CouchingTiger
August 25th, 2003, 02:03 PM
I just wanted to start a thread about some best practices that we have been learning as we are able to build more freeride/DH type trails. This a new frontier not only to the folks at NEMBA but pretty much to everyone (save a few DH ski areas and a mess of rogue builders).
From my standpoint, the main concerns are reliability, maintainability and safety. To that end, many FR/DH trails as well as certain types of natural obstacles are really hard to maintain. The flow of traffic wants to naturally destroy them.
Right now I'll discuss a technique/device that I have found to be super useful in shoring up a dirt based roll-in drop-off. A roll-in drop-off is basically a steep drop (though typically not verticle) that you can either nose-down or you can roll-in with some speed and huck off.
The problem with these types of obstacles, especially when dirt based, is that erosion wants to wreck them. You are fighting not only wind/water wanting to smooth it out but also folks riding over it.
What I've noted good luck with is a man made, wooden frame that you sink into the run-in of the drop. This frame doesn't inhibit the natural flow of the drop at all but serves to shore up the end of the drop and hold the earth from eroding down the slope. It also cribs the back side of the drop while still allowing folks to nose-in on it vs. huck it.
The main construction is a frame based on two roughly parallel members of wood (I used PT landscape timbers in this example). These pieces (rails) would go parallel to the flow of the drop. The support comes from three timbers (rungs) cut to span between the two rails. The rungs are bolted to the bottoms of the two main rails, one on each end and one in the middle. you then have, basically, a ladder frame that should be the width of and a good part of the length of the "ramp" of your drop.
Affixing the ladder frame to the drop is simply a matter of burying it into the ramp so that the rungs are under the surface and only part of the rails are exposed. The end of the frame should not extend past the nose of the drop, though you can extend it a little and crib the frame up from underneath with rocks and dirt. The frame shoudl not be left overhanging at all though. It needs to be fully supported.
I just put one together that is going to get a trail up at Sunday River. This one is a little more elaborate as I wanted the make sure and crib the backside of the drop. We'll see how it works.
-Couch
From my standpoint, the main concerns are reliability, maintainability and safety. To that end, many FR/DH trails as well as certain types of natural obstacles are really hard to maintain. The flow of traffic wants to naturally destroy them.
Right now I'll discuss a technique/device that I have found to be super useful in shoring up a dirt based roll-in drop-off. A roll-in drop-off is basically a steep drop (though typically not verticle) that you can either nose-down or you can roll-in with some speed and huck off.
The problem with these types of obstacles, especially when dirt based, is that erosion wants to wreck them. You are fighting not only wind/water wanting to smooth it out but also folks riding over it.
What I've noted good luck with is a man made, wooden frame that you sink into the run-in of the drop. This frame doesn't inhibit the natural flow of the drop at all but serves to shore up the end of the drop and hold the earth from eroding down the slope. It also cribs the back side of the drop while still allowing folks to nose-in on it vs. huck it.
The main construction is a frame based on two roughly parallel members of wood (I used PT landscape timbers in this example). These pieces (rails) would go parallel to the flow of the drop. The support comes from three timbers (rungs) cut to span between the two rails. The rungs are bolted to the bottoms of the two main rails, one on each end and one in the middle. you then have, basically, a ladder frame that should be the width of and a good part of the length of the "ramp" of your drop.
Affixing the ladder frame to the drop is simply a matter of burying it into the ramp so that the rungs are under the surface and only part of the rails are exposed. The end of the frame should not extend past the nose of the drop, though you can extend it a little and crib the frame up from underneath with rocks and dirt. The frame shoudl not be left overhanging at all though. It needs to be fully supported.
I just put one together that is going to get a trail up at Sunday River. This one is a little more elaborate as I wanted the make sure and crib the backside of the drop. We'll see how it works.
-Couch