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Roll-ins

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
still trying to find out if anyone has clocked the mph speed of riders at the bottom of the roll-in before hitting the mega ramp gaps. . . . .




if you can believe this . . . you need about 60mph to clear 120 feet.


http://www.silverfish-uk.com/content/news_about_cove-bike-frames.php?articleshow=537



Cove News
World Record Mountain Bike Jump
Intense Tires pro-rider Nathan Rennie goes for the longest mountain bike jump of all time.
When the MTB race season is over, some guys just kick back, relax, and start thinking of the next years season. Not Intense Tires sponsored Pro Nathan Rennie. Nathan has been talking about setting a World Record Mountain bike jump for quite some time and he went for it this week. Here is some info on the jump attempt.

Nathan Rennie just rang from the Red Bull Jump Site in the Painted Desert of South Australia with news of his 121 foot record jump. Nathan was towed in by a motorbike at 96 km/hr (60mph) and piloted his Santa Cruz V10 Downhill Mountain Bike the 121 feet from ramp to landing. He flat landed the front wheel and "blew up" three quarters of the way down the landing ramp.
Nathan separated his shoulder and smashed his prized TLD full face helmet, as well as sustaining cuts and bruising to most of his body. The jump has been classed as "unofficial" by the Guinness Book of Records because of the crash on landing, which has prevented any further attempts at this time.

However, Nathan is elated with his effort and feels the setup could be used for much bigger jumps in the future. After viewing the raw film footage, Nathan and the Red Bull crew were stoked with the jump, and are looking forward to putting together the half hour package for Red Bull on free to air T.V.

For more information on Intense tyres please see www.intensetires.com

Published Friday 13 January 2006


Hoffman also got towed by a motorcycle for his high air record. I think I remember Steve Swope saying they were going about 55 mph.

 
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pnj

Turbo Monkey till the fat lady sings
Aug 14, 2002
4,697
40
seattle
mega ramp is just gravity fed, correct?

run some math... height, angle of ramp, weight of rider, etc. you'd get a rough estimate.
 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
. . . .
run some math... .
heh, i know, but i only half-remember the physics. (i was a liberal arts type). like gravity acceleration . . = -9.8m/s² . . . then with the inclined plane, it slows that down somewhat. the steeper the better for speed obviously, but a person also needs to transition from perpendicular to horizontal without too much g-force...

these local guys built a roll-in (which i didn't ride) but i heard was pretty rough. it could have been taller but less steep for a smoother drop-in. or it could have had a larger radius tranny at the bottom....


so was the HellTrack drop-in 'RAD' or jackass-steep ? Cru?




http://www.themovierad.com/2010_11_01_archive.html



http://www.physicsclassroom.com/class/vectors/u3l3e.cfm
 
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pnj

Turbo Monkey till the fat lady sings
Aug 14, 2002
4,697
40
seattle
^that looks hellish^

I remember the roll in on Hell Track was originally too steep/scary so they had to change it for the actual filming/movie. I forget what the numbers on it were though.....
 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
^that looks hellish^

I remember the roll in on Hell Track was originally too steep/scary so they had to change it for the actual filming/movie. I forget what the numbers on it were though.....
I was thinking the other day, maybe it wasn't so much the steepness that was the problem, it was the lack of a decent sized tranny at the bottom. If they had put a 14 foot radius quarterpipe at the bottom of that thing . . . .

 
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don

Turbo Monkey
Nov 8, 2001
1,321
0
Rumson, NJ
Hey cmc - I am working on a roll-in for a little pump/jump track in my backyard (I think this is version 5, haha). It can't be tall unfortunately as I don't want to piss off the neighbors. Deck will be 3' and then I dug 3' into the ground so 6' tall total. Also, I'd like my kids - ages 5 and up to be able to get in on it and not blow up. What would you think radius wise? I was thinking 10' and then round off the top with a reverse 5' but would love to hear what you think.

I'll throw some pics up as I get done with the deck to give a better idea what I'm working with.
 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
Hey cmc - I am working on a roll-in for a little pump/jump track in my backyard (I think this is version 5, haha). It can't be tall unfortunately as I don't want to piss off the neighbors. Deck will be 3' and then I dug 3' into the ground so 6' tall total. Also, I'd like my kids - ages 5 and up to be able to get in on it and not blow up. What would you think radius wise? I was thinking 10' and then round off the top with a reverse 5' but would love to hear what you think.

I'll throw some pics up as I get done with the deck to give a better idea what I'm working with.
yeah, post some pics.... i'd like to see what's coming after the roll-in. like, you dug 3 feet down, just under the roll-in.... or does the line continue for a while below ground level? (cuz if you dig a hole to gain momentum going downwards, you also use part of that momentum to get back up out of the hole).

here's another interesting roll-in on the left... don't know what you'd call it... maybe a "double down" ? it's hard to tell the dimensions, but the bottom half of the roll-in appears to be around 4'. the steepness looks about 45 degrees. on a short roll-in, i doubt you could go steeper than 45 degrees without it being squirrely.


