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Ideal lip radius?

sittingduck

sittingduck

Turbo Monkey
Jun 22, 2007
1,958
2
Oregon
I am going to help build some indoor jumps for the winter, and the lips will be wood kickers.... dirt landings with some hay bales in between to make faux tabletops.

Anyone have an idea what the perfect shape will be? Lips will be 6 feet tall, gaps probably 10-12 feet, possibly more. Mostly designed for 26" wheels, but all sizes will be welcomed.

I was thinking maybe a 10 foot radius? Or possibly a compound radius, with maybe 9' for the first 3 or 4 feet, then mellowing out to 10'?
 
Beast

Beast

Turbo Monkey
May 23, 2002
1,579
0
Where the riding is good
The typical skatepark quaterpipe radius is 7-9 feet. Because this park is intended for mountain bikes, the lips should probably fall on the mellower end of that range. Say 8-9 feet.

A good rule of thumb for a pretty poppy jump: make the ramp height between 60% and 75% of the radius. So for a 6' tall lip, you'll want between an 8 and 10 foot radius.
 
sittingduck

sittingduck

Turbo Monkey
Jun 22, 2007
1,958
2
Oregon
cmc said:
how much space are you gonna have ?
Click to expand...
Not sure about the actual square footage... it's a big area though. It's part of the livestock area at the Salem Fairgrounds. Last year, there were 3 jump lines, a pump track, a hip/quarter and a bark jump.
 
chuffer

chuffer

Turbo Monkey
Sep 2, 2004
1,570
912
McMinnville, OR
sittingduck said:
Not sure about the actual square footage... it's a big area though. It's part of the livestock area at the Salem Fairgrounds. Last year, there were 3 jump lines, a pump track, a hip/quarter and a bark jump.
Click to expand...
when is work starting? I am a 5 minute ride from the fairgrounds and would be willing to volunteer time and sweat.
 
sittingduck

sittingduck

Turbo Monkey
Jun 22, 2007
1,958
2
Oregon
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cmc

cmc

Turbo Monkey
Nov 17, 2006
2,052
6
austin
sittingduck said:
Not sure about the actual square footage... it's a big area though. It's part of the livestock area at the Salem Fairgrounds. Last year, there were 3 jump lines, a pump track, a hip/quarter and a bark
jump.
Click to expand...
how about jump track (loops instead of lines)?
 
cmc

cmc

Turbo Monkey
Nov 17, 2006
2,052
6
austin
to me, the 45 degree arc (half of a quarter pipe, or 1/8 pipe)
is pretty ideal for a combination of height and distance.

this thing appears to be about 6 feet tall with a 12 foot transition.

but 5 foot tall 10 tranny, or 4 foot tall 8' tranny, would be the same principle.

 
Cru Jones

Cru Jones

Turbo Monkey
Sep 2, 2006
3,025
2
Hell Track
45 degrees is probably the best for distance and also gets you good height, but I like to have variations in steepness at the trails and generally prefer jumps that are a lot steeper.

Check these jumps. Both of them have gaps that are maybe only 10 to 12 feet, but the lips are tall and steep. You can blast them....





 
cmc

cmc

Turbo Monkey
Nov 17, 2006
2,052
6
austin
kidwoo said:
I like how the 30 degree and 60 degree trajectories put you in the same place.


That says nothing with regards to speed.
Click to expand...
I'm assuming the graph uses the same speed for all three trajectories.

So, in the same line, you could have a 30 degree set with a 15 foot gap followed by a 60 degree spot also with a 15 foot gap. But if you put a 45 degree takeoff in that same line, you'd have to make the landing 16% longer. 15 X 1.16 = 17.4'. Interesting huh.

When gap distances aren't matched up with angles and speed is when riders have to use more body english to make it work. Sometimes that's fun. Other times it just doesn't work.

 
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Cru Jones

Cru Jones

Turbo Monkey
Sep 2, 2006
3,025
2
Hell Track
So, I was thinking about this thread while I was at the trails today and realized I could download an inclinometer on my iphone, so I did. Most of our jumps are in the 65 to 70 degree range. This one is about 70...



Even our "mellow" one is about 55...



Not that it's any better than a 45 lip. But I know it works and it's fun. I think most bmx type jumps are steeper. I don't think I've actually ever hit a jump that was 45 except maybe at the bmx track.
 
Cru Jones

Cru Jones

Turbo Monkey
Sep 2, 2006
3,025
2
Hell Track
Love it. This vid might do a little better job of showing how MASSIVE they are. Long and steep. I'd be scurred...

http://www.youtube.com/watch?v=<object width="700" height="440"><param name="movie" value="http://www.youtube.com/v/XhjslyJN_Qw&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/XhjslyJN_Qw&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="700" height="440"></embed></object>
 
sealclubber

sealclubber

Monkey
Nov 21, 2007
543
10
Cru Jones said:
So, I was thinking about this thread while I was at the trails today and realized I could download an inclinometer on my iphone, so I did. Most of our jumps are in the 65 to 70 degree range. This one is about 70...


Even our "mellow" one is about 55...

Not that it's any better than a 45 lip. But I know it works and it's fun. I think most bmx type jumps are steeper. I don't think I've actually ever hit a jump that was 45 except maybe at the bmx track.
Click to expand...
your numbers sound spot on. ive never done measurements but the jumps i ride and build are built "just less than vert". meaning we stack and shape them to where we think we cant even gap it, but somehow do. we shape em almost like a quarter, but pretty reliably go 2x the height of the lip in distance.

and to be a dork, that inclinometer wont quite be accurate because of the sexual thrust of your body (i mean hump) to pump the trannys. ick
 
cmc

cmc

Turbo Monkey
Nov 17, 2006
2,052
6
austin
sealclubber said:
. . . the jumps i ride and build are built "just less than vert". meaning we stack and shape them to where we think we cant even gap it, but somehow do. we shape em almost like a quarter, but pretty reliably go 2x the height of the lip in distance. . . .
Click to expand...
2x height in distance.... how long do you think that last set was in the video? looks like 25 feet or so.

that last set that everyone was casing in the video made me think of this thread because the transition on that last lip seemed a little steeper than the ones on the rest of the line. seemed like either you soaked up the pop or you had to go suuuuper high to make the distance.



http://www.experiencezerog.com/parabolic.cfm







 
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