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  1. #1
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    From pump to jump: evolution ideas

    So we built it, and step 1 rides pretty well, though some larger features would really speed it up. It's a shared BMX race practice/pump track for my kids (boy-2.5 and girl-6) and their biker friends and then me and mine, with all different abilities so everything has to be rollable. The two doubles that exist, though small, are jumpable and manual-able (the doubles aren't in the picture, but the better one starts the line along the river, just off the bottom of the slide).

    From pump to jump: evolution ideas-photo-2.jpg

    The question now is how to evolve it, in other words where might the next "bigger" features go? I was thinking more of the same, but larger-removing every other single pump bump and putting in a double. Or are smaller step ups a good idea?

    Also, any tips on packing down triple-duty berm/jump/roll-in/transfers? As soon as they start to dry they really seem to want to crumble and on my daughter's and son's mini and micro bikes, those tiny tires really like to wash out over them. The offending lip is at about 4:00 in this picture. It is part of the bigger roll-in, but also a berm for the medium loop, AND a transfer into the smaller "back" section.

    Most of the features on the track are made of grade "c" stone dust that was donated by a neighbor... and I can't wait for the next batch, but I've still got enough to build a little bit, especially if I excavate a bit of the topsoil.

    Thanks!

  2. #2
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    I don't seem to be able to blow up the picture enough to see exactly what is going on with the dirt. You said it's "stone dust" ?! ?

    Most people build tracks with existing dirt (that would be in a regular backyard or woods--typically a loamy soil with some clay content). Baseball pitcher's mound dirt is known to be good as well.

  3. #3
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    I can't say enough good things about the material for building and surfacing. If I didn't think I'd be getting more for free whenever he's got it, I would have saved it for the top layer.

    It has weathered some pretty tough rain storms so far and has required very little upkeep. As it packs down, it is very tough, especially after raking out the stones after the first couple "drys." A finer dust would be smoother than a street, I think.

    I'm making a step up and will be adding to the height of the berms first. It's been fun to try and figure it out, but man, I really want this thing to fly! And now! Ha.

  4. #4
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    question... where do you get "grade "c" stone dust" and what stone is it? I've heard of BMX tracks using limestone tillings or limestone dust to coat their tracks... you see it on a lot of out door BMX tracks built by Elite Trax... is this the same stuff you are referring too?

  5. #5
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    Quote Originally Posted by mvwmvw View Post
    I can't say enough good things about the material for building and surfacing. If I didn't think I'd be getting more for free whenever he's got it, I would have saved it for the top layer.

    It has weathered some pretty tough rain storms so far and has required very little upkeep. As it packs down, it is very tough, especially after raking out the stones after the first couple "drys." A finer dust would be smoother than a street, I think.

    I'm making a step up and will be adding to the height of the berms first. It's been fun to try and figure it out, but man, I really want this thing to fly! And now! Ha.
    Can you post more pics ?

    For a small/tight track to be really fast, berms must be steep-faced (especially when they're more than 90 degree turns).

    Check out Zach Dank's backyard pics (from several years ago). There's a video out there somewhere also.
    Winter Digging | Dirt



    If you can get your berms like this, you'll be doing great.... ; )


    Tight 180. Sideways.
    Lee Likes Bikes


    You can also build your berms way up, so that the riding line swoops from low to high to low. The added elevation of your bike will generate more speed.


    Another great example from Lee McCormack of a short steep-faced berm for railing.


    http://www.leelikesbikes.com/jakarta...per-berms.html

  6. #6
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    Quote Originally Posted by cglasford View Post
    question... where do you get "grade "c" stone dust" and what stone is it? I've heard of BMX tracks using limestone tillings or limestone dust to coat their tracks... you see it on a lot of out door BMX tracks built by Elite Trax... is this the same stuff you are referring too?
    Hey I think that's right. Around here, limestone is crushed and used as road base. If you ever watch a road being built you'll see them do a layer of it, wet it, let it set, then compact it with huge rollers. The end result is almost like concrete by itself; then layers of asphalt go on top.

    Crushed Edwards Limestone Road Base - Wikipedia, the free encyclopedia
    We built some rollers with some of this limestone road base donated from a road project and it really did pack down and become ridiculously durable. I haven't worked with it enough though to know the ins and outs. We may have just gotten lucky with that particular mix.

  7. #7
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    as you can see here the entire track is built of clay fill (clay loam or silt) and then topped with a few inches of lime dustFrom pump to jump: evolution ideas-rock-1.jpgFrom pump to jump: evolution ideas-rock-2.jpg

    never heard of people building it entirely out of it...

    we use it to mix with expansive clay and it makes it less expansive so you don't get as much heaving and moving with the conditions

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