An interesting question is how large should the top curve radius be for a bike roll-in versus a skate roll-in. The wheelbase of a skateboard is so short, compared to a bike.

Like, this design looks smoother . . . .


. . . than this design
 
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Paulyd

Monkey
May 15, 2007
255
0
Great White North.
I'm moving to a new house with my family, gunna live there for a month before I go away for university. I'm allowed to put in one jump, so I'm gunna make a wooden kicker, and a dirt landing, make a nice step up. One question though. What size roll in should i put in? out backyard is completely flat. Like there is no incline to it at all.
 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
I'm moving to a new house with my family, gunna live there for a month before I go away for university. I'm allowed to put in one jump, so I'm gunna make a wooden kicker, and a dirt landing, make a nice step up. One question though. What size roll in should i put in? out backyard is completely flat. Like there is no incline to it at all.
I think 12' tall at a minimum.

I know it's old, but it's the first thing that came to mind for an example . . . S&M BMX Inferno. http://bmxmdb.com/films/152-Bmx-Inferno Scroll down to the Neal Wood section. When he's riding the indoor park, notice he first rolls in on something that's about 8' tall, then has to crank a lot.... then he hits the vert wall and gets about 6-8' above a roughly 7 or 8' radius transition. From there, he jumps what looks like a typical 6' tall lip box jump and gets good height.
If you make your roll-in nice and steep, it will have a similar result.
 
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cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
My bro Abel's latest creation... It's built on the starting hill of what was a 4x practice track ... so i guess it's both a "roll-in" and a platform drop....



It takes one or two cranks rolling in to clear 12 feet to landing, followed by a 14 foot double. And it works...





Helltrack's hellish lack of tranny at the bottom of the 25 foot wall:



Chula Vista:



http://bmxmuseum.com/forums/viewtopic.php?id=39992&p=1
 
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don

Turbo Monkey
Nov 8, 2001
1,321
0
Rumson, NJ
i'm starting to think the platform-to-dirt-landing style is the best for 'trails' setup roll-in cuz that first landing kinda gets the flow going. . . .
Damn, those guys are getting some throttle off that setup. Doing a big set right off the bat. Pretty cool how they drop-in on a ramp to the platform and then drop off to the lander.

We have a roll-in/hill at our trails and just doesn't get it going well. Thinking a dirt "platform" to drop might be the ticket. Maybe a berm before it...

BTW, neat seeing Midget Cory and Aaron Bostrom in the clip.
 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
roll-in builder / trailboss Abel





video edit from recent jam:

http://vimeo.com/59382627
RBM Allied Compound Trip
from alex hammett


We took a trip to the Allied Compound in Manor, TX. Thanks to those guys for having us and letting us camp and ride. Thanks to Richardson Bike Mart for making this trip happen.

Riders- Mike Puyear, Joe Carroll, Joe Ladd, Ross Blanford, Landon Gideon, Mat Olson

Music- Dead Meadow- The Queen Of All Returns
 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
I took a trip to Steamboat Springs CO recently. There was DJ/Pump Track area under construction down in the town next to a small cement skatepark.

The roll-in for the jump area was really well done (although apparently they haven't finished the jump section). It seemed to be about 10-14 feet tall. The two-tier... waterfall-ish design was pretty cool.


View from top of roll-in:



The roll-in mound for the pump track, however, was not big enough (where the rider is sitting). Dropping in from 5 or 6 feet elevation does not give good speed to hit jumps, even small ones....

 
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cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin

"Abandoned "Giant Slide" at Coney Island, in May of 1973. (Arthur Tress/NARA) # "
 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
From Texas Toast 2013 this past weekend:

Railroad box car roll-in, once again. Room for a crank or two, little kicker, 11-ish foot tall roll-in; looks slightly steeper than 45 degrees; transition at the bottom.





 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
The rollercoaster thing has got me thinking. Maybe the Mega Ramp should use a parabolic roll-in, instead of a circular-tranny--flat-bank--circular-tranny like they have always done.

 

cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin


Highland MTB Park, NH



note how much taller the roll-in is that the first jump. (it's in the back of the pic and you can see the rider standing on it). you can't have a roll-in that is only 6 feet tall and expect for it to generate enough speed without cranking.
 
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cmc

Turbo Monkey
Nov 17, 2006
2,060
6
austin
This is a roll-in for a dirt jump line at Highland Bike Park. Note how the roll-in platform is much taller than the jump.