Wooden Jumps. With pics

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Wooden Jumps. With pics
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Posted: Dec 23, 2015 at 16:42 Quote
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flag cmc4130
Posted: Feb 12, 2016 at 14:03 Quote
At Winter Park. "M" style flat-bank jump.

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Colorado Freeride Festival - slopestyle course jump
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flag tchach11
Posted: Feb 12, 2016 at 16:15 Quote
cmc4130 wrote:
anthonyp25 wrote:

so the length of where you put your string is how tall your jump is or the radius. ??

the length of the dotted line (the string) is the radius. if your "degrees of arc" go all the way up to 90 degrees, then you have a quarter pipe that goes right up to vert--in that case, the ramp's height and radius are the same, e.g. 8 foot tall, 8 foot radius. if your ramp is 5 foot tall with an 8 foot radius, it's like you're cutting 3 feet off the top of an 8 foot tall quarter pipe.

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48 Jump
About to build this... how does your 5' tall with 16' diameter kicker feel?
flag cmc4130
Posted: Feb 12, 2016 at 17:12 Quote
tchach11 wrote:
About to build this... how does your 5' tall with 16' diameter kicker feel?

What kind of bike will you be riding? I think 5' tall with 8' radius (16' diameter) is a little on the steep/poppy side of things. More of a BMX lip. It's pretty standard for BMX box jumps. I'd probably do 5' tall 9' or even 10' radius for 24"s and 26"s (mellower if it's intended to be sort of a "sender" type launch, where you want to clear a good gap...) I think it's better to err on the side of a jump being mellower and then just pull up and boost more, rather than for a shorter jump to be too lippy... But, that's just me. A lot of people think the other way...

I like to post this pic of Austin rider Greg T. You can see that the launch is less than 60 degrees of arc. Maybe only like 45 or 50, because it was designed to send you out into the lake, not straight up and straight down..... And he can still go for a double flip....

photo

Also on that landing drawing I did up there.... I'd probably make it like 35 degrees instead of 45. Even 30 or 25 degree landings are good, because the longer a triangle is, the more wheelbase/room there is to land on.

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photo
flag tchach11
Posted: Feb 12, 2016 at 17:19 Quote
The jump will be more for a DJ style jump. I don't have much run out so it needs to be more up than out. I'll have a big pile of dirt as a step up at probably 5' tall. Sounds like I'll be good. Thanks!
flag cmc4130
Posted: Feb 13, 2016 at 7:45 Quote
Bijou Bike Park, Lake Tahoe

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flag tchach11
Posted: Feb 15, 2016 at 15:37 Quote
HOT DAYUM!!! Those are sweet. Started framing my equally sweet jump today... opinions? It's 48" tall, 36" wide.

photo
flag cmc4130
Posted: Feb 16, 2016 at 11:11 Quote
tchach11 wrote:
HOT DAYUM!!! Those are sweet. Started framing my equally sweet jump today... opinions? It's 48" tall, 36" wide.

Looks very good. What radius did you end up using?
flag tchach11
Posted: Feb 16, 2016 at 11:42 Quote
15' diameter. We'll see how she rides.
flag Citrons
Posted: Feb 18, 2016 at 6:46 Quote
What slope angle would be ideal for a rollin?
flag cmc4130
Posted: Feb 18, 2016 at 8:19 Quote
Citrons wrote:
What slope angle would be ideal for a rollin?

Steep at the top, but then with transition (curve) at the bottom.

I have a thread over here specifically about roll-ins.
http://ridemonkey.bikemag.com/threads/roll-ins.228191/

Also check this out (if you want to think about the physics aspect):

http://zonalandeducation.com/mstm/physics/mechanics/forces/inclinedPlane/fourSecond/fourSecondInclinedPlaneJoyride.html
flag tchach11
Posted: Feb 18, 2016 at 9:14 Quote
How's this look for landing geometry. Not sure about roll-in speed so the distance of the jump can be adjusted on site.
Landing Mock Up
flag cmc4130
Posted: Feb 18, 2016 at 10:49 Quote
tchach11 wrote:
How's this look for landing geometry. Not sure about roll-in speed so the distance of the jump can be adjusted on site.

Maybe go a little bigger on the transitioned part of the landing? Maybe 10 or 12 foot radius? It'll connect a little higher up. But it will also add more space/wheelbase to land on. I know from experience that people want 10-12 feet to land on, sometimes even longer, depending how high and fast they're going.

Also, if you're not planning on building a deck/platform in between the launch and landing, then I'd suggest making the "platform"/"deck" on the landing more than 12". I'd say go ahead and do 2-4 feet. By making that "tag saver" type partial platform, riders will be less psyched out and will jump a bigger gap.

In practice, it's rare for people to have wooden gap jumps with no platform in between (except for maybe shows, where they want to set up portable ramps really quickly). At indoor bmx parks they always fill in the middle with a deck/platform. In BMX, it's known as a "box jump." Even though in theory it's not any different, there's just a larger injury risk; if someone bails to a dirt landing they can slide down the pyramid-shaped sides or even land in the soft dirt on the backside.

The best box jumps also have a rounded-corner on the landing. This is because people frequently tag their back wheel.

photo

At the Whistler Air Dome, they did a step-up box jump with a rounded corner landing like this:

photo


Some box jump landings have radius throughout, like this.
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I guess this one does have a launch ramp and wood landing with a gap.
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Another great example of a step-up box jump with a rounded-corner landing.
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flag Citrons
Posted: Feb 18, 2016 at 11:24 Quote
cmc4130 wrote:
Citrons wrote:
What slope angle would be ideal for a rollin?

Steep at the top, but then with transition (curve) at the bottom.

I have a thread over here specifically about roll-ins.
http://ridemonkey.bikemag.com/threads/roll-ins.228191/

Also check this out (if you want to think about the physics aspect):

http://zonalandeducation.com/mstm/physics/mechanics/forces/inclinedPlane/fourSecond/fourSecondInclinedPlaneJoyride.html

Thanks alot, had trouble when googling rollin, to much limp bizkit references Big Grin
flag tchach11
Posted: Feb 18, 2016 at 20:02 Quote
cmc4130 wrote:
tchach11 wrote:
How's this look for landing geometry. Not sure about roll-in speed so the distance of the jump can be adjusted on site.

Maybe go a little bigger on the transitioned part of the landing? Maybe 10 or 12 foot radius? It'll connect a little higher up. But it will also add more space/wheelbase to land on. I know from experience that people want 10-12 feet to land on, sometimes even longer, depending how high and fast they're going.

Also, if you're not planning on building a deck/platform in between the launch and landing, then I'd suggest making the "platform"/"deck" on the landing more than 12". I'd say go ahead and do 2-4 feet. By making that "tag saver" type partial platform, riders will be less psyched out and will jump a bigger gap.

In practice, it's rare for people to have wooden gap jumps with no platform in between (except for maybe shows, where they want to set up portable ramps really quickly). At indoor bmx parks they always fill in the middle with a deck/platform. In BMX, it's known as a "box jump." Even though in theory it's not any different, there's just a larger injury risk; if someone bails to a dirt landing they can slide down the pyramid-shaped sides or even land in the soft dirt on the backside.

Man... you are a wealth of knowledge. Thanks! The landing is actually dirt, but I'm going to try to shape it to dimension. Solidworks has sand as an appearance so it looks like wood. Here's my dirt pile shaped into a bad jump. By using the wood kicker I can use all the beautiful, precious dirt as a landing. DH bike in for scale...
Backyard DJ

 


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