain bike rider himself, Avery knows that riders like rolling terrain and kinesthetic diversity. Once he rough flags the route, he can estimate the cost of the proposed trail (on average about $5 a foot). Once the trail builder and the landowner agree on the price, wire-pin flags are placed in the ground and the building can begin.

Trail builders rely on a variety of tools to construct trails, including a McCloud (a flat, square shaped blade with a cutting edge on one side and a rake on the other that’s used to remove berm) and a Pulaski (half axe, half hoe). Trail builders also use a sledge hammer, wheelbarrow, and basic landscaping tools like pruners and rock bars. On larger jobs, Avery uses a 1.5-ton mini-excavator. When natural building materials are unavailable, he has to carry in drainage stone and lumber. There are two hard and fast rules for trail building: never fill without retaining, and always channel water off the surface of the trail. Retaining walls are used to support turning platforms on switchbacks and to shore up trail edges. Trail builders prefer to make these walls with large rocks, as they don’t rot and their weight provides strength in the wall. The top of a retaining wall must be lower than the trail tread so that water will sheet across rather than gather on the trail. Strategically placed grade reversals, “nicks” (shaved down sections of a trail that are canted to the outside) and rolling grade dips all help to shed water from the trail. Good signage is essential to keep riders on the trail. If riders cut corners, they can slowly widen trails and make them vulnerable to water erosion.

For mountain bikers, flow is everything. A good trail hangs together as a well-connected whole, with perfectly placed corners, well balanced ascents and descents, and an overall unity that helps to pull the rider along. On a well-built trail, riders can relax and fully immerse themselves in the experience of mountain biking. In the end, a memorable mountain bike trail is a work of art.

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