Bike / Buggy / KSR Frame Advice

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regionalchaos
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Bike / Buggy / KSR Frame Advice

Post by regionalchaos » Fri Sep 21, 2007 8:16 pm

Howdy folks,

Recently I've been scheming about building a 'quadricycle'.

http://en.wikipedia.org/wiki/Quadricycle

I think I'm pretty setup in my shop to handle the project, but I'm unsure of what size of metal I need to build the frame out of in order to be able to support the load I want to carry (4-5 people and a cooler full of goodies). I'm assuming there are some basic formulas I could use to figure it out? I was hoping you guys might be able to offer some advice or some links to information that might do me some good?

Thanks!

sun4all
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Here are some bike frame resources

Post by sun4all » Fri Sep 21, 2007 8:50 pm

This guy has an AMAZING site on bike building; here's the link to information on frames:

http://www.sheldonbrown.com/frame-materials.html

Nova Cycles supplies raw materials to frame builders. Seems like a great place to get frame material

http://www.novacycles.com/catalog/index.php

Atomic Zombie has all sorts of cool bike plans and I think they even have a book on bike building

http://www.atomiczombie.com

It seems like a lot of people make Playa bikes by chopping up two or more cheap used bikes.

Have fun!

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Elliot
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Post by Elliot » Fri Sep 21, 2007 9:26 pm

:D
:D
The term KSR caught my eye!

You are in Eugene, so you are thinking about the annual Kinetic Sculpture Race in Corvallis. Most years, there is even a one- or two-day workshop in Corvallis about building KSR Kontraptions.

I've built several Racing Skulptures, but I have never worried much about serious engineering. Maybe that's why my Machines are so danged heavy! Seriously, the dimensions of the materials are less important than the design. Stiffness and strength are mostly in large cross sections, like a roof truss in a house, and in triangulation -- also like a roof truss, now that I mention it.

Put an other way, you get the stiffness and the strength from the shape of the structure, rather than from the materials themselves. Imagine a sheet of plywood. Lay it flat between two saw horses, and stand in the middle of it. It will sag something awfully, yes. But set it on edge, and you can stand on the top edge without the plywood sagging at all. (Assuming you are really good at balancing :wink: )

A common problem in KSR is misalignment of chains and sprockets -- often caused by flexing of the frame. So think in terms of having every chain solidly supported by a triangular structure as close to the chain as possible. This means keeping sprockets close to bearings -- not out on a long free end of a shaft.

If you are new to this sort of fabrication, then bicycles are indeed a good way to start out. Round up some thrift store bikes, and cut and weld until it looks right.

Does this help?

Oh... there is a Kinetic Sculpture Race in Port Townsend, Washington (near Seattle, out on the Olympic Peninsula) October 6 - 7 -- if you want to look at 20+ kool Kinetic Kreations.
:D

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regionalchaos
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Post by regionalchaos » Fri Sep 21, 2007 10:15 pm

Elliot I added the KSR just to catch your eye ;P

I think I'll start with a 2 seater, and leave an open space behind to add more later, just to get the design down. I guess I just tend to approach things from a technical manner, and all the material I find just says, "Grab some metal and go!". I did some reading on line and recently picked up the atomic zombie book.

I'd like to be able to have it support 4-5 people, so I know that is going to be around 1000lbs or so. It makes me want to know for sure that the frame I build can hold it. And since it will be petal powered to start with (I want to add motor assist though), I'd like it as light as possible. I just want to make sure I don't go too light!

Thanks for the info Elliot, its helpful.

And thanks for the other links above.
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Elliot
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Post by Elliot » Sat Sep 22, 2007 9:47 am

:D
Even if you are not going across open water, you may find something useful on my How To Build A Kinetic Racer page:

http://kinetickingdom.com/KK-how2/index.html

:D

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regionalchaos
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Post by regionalchaos » Sat Sep 22, 2007 12:14 pm

Great Info Elliot!

The stuff about the types of chain to use were especially informative. I hadn't heard of #40 chain before, but it makes sense and sounds like something I would want to use. If normal bike chain will skip and jump and derail more frequently, I'd rather not have to worry about it on the playa.
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