Wooden jumps. design, arc, height, dimensions etc.

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Wooden jumps. design, arc, height, dimensions etc.
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Posted: Jun 24, 2016 at 7:15 Quote
We've built a bunch of small wooden jumps that are 4'-5' tall with 6' radius in the picture below. They are neat little jumps but now it's time to build some large wooden senders for enduro/DH bikes. I'm thinking about 8' tall with a 10' radius? Working large dirt jumps to get them right is fairly easy but I don't want my wooden ones to look like a hack job. Is there a radius or rule of thumb in the jump building world that I need to make sure I follow? Any help would be appreciated.

Posted: Jun 24, 2016 at 9:44 Quote
Looks great,

I think for downhill biking the jumps look a little to short in my opinion. It really depends on the speed. If u got much speed then I wouldn't build them to high. Maybe 6' and a 60-75 degree angle.
And Maybe about 10' long.

Posted: Jun 24, 2016 at 12:36 Quote
Thanks- Yes I was just showing what we've built so far. These jumps are more like DJ's. I'm looking for info on building much bigger ones for big bikes. We will have all the speed we want.

Posted: Jun 24, 2016 at 13:57 Quote
Big bike, you will want more like 12' radius

Posted: Jun 25, 2016 at 15:53 Quote
So 8' tall 12' radius is a good start? If I go 10' tall same radius or go to 14'?

Posted: Jun 28, 2016 at 5:48 Quote
Look up all CMC4130's post. He always has amazing write ups on this. With diagrams and explanations.

Posted: Jul 15, 2016 at 12:15 Quote
allsk8sno wrote:
Big bike, you will want more like 12' radius

Agree. (at least when you're talking about big launches).

Most beginner builders build ramps too steep. Most ramps are actually mellower than people think. In BMX, the starting point should be radius is double the height. Like 4 foot tall 8 foot radius. Or 5 foot tall, 10 foot radius. Some ramps will go steeper, like 6 foot tall 10 foot radius. But a lot can also go mellower, like where the height is only a third of radius length, like 4 foot tall 12 foot radius--this is where you want more of a "sender."

Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/4foottall-8foottransition.jpg
Unsecure image, only https images allowed: http://i1239.photobucket.com/albums/ff509/austinmtbbmxalliance/Whistler-Blue-ramp.jpg
Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/degreesofarc.jpg
I like to post this photo to prove that yes, you can still go for tricks on a ramp that is not super steep. This one looks to be about 50 degrees of arc. That's where the height of the ramp is around a third of the radius length; like 5 foot tall 15 foot radius.....

Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/LakeJump_GregTait_photo_by_Octavio.jpg (Greg Tait rider, photo by Octavio).

best radius for 6ft kicker HELP!

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