The age old question... How do you build a BIG double? (6/7/8-10 feet tall)

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The age old question... How do you build a BIG double? (6/7/8-10 feet tall)
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flag siderealwall2
Posted: Oct 1, 2014 at 21:40 Quote
So... We have a spot in our little town thats been getting 99.9% positive feedback from the community.
And I want a nice sized step-up with a good sized gap (think a bit shorter height than post office*) to ramp it up a bit.
I have an idea for the line, and dirt is not a problem. It is in an area with quite a few trees.
This is my first time building up anything of the height, and was wondering if anyone had pointers for my project.
Thanks! Smile

http://static.squarespace.com/static/522cca61e4b090a2d4816a05/53beea67e4b0fb102fa2d1f9/53beec73e4b01539a52ace18/1405021516353/Aptos%20Post%20Office%20Jumps.jpg?format=500w

(*the jump to the right of the wooden lip) (if you follow the "4" in "2014" on the watermark vertically, you should see it)
flag cmc4130
Posted: Oct 2, 2014 at 8:44 Quote
What I call the "pyramid method" of building jumps. Although some people pack the side and back almost vertically, this is not the most durable way to do things. In Mother Nature, all dirt wants to go "mountain shaped." Therefore the strongest structure is going to be much wider at the base than at the top.

I explained it over here:
https://www.pinkbike.com/forum/listcomments/?threadid=138473
and here:
http://forums.mtbr.com/trail-building-advocacy/i-kneed-ideas-my-new-trail-please-help-890432.html#post10869357

Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/Pyramid-Method-of-Building-Dirt-Jumps.jpg
Pic from Texas Toast jam in Austin, Texas. Once again, note how much wider the base of each jump is than the top.
Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/Texas_Toast_Dirt_In_Progress.jpg
Unsecure image, only https images allowed: http://www.lost-civilizations.net/images/mayan/uxmalpyramid.jpg
photo

Note how, even with filled in tabletops, the base is wider than the top, and the sides slant outwards.
Unsecure image, only https images allowed: http://i772.photobucket.com/albums/yy10/stickyfingaz/142.jpg
Cool
flag siderealwall2
Posted: Oct 2, 2014 at 13:55 Quote
cmc4130 wrote:
What I call the "pyramid method" of building jumps. Although some people pack the side and back almost vertically, this is not the most durable way to do things. In Mother Nature, all dirt wants to go "mountain shaped." Therefore the strongest structure is going to be much wider at the base than at the top.

I explained it over here:
https://www.pinkbike.com/forum/listcomments/?threadid=138473
and here:
http://forums.mtbr.com/trail-building-advocacy/i-kneed-ideas-my-new-trail-please-help-890432.html#post10869357

Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/Pyramid-Method-of-Building-Dirt-Jumps.jpg
Pic from Texas Toast jam in Austin, Texas. Once again, note how much wider the base of each jump is than the top.
Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/Texas_Toast_Dirt_In_Progress.jpg
Unsecure image, only https images allowed: http://www.lost-civilizations.net/images/mayan/uxmalpyramid.jpg
photo

Note how, even with filled in tabletops, the base is wider than the top, and the sides slant outwards.
Unsecure image, only https images allowed: http://i772.photobucket.com/albums/yy10/stickyfingaz/142.jpg
Cool

Thanks! I will pm you progress pics!
flag ricar
Posted: Oct 9, 2014 at 20:36 Quote
I used to ride with a bunch of kids who skimped on the beefiness of the jumps. The top of the lips would be about 4" thick and the landings would be about the same. They didn't last long at all before needing to be rebuilt. If you look at the pics cmc4130 posted all the lips are nice and fat, lots of support for them. They found out why that is a good thing when a (real fast racer) showed at the trails and pushed through a lip rupturing his spleen among other injuries. Don't skimp.

I also like to build my landings bigger than the lips, most i the pics are like that as well. It's nicer when you eat it to have a bigger landing.
flag gearhead79
Posted: Oct 10, 2014 at 3:53 Quote
We were lucky enough to have trails for about 8 + years,but had to deal for about 4 of those years of the forest preserve tearing them down and us rebuilding.they started as 4ish to 5 foot tall jumps ( there was absolutely no planning).when we figured it was time to go bigger we pitted in between every landing and lip about 3ish feet down.we did use the pyramid method.from a distance you could only see 4 feet of a jump until you walked up and seen the lip started below the rest of the land.the advantage we found with doing it like that was that the first 3ish feet of the lip was supported in the back and the sides.
The reason why we did it was because the dirt around us (light tan color and crumbly) was kinda crappy.in a matter of a day after watering the jumps it would turn light tan and was dusty as all heck!!!!!! we didnt have to add to the top of already solid jumps cause we weren't too sure how long the dirt would stay up there.
We did manage to make a 10 footer that wasnt pitted.we just kept throwing dirt till it was a giant pile and then formed it.again using the pyramid method.but being the stupid kids we were,we had a gap you could park an old Cadillac coupe de ville in so that jump only lasted a couple seasons.
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