Author Topic: Light weight roll cage for street motorcycle streamliner  (Read 16231 times)

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Offline 4stroke

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Light weight roll cage for street motorcycle streamliner
« on: June 13, 2015, 11:52:50 PM »
Hello I am trying to learn how to design an effective light weight roll cage for road use.  Can you direct me to a good resource with information regarding how much of a buffer should I use around my body and head, how much protection for front and rear end collision with car/tree.  Straight vs curved tubing.  Minimum tube thickness and diameter to keep weight low.

I have heard that Buddfab 50cc streamliner is 725lb with driver and Baumm NSU Streamliner is 2171bs without the engine this is too heavy/slow for street driving.

Without suicidal ejection (been there not fun) like conventional motorcycle I need the cage to protect me from:

Low slide up to 110kph
High slide up to 110kph
Rolling at 110kph
Car rear ending me at traffic lights at 70kph
Front end car pulling out in front of me/tree at 70kph

Also need to be able to

Lane filter
Use motorcycle parking (max 280cm)
Maneuver car parks
Put the foot down at traffic lights
See the road ahead of me

I hope you can direct me to relevant information so I can design an effective build-able design for an engineer to certify.

I am also tossing up the idea of using 125cc engine but I need to figure out what the whole bike will weigh then I'll know what engine will be suitable.

Offline Peter Jack

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #1 on: June 14, 2015, 12:18:20 AM »
You're looking for the impossible, especially when you're looking for an engineer to put his stamp on such a design. Those of us involved in racing know that no matter what the design there is risk involved whenever you get in a race vehicle.

Good luck. I think you're chasing the impossible dream.

Pete

Offline kiwi belly tank

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #2 on: June 14, 2015, 01:52:37 AM »
There are race vehicles that just don't transfer to being streetable, now that you've brought it up, a bike liner would probably number 1 on that list. You should really spend some time conversing with the logic side of your brain on this one.
  Sid.

Offline sofadriver

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #3 on: June 14, 2015, 02:02:28 AM »
You should really spend some time conversing with the logic side of your brain on this one.
  Sid.

 Awesome! :cheers: :cheers: :cheers:



seriously, 4stroke ........... buy a car
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Offline WhizzbangK.C.

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #4 on: June 14, 2015, 02:07:38 AM »
http://blog.hemmings.com/index.php/2013/12/12/cars-of-futures-past-peraves-ecomobile-monotracer/

It's been done, with some success, even limited mass production. Never could get to critical mass to sustain itself though.
Ah, this is obviously some strange usage of the word 'safe' that I wasn't previously aware of.  Douglas Adams

Offline Stainless1

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #5 on: June 14, 2015, 09:33:19 AM »


I have heard that Buddfab 50cc streamliner is 725lb with driver and Baumm NSU Streamliner is 2171bs without the engine this is too heavy/slow for street driving.


I am also tossing up the idea of using 125cc engine but I need to figure out what the whole bike will weigh then I'll know what engine will be suitable.
How heavy and fast is you current bike...  :evil:  :dhorse:
« Last Edit: June 14, 2015, 09:35:10 AM by Stainless1 »
Stainless
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Offline Eric_Noyes

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #6 on: June 14, 2015, 06:36:47 PM »
The Buddfab weighs about 575 with driver. Years ago I gave an incorrect number during a hot afternoon Bonneville interview and it has been repeated often.

Offline JimL

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #7 on: June 14, 2015, 08:00:24 PM »
Interesting memories from your ideas:  Snap open, rearward sliding lower doors was the best system tried during some study done about 30-35 years ago.  The doors had to be "open" above hip level when the rider pushed the thumb release lever.  Test riders felt this would be dangerous in a simple low speed fall.  At that time, the mechanism was spring loaded with a long lever to pull them shut.

Another problem found during testing, I was told, was rapid front tire wear under almost all riding conditions and very difficult brake control.  I never got to see any of this stuff, but was contacted to discuss ABS methods for a possible sidecar type adaptation.  The language difficulties made our discussions complicated, but I know the sidecar type design became a dead end.  Keep in mind, this was all many years before the advent of modern VSC, multi-channel integrated ABS, and computer controlled electronic power steering systems.

Across the other ocean, Honda did some really good work on motorcycle design safety and found the best solution is to eject the rider cleanly with as little injury as possible during the actual impact/rider ejection event.  The production result was the PC800, which you can still find good ones on the used market. 

If you find one, you should fabricate a short handle, large Hex head tool to replace the O-rings on the sides of the cylinder heads.  The fully enclosed engine tends to cook seals and O-rings on these bikes, which means you can often buy one cheap due to the oil leaks.  That was how I got mine, many years ago.  Don't have the bike, anymore, but still have the tool if you need to use it!  Wonderful bike, by the way, and incredible gas mileage for something that can cruise so fast (but they eat front tires).

