# Dirt Jump Geometry



## Gonz (Feb 8, 2004)

To all those who build: 

Are your designs based on experience, or has anybody come across tables or formulas that apply to the geometry of dirt jumps ?


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## Djponee (Dec 20, 2006)

they just make them look gangster and it works perfectly


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## Jettj45 (Jul 25, 2004)

Yeah I wrote a java applet a while back that would graphically calculate jump and drop geometry.


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## creyc (May 24, 2005)

26" DJ frames tend to stick to a fairly common theme with either in-line or nearly in-line seat stays to the top tube, 69 degree head tube with a seat tube a few degrees more upright than that.

Check out some of the popular DJ bikes and you'll see the trend in geometry doesn't vary too far.


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## XSL_WiLL (Nov 2, 2004)

I think he's talking about the shape of the jumps, not the geometry of frames.


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## creyc (May 24, 2005)

oh...yea well i have no idea then. lol

i don't like jumps


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## Gonz (Feb 8, 2004)

*the geometry of dirt*

yes I am referring to the geometry of dirt. The few that I've made come out ok, but its a process of trial and error. No two environments are the same. There's so many variables. It is so much work moving dirt around. - it would be nice to get it perfect the first time. The pros with the bulldozers, and motocross ... how do they do it ?


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## snaky69 (Mar 8, 2005)

Practice, just like anything related to biking.


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## CountryBoy (Oct 24, 2006)

Just build some and see if they work.


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## .WestCoastHucker. (Jan 14, 2004)

Gonz said:


> ...The pros with the bulldozers, and motocross ... how do they do it ?


we've been doing it for over 20 years, that's how. before that, it was many years of trial and error...


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## combatkimura (Jul 17, 2007)

they gotta have at least 2' of vert, I know that for sure!

Maybe look for plans for wood kicker ramps for bmx and try to copy the transition radius with dirt?


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## heks (Jul 28, 2006)

combatkimura said:


> they gotta have at least 2' of vert, I know that for sure!
> 
> Maybe look for plans for wood kicker ramps for bmx and try to copy the transition radius with dirt?


really two feet of vert... huh... i dont know of a single place on this place(bike or moto related ) that has lips with two feet of vert... you would not be able to get through a line unless it was a bunch of spines... like hucker said its just trial and error... you will figure out the angles when you jumping it and it doesnt flow... the key here is FLOW


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## combatkimura (Jul 17, 2007)

I was joking about the 2' of vert, c'mon meow.


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