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  1. #1
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    ideal trail grade for long climbs

    what is the best grade/slope for a trail that climbs 2000+ feet.

  2. #2
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    Quote Originally Posted by jido
    what is the best grade/slope for a trail that climbs 2000+ feet.
    Anywhere from 1 to 10%
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  3. #3
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    add bunches of grade reversals

    check out the imba.com site and trail building resources. Very simply put, rule of thumb is trail slope should not to exceed half the grade.

    If you run into very short sections where it is steeper it can be ok, depending on soil. Also add many, many grade reversals. Have sections of short flat trail. Design the route so the water gets off the trail quickly and in many spots.

  4. #4
    featherweight clydesdale
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    Quote Originally Posted by jido
    what is the best grade/slope for a trail that climbs 2000+ feet.
    What cjohnson says

    Quote Originally Posted by cjohnson
    check out the imba.com site and trail building resources. Very simply put, rule of thumb is trail slope should not to exceed half the grade.

    If you run into very short sections where it is steeper it can be ok, depending on soil. Also add many, many grade reversals. Have sections of short flat trail. Design the route so the water gets off the trail quickly and in many spots.
    except that you should have short sections of DOWNHILL trail (assuming you're going up, not down), not short flat. A.k.a short sections of uphill if you start building from the top, which I find easier. Engineer those reversals into the design, it's better than building grade dips after the fact.

    Also, just because you have a 50% side slope doesn't mean a 25% trail grade works (it will on solid rock). You're governed by the 1/2 rule (half slope of the grade) until you start getting into 20%+ slopes. Then you have to start thinking about the "10% rule". This is why Smily said 1 to 10%, but the reality is that short of sand based soil, you can push short sections ( 10-40yards?) of up to 15% max slope, followed by a negative 2-3% grade reversal (short downhill) followed by another 12-15% upslope. A 12% max trailsection on 24% sideslope, 15% on 30% sideslope etc will keep you in check with the half rule.

    Once you're on a 30%+ hillside, you have the 1/2 rule covered everywhere, so the primary focus becomes the 10% rule. The 10% rule is the "average" slope over a longer trail segment that incorporates several reversals. So on the 30%+ slopes if you want a more challenging trail, you'd have 15% climbs with more frequent grade changes, that still averages out to 10% over a 100 or 200 yard trail segment.

    Also remember that part of your layout and whether you have an 8% or 10% average slope will likely be determined by "control points" (views you want to see, big rocks to go around) that should be identified as you scout the trail.

  5. #5
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    My general experience has been that on grades above 7% it becomes harder and harder to design in grade reversals. The downhill section just becomes too steep and the reversals get shorter and shorter. The grade reversals are critical to keep water from running down the trail and creating a ditch. If you mix it up a lot with grade reversals, short steep sections and short flat sections, the climb will be less boring and therefore seem shorter.

  6. #6
    featherweight clydesdale
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    Quote Originally Posted by bweide
    My general experience has been that on grades above 7% it becomes harder and harder to design in grade reversals. The downhill section just becomes too steep and the reversals get shorter and shorter.
    True, at 10% average grade and limiting yourself to 15% max for short sections, your basically going down, grade reversal (which if made right, can put some air under your tires), down, grade reversal, down. There isn't room for long flats leading to a grade reversal. Each reversal is noticeable. I guess this goes to what a builder wants out of a trail. 2,000 feet, I'd like a little of everything, to break it up. I've been doing a lot of building in an area with only 100' of topo change. I've been trying to make it as difficult as possible by pegging the climbs right at 10% average slope.


    Quote Originally Posted by bweide
    If you mix it up a lot with grade reversals, short steep sections and short flat sections, the climb will be less boring and therefore seem shorter.
    Just remember that water sits still on flat sections and will try to find somewhere to go. I imagine you're building with 5% outslope to shed water, but through wear and compaction, outslope is frequently defeated. Your flat gets a little berm along the edge and suddenly you have a mud hole that needs constant maintenance or a "knick". Or you wear a groove in the middle that just channels water from your flat to your next downhill without shedding it off the trail. You could create the appearance and feel of a flat, but provide a water shedding reversal if you just design your "flat" as an extended reversal with only 1% or 2% of grade. If the flat gets too extended you should it break into several smaller drainages by going something like +2%, -2%, +2%, - 2%.

    At 2% you can break each little slope section into lengths of roughly 75 to 150 feet depending on your soil. The trail sections between reversals need to get shorter as slope increases. You might only be able to push an 8% section of grade for 25 to 70 feet. Want a 15% section, make it short, only 5 to 25 feet and don't think about it in sandy soil. IMBA's Trail Building Book is an excellent resource. Parker's "Natural Surface Trails by Design" goes a step further with the soil analysis and what you can expect on various soil types.

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