Physics is against you on this idea, and there has been some pretty big money spent to prove that fact.

JimL 

Offline 4stroke

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #8 on: June 14, 2015, 08:35:18 PM »
Interesting reply JimL.

Here is how I see it.

Cars are too big, heavy, slow, have too many wheels, drink too much fuel and cost too much to own and run.  They can't filter, they can't use motorcycle parking, I cannot put my foot down at lights in a car and I only ride motorcycles.  Plus motorcycles are cool.

Motorcycles have too much frontal area, aerodynamic drag, fuel consumption and they are unnecessarily dangerous (low slide, high slide).

I want a combination of the two to create an optimal vehicle to meet my needs.  Minimal frontal area, minimal aerodynamic drag, remarkable fuel consumption and reduced danger during low slides, high slide and rolls.  I think it is a great idea.

487.883lb is my combined vehicle weight.
575lb with driver sounds pretty good for Buddfab 50cc.

Can anyone direct me to roll cage building resource?  It seems the internet is saturated with roll cages for cars.

I am thinking of using mid engine design, the following fellow was able to build his bike weighing less than the original but it does not have roll cage resulting in his injury.
http://rohorn.blogspot.com.au/
« Last Edit: June 14, 2015, 08:36:57 PM by 4stroke »

Offline RichFox

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #9 on: June 14, 2015, 10:10:03 PM »
I don't know anything about a roll cage building resource. I think your best bet it to attend a LSR event and look at what's there. No two will be alike. You could talk to the builder of the Bub Fab bike and others for their thoughts.

Offline 4stroke

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #10 on: June 14, 2015, 10:22:05 PM »
I don't know anything about a roll cage building resource. I think your best bet it to attend a LSR event and look at what's there. No two will be alike. You could talk to the builder of the Bub Fab bike and others for their thoughts.

I was thinking there would be certain rules like they have for F1 cars and dragster roll cages.  I remember reading one build thread about how the roll bar protecting the head had to have minimum space to prevent head and spinal injuries if you hit the roof.  That would be good information to have.

There is lsr in Australia I have sent an email regarding roll cage information.

Offline RichFox

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #11 on: June 14, 2015, 11:03:27 PM »
Are you in Australia? Then yes, I would think a DRLA rule book might have the cage requirements to compete at their event. As does the SCTA rule book here. But it is a long way from a blueprint for building a cage.

Offline sockjohn

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #12 on: June 14, 2015, 11:17:54 PM »
One other thing to keep in mind is once you are strapped in with a harness you really need to be thinking head and neck restraint.

A three wheel vehicle despite the other drawbacks and failing to meet your other criteria is pretty much the better solution

Offline Milwaukee Midget

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #13 on: June 15, 2015, 01:45:08 AM »

. . . Can you direct me to a good resource with information regarding how much of a buffer should I use around my body and head, how much protection for front and rear end collision with car/tree . . .

I can't begin to imagine how much protection one would need on a motorcycle if a tree collided with it from behind.

Without suicidal ejection (been there not fun) like conventional motorcycle I need the cage to protect me from:

Low slide up to 110kph
High slide up to 110kph
Rolling at 110kph
Car rear ending me at traffic lights at 70kph
Front end car pulling out in front of me/tree at 70kph

Also need to be able to

Lane filter
Use motorcycle parking (max 280cm)
Maneuver car parks
Put the foot down at traffic lights
See the road ahead of me


You have many needs.

For a street driven motorcycle, I think your parameters are unrealistic.

Have you considered a decent helmet and leathers, or possibly a course in defensive driving techniques?

Okay, I am being a jerk.  But you're looking to build a lightweight cocoon on 2 wheels with survivability against calamities few cars weighing 8 times more than what your proposing are expected to survive.

That's a tough need to fulfill.

Chris

"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline Milwaukee Midget

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Re: Light weight roll cage for street motorcycle streamliner
« Reply #14 on: June 15, 2015, 02:39:54 AM »
Seriously, let me illustrate my point.

Here's a series of vehicles hitting a short wall at 40 mph, which translates to 64 kph -

https://www.youtube.com/watch?v=zk5cp93zefk

Upon collision, the bike and rider will go from 0 to 64 kph virtually instantaneously, and the car will continue it's forward progress.

You'd likely be looking at about an 18 G impact.  Might be survivable, but for a vehicle less than 10 feet long to absorb collisions like this with a human being aboard, you'd be hard pressed to find materials that would be as light as you propose.




"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll: