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Don't skid
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Interesting article on the stability of the bicycle in the Sept. 2006 issue of Physics Today. Its called "The stability of the bicycle" written in 1970 by David E. H. Jones.
The guy bascially asks what makes bikes stable and the try to create and unrideable bike to test his theories. Its old school though.

Unfortunately you need a subscription to read it but if your in college most schools should have one.
 

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KONA_in_SB said:
Interesting article on the stability of the bicycle in the Sept. 2006 issue of Physics Today. Its called "The stability of the bicycle" written in 1970 by David E. H. Jones.
The guy bascially asks what makes bikes stable and the try to create and unrideable bike to test his theories. Its old school though.

Unfortunately you need a subscription to read it but if your in college most schools should have one.
Since you bring it up you could scan a copy and post it for the rest of us (otherwise you are just teasing us...that's dirty mmmm'K)?? :skep:
 

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Don't skid
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miSSionary said:
Since you bring it up you could scan a copy and post it for the rest of us (otherwise you are just teasing us...that's dirty mmmm'K)?? :skep:
I thought about that but wouldn't that be against MTBR rules, distrubuting copyrighted material?
 

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KONA_in_SB said:
I thought about that but wouldn't that be against MTBR rules, distrubuting copyrighted material?
Naaa, post it so we know what you are talking about!! Come on Come on PLEASE?? POST IT POST IT NOW!! Everyone's posting things these days....post it post it!! :thumbsup:
 

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conjoinicorned
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i have a .pdf of that article, is there a way i can post the .pdf file? it's not the best quality scan so i don't think it will lend itself to .jpg very well.
 

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ZoSoSwiM said:
he lost me on page 3... haha. I'm no physics guy though so oh well.
Ha ha ha, I am lost to, time to re-read...thanks guys for posting the article!! :D
 

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Out there
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fascinating article, thank you for posting!

his conclusions are really interesting

-- at high speeds, the gyroscopic effect of the wheels is important in keeping a bike upright

-- at low speeds the gyroscopic effect of the wheels is unimportant

-- you can make a bike inherently much more stable by reversing the front forks. This makes the bike self-steer, so that as it tips over one way the wheel turns automatically to correct it

-- however, a bike which is more stable (in this sense) is actually much more difficult to ride.

I loved the idea of him trying to build unrideable bicycles. My favorite was the one which had a furniture castor for the front wheel.
 

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The Dude Abides
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It's the same idea behind fighter jets being purposfuly designed to be aerodynamicaly very unstable.

Although the pilot does fly the plane, the plane has to have computers running many programs behind the scenes to keep the plane on an even keel, but it also makes them very manuverable in the air.
 

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Hoops - Big and Small
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Class is in session

theeric said:
It's the same idea behind fighter jets being purposfuly designed to be aerodynamicaly very unstable.
What do ground effects and wind effects have in common?

More of a theoretical question rather the a law of physics question.
 

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mtnjam
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great article!

Thanks for posting that C_B.....where did you end up finding that .pdf?

Great reading for someone with or without a physics/engineering background. Didn't seem too complex of a read for me, but then again I've read Chaos, The Fourth Dimension, The Tao of Physics, Broca's Brain, Q.E.D. : The Strange Theory of Light and Matter....

Kind of interesting I ran across this article as I was just reading in Bike magazine about the rotational physics of bearings
 

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Hoops - Big and Small
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Google Find

Man I wish I could remember what I did even yesterday - The unrideable bike concept (can't remeber where I read about it :madman: ) appealed to my curiosty. Reminded me of the day when I would hack together different bikes, motorcycles and go-carts to see how things work.
 

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not a whole lot

Crash_Burn said:
What do ground effects and wind effects have in common?

More of a theoretical question rather the a law of physics question.
Not a whole lot!

Ground effect per aviation refers to additional lift created by a wing that is close to the ground. This has to do with trapping air under the wing that would normally spill out at the tips creating vorticies. This effect causes additional lift. People have died due to overloading aircraft, taking off, and then being unable to lift off more than a few feet above the runway, in other words lifting off out of ground effect.

The Russians built huge assault vehicles using ground effect-google 'ekranoplan'-one is way bigger than a 747 and flies about 20 feet above the sea.

Ground effect in cars really only works at crazy speeds; kids and their cars with wings and air dams make me seriously laugh.

The wings on indy and f1 are basically upside down airfoils. Airdams on stock cars eliminate airflow under the car which causes drag.

I'm not sure of which is which, but some open wheeled cars are required to have smooth bottoms to eliminate ground effects while others like f1 utilize areodynamics underneath to create a partial vacuum, holding the car tighter to the ground.

All of the other little winglets, etc., you see on open wheelers are there to smooth airflow over the tires, through the rads, and to control airflow across the front and rear wings.

Drew
 
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