# back yard dirt jumps



## milenine (Feb 12, 2007)

I don't have much land to work with (.5 acre) but would like to build a couple of dirt jumps in my back yard. I recently got done putting in a pump track after I bought the "Pump track Nation" book from www.leelikesbikes. It is really fun and now I want to step up the backyard action with some medium sized jumps.

Question: Is it a problem that the yard is so small that the fastest I can get going to hit a jump is about 15-16 mph? What kind of air could I expect at this speed... and how tall of jumps should I try to build for maximum air? gap length? There is really no DJ scene where I live so your help is appreciated. What would you say a average speed is for DJing?


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## sittingduck (Apr 26, 2005)

build a big, tall, steep roll-in. Then you can probably get 2 or 3 sets of doubles in there as big as you want em. (and you won't have to pedal!)


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## the_godfather (Jan 19, 2007)

a picture of the land you got would help


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## crazy Jim (Mar 31, 2005)

heres a roll-in for ya. 12 ft tall leading to a 4 ft tall wood kicker to a 14 ft gap.


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## milenine (Feb 12, 2007)

I hadn't thought about the roll-in. Nice picture. Thanks. Untill I get enough dirt/lumber for a roll-in... Any one have any ideas of what an average DJing speed is... I know it is going to vary, but is it 15-20ish or more like 25-30ish? What do you think someone could do with 15mph of pedaling? Jump size/gap height?


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## Cru Jones (Aug 10, 2006)

Dude, I don't think anyone pays attention to their speed in mph when they they are DJing. Either build a roll in, or make the the jumps gradually increase in size. Make the landings tall and steep so you can pump them to get speed for the next jump. You can be going very slow and still clear a jump with a 5 to 10 foot gap. Maybe start there and work up to like 15 or 20 foot gaps.


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## milenine (Feb 12, 2007)

yeah. I figured no body would know what speed they are hitting jumps at... but it is relavant when you have very limited space and no drop in. I don't want to shovel a bunch of big jumps and then not be able to clear them. I like the idea of starting them smaller and building up. Anyone know where any internet plans are for building a drop in out of wood?


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## opjones (Apr 11, 2007)

Dude, if you already have a pump track, then that's where you should get your speed from. Throw a line right off your pump track, bingo bango, speed, air, excitment, b1tches, money, everything!

And what Cru said


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## Cru Jones (Aug 10, 2006)

opjones said:


> Dude, if you already have a pump track, then that's where you should get your speed from. Throw a line right off your pump track, bingo bango, speed, air, excitment, b1tches, money, everything!


Good point.

Nice to see you round these parts. Op has made it over to the darkside...


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## WaveDude (Jan 14, 2004)

I put a bike computer on just for grins to see how fast I was hitting jumps at. On our main line which are only about 4' tall and with gaps of 11, 12, 13, and 13 feet I max out at 18.5mph and the start is considerably slower. We have one jump about 5' tall with a 15' gap and I hit that at about 17mph. So if you can get up in the 12-15mph range on your pump track you can build a nice little set off to the side and transfer into it. And this is on a SX Trail. If you've got a hardtail you'll need even less speed. It doesn't have to be huge to be fun, just make it flow.


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## opjones (Apr 11, 2007)

Cru Jones said:


> Op has made it over to the darkside...


Yeah i figured it was time to sign on up.
:rockon:


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## milenine (Feb 12, 2007)

Thank you WAVEDUDE that is exactly the kind of info I have been looking for. Sounds like I need to learn how to jump. I ordered a dirt jumper that will be here in a few days. Right now I am riding the pump track on a Cannondale prophet and it sucks up a lot of the energy. How steep of a lip do you have to clear a 15' gap at 17mph?


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## crazy Jim (Mar 31, 2005)

how high and how far you wanna go will determine your steepness. We have 16+ ft gap with a lip only about 18 inches high and very mellow. In the same line we have a lip that is nearly 5 ft high with a 15 ft gap. 3ft tall lips with a radius of 6 ft (similar to most of my wood kickers) are the norm at most of out jump sites with an average gap of 11-12 ft) If you build a 5 ft high lip with a similar radius as mentioned above and wish to clear 15 ft gap you are talking about major league air time. Also, speed is very subjective. Some guys go slow but boost real high, others can go faster and stay lower and clear the same gap so it all depends on your riding style or what style you choose to use at that particular moment.


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## milenine (Feb 12, 2007)

Thanks Crazy Jim. When you are refering to the lip height in your last post are you talking about the total height of the jump?... if not what exactly defines where the "lip" starts....


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## jimage (Dec 22, 2006)

i wish i had land to build on:cryin: :bluefrown: :sad:


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## crazy Jim (Mar 31, 2005)

lip height=maximum verticle height of the jump/kicker


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## TXneedmountain (Feb 14, 2007)

hey man I was thinkin of buyin the lee's bike pump track book how is it?


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## stubecontinued (Mar 14, 2007)

I have a similar situation 7/8 of an acre, but I made it work... will take and post some pictures...


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## crazy Jim (Mar 31, 2005)

all this in a half acre


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## cameraboy (Apr 13, 2007)

crazy Jim said:


> all this in a half acre


wow. i'm jealous. i tried to make some jumps on my hunting lease, but its like a desert out there and theres like no dirt.


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## milenine (Feb 12, 2007)

Lees pump track book saved me so much time. I was just going to go for it after looking at some pump track pictures... but it is a real science doing it correctly and the book helps you avoid learning from trial and error. I still made some errors when I ignored the books advice, but now have them straightened out. He really covers everything you could imagine and a lot of things you would never think of on your own. I have .5 acre with a house on it so my space was limitited. I just followed one of the plans in the back of the book and it took me 4 full dawn-til-dusk days to build it. I used only a shovel and a rake. Luckily the snow had just melted and the ground was soft. I don't think I could do it that fast now unless I had some machinery to move the dirt around. Nice pics camera boy.


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## jimage (Dec 22, 2006)

ive got about a 20-10 meter garden.............

...........and its flat


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