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  1. #1
    mtbr member
    Join Date
    Feb 2004

    Flow Trail Advice


    Does anyone have any general advice on designing flow trail, or know where I can get it? Through my club I have permission to build six miles of trail at a local state park. It's in a region that doesn't have a lot of flow trail and that is what I'd like to build. Just general info now- how to lay out a good flow turn, a nice speedy but sustainable trail, etc. I have the corridor flagged and now I need to start laying out trail. I'm familiar with IMBA trail design standards but I'd like advice on how to actually lay out flow trail.

    I try to avoid sexual innuendo, but its hard.

  2. #2
    Rider, Builder, Dreamer
    Reputation: sambs827's Avatar
    Join Date
    Dec 2008
    Some things that are on the top of my head, in no particular order:

    1. Grade reversals are your best friend.

    2. Keep the grade to a minimum. It's really easy to get too steep of a grade.

    3. It's totally okay to have to pedal a little bit to keep speed up.

    4. Give people a chance to slow down before turns. The faster you're going, the farther back you need to see the turn. Too much speed before the turn = braking bumps galore.

    5. Grade reversals are your best friend.

    6. It's okay to have a slight uphill stretch in the middle of a long descent.

    7. Make long legs. If you're making multiple traverses (switchbacks, climbing/descending turns, etc.) try to make the stretches in between as long as you can. Each 180 degree turn you do loses elevation that's difficult to make up.

    8. False flats are a wonderful thing.

    9. Design some sections so that the fastest people start noticing little doubles. They don't have to be tall. In fact, it's best if they're rather short (in height) and discreet; that way the average rider will just roll right over them.

    10. Grade Reversals are your best friend.

    11. Any time you're trying to switch direction, try to build the turn on a part of the hillside with a shallow slope. 180 degree turns on a steep sideslope are super hard to build properly and if not built properly are not much fun.

    12. Use gravity to slow riders down from a fast section, not turns. See 1,3,5,6.

    13. Grade reversals are still your best friend.

    14. Only one or two people should be responsible for the layout. If it's two people, they should work together and have a similar mindset. This ensures consistency from one end to another. These people should also lead digging efforts. This does NOT mean that other input shouldn't be considered.

    15. I'm sure some of the other guys here can give better advice.
    Go ride your bike.

  3. #3
    Reputation: Cotharyus's Avatar
    Join Date
    Jun 2012
    Wow, I'm not sure there's much to add to that. It's really good advice, and rather thorough. The only thing I would add to that is a safety point that I'm not sure can be stressed enough. Flow trails often become an "all about speed" thing, especially for advanced riders. Be certain your sight lines are open enough, and support your design. You don't want those little doubles in a place where someone realizes there's a slower rider right in front of them while they're in the air. So if you wanted to add number 16 to the above list:

    16. Be conscious of your sight lines, make certain they are appropriate.

  4. #4
    trail rat
    Reputation: slocaus's Avatar
    Join Date
    Jul 2005
    @sambs827 nailed it very well.

    Build and use a Flow Stick (R) an idea that Zachi Anderson of Forest Trails Alliance conceived. Use 2 inch PVC pipe in 20 foot lengths with swedged ends so you can attach them. Use 7 to 10 so you have 140 to 200 feet. Lay it out roughly, then push the ends toward the center and bounce the pipe, like the old rope snake trick making waves. It will lay our a smooth flow trail with no kinks and even radius turns. You can get even radius in the left to right turns as well as the rise and fall of the grade reversals.

    A quote from Drew P. "It seems they produce what would be called a "sine-generated curve" This is the same shape river meanders and bent spring steel (or pvc pipes?) form. The sine-generated curve has an interesting property in that the shape represents the most uniform distribution of change along a curve. A meandering river forms a sine-generated curve because it is the shape that allows the water to change direction using the minimum amount of energy. In the same way that shape allows the bicycle to change direction (both up/down and left/right) using the minimum amount of energy (which comes from shear forces applied to tires). It is the path that will turn a bicycle a certain angle over a certain distance using the minimal amount of energy which is then used to make the smile on your face bigger?"

    This is the only good photo I have using it, but look at Forest Trails Alliance on Facebook for more photos. I've included a couple photos of the result. This is a huge project in CA State Parks that will open in the spring of 2014.
    Attached Thumbnails Attached Thumbnails Flow Trail Advice-pb091944.jpg  

    Flow Trail Advice-p3042300.jpg  

    Flow Trail Advice-dsc00216.jpg  

    Flow Trail Advice-p2222035.jpg  

    "The physician heals, Nature makes well" - real fortune cookie

    CCCMB trail work for trail access - SLO, CA

  5. #5
    Join Date
    Apr 2012
    slocaus this is a great idea I think I am going to try this system out. Just seems to be a great way to visualize a unbuilt trail. Thanks for sharing!

  6. #6
    mtbr member
    Join Date
    Jun 2008
    wow. excellent thread and excellent layout tool. thanks!

  7. #7
    Delirious Tuck
    Reputation: thefriar's Avatar
    Join Date
    Jan 2008
    What sambs and slo have said.

    FC NEMBA has been doing a bunch of flow in our more recent builds, and the Red Trail at Wilton Woods is a great example of how to achieve that kind of trail in CT.

    Another one to slocus/Zacchi method thats easiest way to determine flow or no (forget sustainable for a blink) is: Run your trail sections, if you notice awkward speed or footing changes to turn or "dancing" through sections or stutter step, you have a flow killer. Tweak design (add a berm or grade reversal or lower the grade or increase radius).

    You can have flow through tech too. Most people think flow trails have to be absolutely smooth, if you run through a tech section (know your foot falls first!) and can keep your running momentum, you can have the same on a bike. Some riders will take longer than others to appreciate this concept (i.e. people who don't like speed), but when they do it will change their opinion.

    PM me if you want a local-ish set of eyes for flow, although you have Puke out there and he knows his stuff.

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