Jump building tips

[CCC4]

Hey, I am wanting to build a jump at my place that would leave from a flat field, gap a 20 ft. creek and land in a powerline right of way that is approximately 15 feet higher than the field. I have a general idea of what to do however I over-think everything and need some suggestions for the actual jump face such as pitch and size. Speed is not a factor, I can get a huge run at it. Thanks!

[bhsdriller]

lots of dirt

[Zondebok]

I read that as "Tips for how to jump a building", and thought this would be a pretty interesting thread

So, worst case scenario, how deep his this creek??

[CCC4]

I read that as "Tips for how to jump a building", and thought this would be a pretty interesting thread

So, worst case scenario, how deep his this creek??

Dang your right, it does look like I'm offering tips instead of needing them, sorry. The creek varies from 2ft to dry. The steep bank on the other side of the creek is possibly the worst part of it, literally 15 ft almost straight up.

[Zondebok]

OK, so, worse case scenario, you hit a 15 ft wall of dirt....

I have no idea how to properly build a jump, but hopefully you will get some response. Interesting question.

[CCC4]

Yep! I will hit the wall! LOL! I'm thinkin that it is just a big assed step up. This jump will be the connecting link of my Enduro X course up to my 7 1/2 mile woods course. I think it's do able, jus sketchy as hell!! I hope I get some replies, then maybe I could document with pics, the construction and execution (thats harsh) of the jump!

[HyperGlow]

Were you thinking to dirt to dirt or a man made ramp? We made a wooden ramp using 4x2 framing and 8x1 boards to ride on with a kick in it which we can jump about 30ft on and about 10ft high, we definitely needed a down ramp though the landing was SO hard! We have been using a pile of bark for the down ramp which worked really well and was good cushioning but we are thinking about using a stop bank near a river for the down ramp as there is more of a run up.

[CCC4]

Were you thinking to dirt to dirt or a man made ramp? We made a wooden ramp using 4x2 framing and 8x1 boards to ride on with a kick in it which we can jump about 30ft on and about 10ft high, we definitely needed a down ramp though the landing was SO hard! We have been using a pile of bark for the down ramp which worked really well and was good cushioning but we are thinking about using a stop bank near a river for the down ramp as there is more of a run up.

Dirt to dirt. Where i am wanting to land rolls out pretty good, hoping to not need a landing pad, the landing keeps elevating but really gradual.

[dmm698]

Yikes, If the landing is elevating that is going to be HARSH. If it was downgrade, or even flat it wouldn't be that bad because even though your going 20 foot up or so your landing is 15-20 foot up as you said so it woudlnt be that bad but landing on some elevation is sketchy and harsh.

[CCC4]

Putting a transit on it 2moro to see exactly what I am dealing with, was looking at the jump site this evening, if I can hold my front end up i should be ok. Over shooting would be the best scenario. On a jump like this how do you measure distance? I was thinking you would have to figure straight up from the edge of the take off then try and figure the horizontal line to the landing spot???

[indy rider]

Sorry, I don't have any helpful ramp building info for you but I'll be anxiously waiting to see the video of the first attempt. Don't forget to film it.

[pentaxis]

What ever happened with this? I would love the follow up!

[suzukimxrider97]

if all youre trying to do is connect two trails, would it be an option to build a bridge across the river? Nothing big, just a few 2x4s hammered into a ground and somehow have a 2-4 ft wide bridge to cross

[CCC4]

What ever happened with this? I would love the follow up!

Yep it's been awhile. Im struggling to end my HS season on the podium and haven't been willing to finish the jump (no room for injury ). The hill is still there... Ha! My last race for the year is in a couple weeks, got a skid steer here and a buddy that wants to see the jump made so I need to "sack up" and make it. Don't worry it will be videoed. Thanks for askin, kinda adds a little spark back!

[Blutarsky]

You need to do the trajectory math. Most MX track builders recommend a 30 degree ramp angle, from what I have heard. If you make the face too big, it may take away from the compression rebound timing, and you will not jump as high. Figure a 6' high, 30 degree ramp. That means the actual face will be 12' long (along the hypotenuse)

To get a rough idea of how fast you will have to hit it.and what your landing will be like...here is a trajectory calculator:

http://convertalot.com/ballistic_trajectory_calculator.html

You have to convert to and from metric.

Since normal dirtfall angle is about 35 degrees...the ramp peak will need to be well back from the creek. There is also likely a slope down to the creek from where you can build the ramp. This will push the ramp further back. Finally...the bank that is 15' higher...probably has a pretty good angle as well. This will add some horizontal distance. Assume you can make a 6' tall, 30 degree ramp. You need to know distance, horizontally, from the top of the jump...to the point you want your front wheel to touch down. Then you want to know the height from the top of the ramp to the touch down point.

Making some quick assumptions about the shape of the creek bed, etc, I calculated that your elevation gain will be 9' (15-6), and the horizontal distance will be close to 70 feet. Note that if you landed at the same elevation as you took off...like a normal jump...this would be equivalent to a 90' jump! Since you are stepping up...it will not be as far, and the landing will be softer....assuming you do not case the 15' bank.

You will need to hit the ramp at at least 39 mph, NOT taking any gains or losses from suspension rebound-compression into account! If you hit it at 37...you will case the face at nearly a 60 degree angle. Don't do that. If you hit it at 42 mph, you will be 20' safe beyond casing it. You landing wont be much harder than if you barely made it. I have no idea how much suspension rebounding will add to height... I suspect it could be a LOT. Meaning the effective trajectory angle could be higher than the ramp angle, due to rebound effect. In this case...you will fly higher and farther.

Proceed at your own risk....

Make sure the batteries in the video camera are good....

Edited December 11, 2011 by Blutarsky

[Dylan105]

i have a track at my house but no jumps where if i case i die.

your going to need a steep upramp, but dont be a tight ass with dirt because it has to be tall for the bike to actually ride off the lip instead of boucing off the lip.

thats a video on my youtube channel and theres a jump kind of like what your talking about at 37 seconds and a couple of other times in the video, have fun

[Blutarsky]

Sick sick goon riding..... Major talent to go that big ....that bad. Who is that....must be a pro level rider...

[SOAB_465]

I think it's jimmy albertson?

Being a step-up it's gonna be a nice soft landing as long as you make it clean. I'd say try making a couple ski jumps/singles to flat, until you can make a face that feels decent. You won't be able to roll the step up your first time, if there's a creek on the other side.

Once you're comfortable prepping a jump face so that it doesn't need to be rode into shape, just build it high enough that that you won't auger straight into the other side. If your ramp is 15 ft high, then it will ride like a step on, and at worst you'll probably clip the lip rather than smack right into it.

Hope this turns out, sounds like you have a really awesome riding area as long as you don't get hurt

[CCC4]

Hey, Thanks everyone ! You guys have compiled ALOT of awesome info for me. Went out this weekend and was going to work on it but all the rain and frozen ground has made it to where the skid steer ain't doin so well. Yep I am definately going to have to go big with the take off and that is where the conversion chart supplied above is going to be a huge help! (thanks for that) Soon as I get mud to work better for me I am going to start in on it. I wish it wasn't such a dangerous jump attempt, but if done right it should work out! Thanks again everyone for all the info!

[Dylan105]

shit sorry i posted the wrong video hahaha ! my bad,

http://www.youtube.com/watch?v=cu6mQg-c2oE

once again at 00:37 there is a jump kinda like you described