# dirt jump info



## GaspinForAir (Jun 19, 2012)

This may be the wrong place to ask, but i have been slowly making a trail in my backyard and started off with dirt jumps. Working on my third one i may try to do it different than the other 2 but have questions to see if its really what i wanna do.

The 2 jumps i have finished are about 3ft tall and i'm always working on the curve/angle of the takeoff jump. Now i know a steeper angle is suppose to make you go higher on the jump. But lets say i have an angle i'm liking on my jumps, what would happen if i make the new jump taller than 3ft but have the same angle? Would it make me jump higher, further, both, or what?


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## cmc4130 (Jan 30, 2008)

check out this thread:

http://forums.mtbr.com/urban-dj-park/dj-pump-track-plans-402237.html


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## GaspinForAir (Jun 19, 2012)

thanks for the link. 

Suppose to rain here tomorrow and was looking to add another 1/2 - 1 foot to this jump in my backyard to make it around 3 - 3.5ft tall, but wanting to keep to same angle i have. 

oh yea, the best i could measure today i think their only 2.5ft tall instead of 3 like i stated in first post. also the pics are not of the new jump i was talking about in the first post. I think i will leave it alone for now and work on this one.

here are the pics of the jump i'm wanting to try and make a lil bigger


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## cmc4130 (Jan 30, 2008)

GaspinForAir said:


> thanks for the link.
> 
> Suppose to rain here tomorrow and was looking to add another 1/2 - 1 foot to this jump in my backyard to make it around 3 - 3.5ft tall, but wanting to keep to same angle i have.
> 
> ...


I would suggest adding a lot more dirt to the landing. It'll have to be wide at the base. Landings are actually more important than launches to have smooth dirt jumps.


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## RidingMyTrail (Oct 7, 2012)

That jump looks a little low. See how the front wheel is going to come off the jump before the rear wheel compresses into the face of the jump? In essence, that jump is a kicker and the rebounding rear suspension will tend to kick the rear and since the front is in the air when that happens, you are set up for an endo. These jumps can be fun for an experienced rider, but are tricky for someone who isn't expecting it.

Looks like you have a nice kudzu crop going too.


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## cmc4130 (Jan 30, 2008)

RidingMyTrail said:


> That jump looks a little low. See how the front wheel is going to come off the jump before the rear wheel compresses into the face of the jump? In essence, that jump is a kicker and the rebounding rear suspension will tend to kick the rear and since the front is in the air when that happens, you are set up for an endo.


He appears to be riding all-rigid. ; )

I think the launch looks fine for the size that it is. It appears to have a good transition.
If a rider can do a good front wheel first bunnyhop (or j-hop as some call it) on flat ground, then they will know how to pull up the front end normally even off a curb high lip, you're not gonna endo.....

I know what you mean though about getting bucked by rear suspension. I have to remind myself to preload whenever I go ride downhill. Stomp down both feet BEFORE you hit the jump, then it's rebounding out as you go up the launch ...


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## GaspinForAir (Jun 19, 2012)

i have done some buckin, i call it half squash jump. Where i soak up the the jump with my arms but don't with my legs


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## cmc4130 (Jan 30, 2008)

This is an example of a 10 foot gap jump that would be called a "rollable double" in the bmx world, or "camel back" by some (dorky) people 

My main advice is don't go shorter than 9 or 10. If you're going at a reasonable pace, you will learn to clear that distance pretty easily. The key is just to keep the launch and landing mellow. Later you can build it steeper for more of an up-boost.










Similarly, this was an early version of our main table. It's deliberately mellow for cruising fast and low.










Even with a jump that mjellow, you can pull up and boost and get some decent air. The jump itself does not need to point straight up in order to go up.

View from the other side:


















Here's another old pic from WCPT. Back when I was first laying it out. Use the hillside for a natural step down. Measure out the distance to the roller and then to the next lip. It MUST be spaced appropriately. 









Later on, we started building the jumps up.










Having the landing stepped-up from the launch may look harder or more intimidating at first, but it's actually easier to manual, and when you jump, you have more wheelbase of landing to land on:









Even dogs can run over a rollable-double.









Note how all the corners are rounded off on a pump-jump track. I was emphatic about this design. A lot of the bmx scene is obsessed with making hard corners that look like dirt versions of wood ramps. That's cool and I can respect it. But when you're deliberately going for a pump-jump track, wheels need to have rounded edges to roll over. Note the roller-table before this jump. The corners are completely rounded off. This allows you to "scrub" i.e. stay close to the track and fully pump the roller-table.










More to come, if this is helpful. I really need to put everything together into a book.


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## GaspinForAir (Jun 19, 2012)

sweet pics! and yes the rollover jumps give me a fit for some reason. I trouble with them on the bmx track i've gone too a few times and it seems to be the kind of jumps i find on some mt bike trails around this area. If u notice i have mine kinda squared off and i have no problem jumping or at least compared to other peoples jumps i have come across. i dunno if its that or if i have more angle on my jump, or just know how to jump mine since i ride them everyday.

i took and dug out a little bit more from the front of the jump, maybe almost 6 inches. Didn't really effect my jumping any, but i think it did smooth out the bottom of the transition more which is a plus. 

Got a couple jumps in and the chain snapped on my dirt jumper,so i grabbed the bmx and jumped a couple times.


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