[XGrantX]

hi there. Im currently in the process of building a four pack, rhythem style. Im just wondering what other peoples techneques are for working out the spacing between the jumps, length of up-ramp, length of table(span) for a given height etc. There are no experienced dirt jumpers in my area. The advice i was given was to try and have the up ramp twice as long as the jump is high. This seem to be making the jumps too flat. If anyone has advice they could give me it would be apreciated. Height needs to be around 1m to 1.5 high.
Also the jumps will be for 26er's

Thanks Grant

 

[Miagi]

Im kinda in your position as well. But I figured Id just go up the jump and then jump off my bike. Then Ill put a landing around where I landed. Not too great, especially for bigger ramps.

 

[don]

Can someone make a sticky with this? Below is some great info from one of the 9th St Trails locals. Anyway, a cut a paste from a post I had on Hcor a while ago...

I'm more of a look and feel and most of the time have to rebuild builder. But, there are some great posts by this dude Wheelie Nelson on the Vintage BMX site:

I'm not sure who Wheelie is exactly, but it sounds like he's a 9th St Trails local - and really knows his stuff. Check out this CAD drawing of a new trail spot:

Best exerpts from the VBMX thread.

The downslope for a start is good.
You might want to find out who owns the property before you get too involved with your time. Nothing's worse than working for months to get things going only to find them leveled one day.
Secluded park land and floodplain areas are the way to go.
You'll want to bury some big logs, big rocks, etc. to save dirt.
If you have the money and a dumptruck can get down there then I would go ahead and buy some good dirt. I don't know how good the dirt is there so that's always an option. You can build a pretty nice set of doubles with two loads of dirt. Time is $ and it takes forever to fill up 50 wheelbarrows.
A general rule is to have about twice the distance between the top edge of the landing to the top edge of the next lip as there is between the gap of the previous jump.
Therefore, a 12' double should have around 24' to the top of the next lip. (I've measured 9th street before and this is what works best.) You don't want to cram things too close together because then you can't make things bigger without moving what you've built and the pits between jumps feeling too quick.
Of course mix in some rollers, hips and berms in there somewhere.
Hopefully there is somewhere to get water too.
Also, try not to point the jumps toward the sunset. This is a problem on a few jumps at 9th street and you don't realize it until you've built things already.
Another thing you might want to do since it's level is to have a line coming back toward the start for obvious reasons.
I've been building stuff for a very long time so let me know if you have any questions

A lip 5' feet tall with a 9' tranny will give you around 10' of distance.
A 5' lip with a 10' tranny will give you around 12' feet of distance. You can cut some templates out of wood to help guide you if you're not good at shaping lips.
A regular dumptruck (no trailer) is 12 cubic yards.
If you bury a little something and have one load dumped on the lip and one dumped at the landing you can take some dirt from the lip and throw it on the landing and get a decent jump out of it. Around 5' tall.
If you want to make big jumps and you have the money then one load for the lip and two loads on the landings.
A typical load will run you around 60-80 bucks delivered.
The dirt itself is only about 2 or 3 bucks per yard if you can pick it up yourself. It's the delivery that's expensive.
Also, make sure you get it dumped as close to the right spots as possible because it is a major pain to move an entire load just a couple of feet with shovels.
Get dirt with some clay mixed in.
Usually, if you're buying a lot, you can go down in the pit and pick your own dirt from the local supplier.
Here's a place here in Austin that I designed and had built:
http://photobucket.com/albums/v389/9th_street/New Place/

Hopefully you'll have some help because it's a lot of work.

 

[sb317]

I'm with don. I look at the jump while building and see if it looks like it's going to work. I judge the distance and steepness by the speed I think I'll be carrying when I get to that section. I sometimes have to tweak something here or there but I'm getting better to where it works the first time now.

 

[ÆX]

is that what they call REDBOX?

if you building area is flat this all works.
if you have a grade you will need to think
more about the speed you will be getting
from jump height changes.

 

[musicman]

thats what red box was planned to look like only 2 of those lines got built tho and a 3rd not planned one two, i think planning your jumps that in depth is silly. i say build the first set, make it work see how much speed you have, build your second set , no pit, if its too long dig a pit and unsteepin the lip if its two short super steepen the lip and or make it a step up, jumps are all trial and error. and the more you build the closer to accurate your guesses will get

 

[don]

I agree, I think it's very hard to plan trails in that much detail, but for someone just starting out - as the original poster or someone making a plan for a town/city dirt jump park it's really good. The side detail with the gap, radius, and distance between sets is a good start.

 

[cmc]

so much for not planning things in detail.

check this out:


http://www.progressiveparkdesign.com/Texas_X_Park_Dirt.pdf


http://www.bustedspoke.com/Forum/viewtopic.php?t=28224

 

[boostindoubles]

yea, I used to build a lip first, like I wanted it. Then I'd eye out how fast I thought I'd go and then build a landing, and go jump it. If I could clear it the first time, I'd move the landing back until I had to hit the jump well to clear it. From there I build up a good landing and have fun. Until I get bored with that and reshape it into something else.

build, jump, reshape, you'll get good at building the more you do it

 

[skatetokil]

so you're saying you build your doubles so that an off jump is a case? I would think you would rather risk having a boosted jump put you too deep in the tranny rather than risk a nose case on the back of your lander.

 

[OGRipper]

so you're saying you build your doubles so that an off jump is a case? I would think you would rather risk having a boosted jump put you too deep in the tranny rather than risk a nose case on the back of your lander.

I've hurt myself more from over-shooting than from casing, and I think it's good to build a little bigger than you can easily clear on your first few jumps.

 

[cmc]

here's a classic:

http://video.google.com/videoplay?docid=-1329751209494773046&hl=en

 

[musicman]

so you're saying you build your doubles so that an off jump is a case? I would think you would rather risk having a boosted jump put you too deep in the tranny rather than risk a nose case on the back of your lander.

well you can avoid that by not fully commiting and landing back heavy the first few times you do it. becuse if you build a jump and the first time you hit it its perfect, i garuntee you will be overshooting it alot after a few runs. learn to bail and case b4 you learn to jump it will save a few bones, although it is really hard to toss your bike for the first time.......

 

[XGrantX]

Diggers coming at 8:00 tomorrow. Oh the anticipation!

 

[skatetokil]

bailing and casing suck.

 

[GuettoBlaster]

I'm with don. I look at the jump while building and see if it looks like it's going to work. I judge the distance and steepness by the speed I think I'll be carrying when I get to that section. I sometimes have to tweak something here or there but I'm getting better to where it works the first time now.

\Thats a whole bike aprk right there!! you getting very serious about it!!! awsome work!!!

 

[boostindoubles]

so you're saying you build your doubles so that an off jump is a case? I would think you would rather risk having a boosted jump put you too deep in the tranny rather than risk a nose case on the back of your lander.

over shooting is painful man. If you know how to bail out of a jump, it's pretty easy to do and not get hurt. and 50/50'ing landings have saved me from getting hurt lots of times.

besides, why build something that I know I can clear? I try to push my riding by building stuff that I have to work for. and like musicman said if I clear it the first time, I'm definitly going to be over shooting it all the time once I get the line dialed.

 

[skatetokil]

fair enough. I'm just learning to jump and casing scares the crap outta me, but I can see how watching the tranny drop away below you and coming down 10 ft to flat would suck pretty bad too.