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> Bicycle Balancing, gyroscope explanation
boit
Posted: Dec 15 2009, 09:22 PM


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I have heard that a bicycle travels true due to the gyroscope effect generated by its wheels. Can it be experimentally demonstrated by say riding a bike on a long conveyor belt (or a tread mill). Somebody please try. unsure.gif


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Boit was last taught physics in class way back in 1994. Whatever he's learnt thereafter is purely by personal effort through this forum and searching the net. He is not an authority in any matter science. Unless with clear referrence, what he puts forward is his own understanding of what he has read and may not always be correct. Peace.
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flyingbuttressman
Posted: Dec 15 2009, 10:03 PM


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QUOTE (boit @ Dec 15 2009, 04:22 PM)
I have heard that a bicycle travels true due to the gyroscope effect generated by its wheels. Can it be experimentally demonstrated by say riding a bike on a long conveyor belt (or a tread mill). Somebody please try. unsure.gif

Are you freaking serious?

I'm going to venture that you have been to high school science class. Did your science teacher by any chance have a bicycle wheel with a handle attached? If not, you were in a shitty science class. The bicycle wheel is used to demonstrate a spinning object's resistance to changes in orientation.

Go, buy a gyroscope and test it yourself.


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prometheus
Posted: Dec 15 2009, 10:11 PM


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H2O
Posted: Dec 16 2009, 04:18 AM


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Simply yes. The bike doesn't have to be physically moving forward. The wheels just merely have to be spinning. I believe it has to do with the conservation of angular momentum.


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Kelkoshoz
Posted: Dec 16 2009, 08:00 AM


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QUOTE
I believe it has to do with the conservation of angular momentum.

This is applicable when a bycicle moves with a considerably high speed, when the wheels spin fast, but if it moves slowly the conservation of angular momentum contributes much less to the balancing. There's another mechanism that comes to the scene.
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H2O
Posted: Dec 16 2009, 01:03 PM


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Do some experiments with two or three gyros...I have found that the two largest factors are the mass of the gyro and speed of rotation. This is consistent with the equation..

L = r x mv

The slower you go on a bike the harder it is to stay up right. This is most noticeable if you don't use your hands.


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I have received no formal education in much of the subject matter on this forum and have only a high school diploma. What I do know (that would be beyond high school) is what I have learned over the years from reading books, magazines, blogs, forum posts etc. or have seen in documentaries, short clips, etc.

The opinions in my post are my own and do not reflect anyone else's unless referenced and may not be correct.
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boit
Posted: Dec 16 2009, 05:18 PM


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QUOTE (flyingbuttressman @ Dec 15 2009, 10:03 PM)
Are you freaking serious

Obviously your mama (or your gay parents) never taught you good manners . You are not obliged to answer if you don't want to. I was in a science class. I will donate wheels and all now that I can afford them. I don't dispute that a bike is easily balanced in motion. I just lack the materials to demonstrate if this gyroscope explanation is all that is needed or experience (practice) in riding plays a bigger role.

What is the purpose of all this you may ask? Imagine stopping at the traffic lights and you are achondroplastic (short limbs). An attached gyroscope will come in handy. I don't want to invest in one to be disappointed later. So can it work. How massive should it be say to support a 60 kg rider? Let others answer. You are excused.


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Boit was last taught physics in class way back in 1994. Whatever he's learnt thereafter is purely by personal effort through this forum and searching the net. He is not an authority in any matter science. Unless with clear referrence, what he puts forward is his own understanding of what he has read and may not always be correct. Peace.
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flyingbuttressman
Posted: Dec 16 2009, 05:37 PM


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QUOTE (boit @ Dec 16 2009, 12:18 PM)
What is the purpose of all this you may ask? Imagine stopping at the traffic lights and you are achondroplastic (short limbs). An attached gyroscope will come in handy. I don't want to invest in one to be disappointed later. So can it work. How massive should it be say to support a 60 kg rider? Let others answer.

Training wheels.


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boit
Posted: Dec 16 2009, 06:47 PM


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QUOTE (flyingbuttressman @ Dec 16 2009, 05:37 PM)
Training wheels.

First. Thanks to Prometheus for that link "Tru Trainer rollers". Secondly thanks to you for being prompt and civil. Chastise me too if I deviate from proper language now or in future. Trainer wheel have their limitation like when riding on a footpath for example (shrubs on the sides).
For the gyro option, should it be as heavy as the bicycle wheel(s). Does size matter? I cant get far with 'pseudo thought experiment' neither do I have access to computer sumulation. Who can help. I am ready to supply a diagram of what I have in mind.


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Boit was last taught physics in class way back in 1994. Whatever he's learnt thereafter is purely by personal effort through this forum and searching the net. He is not an authority in any matter science. Unless with clear referrence, what he puts forward is his own understanding of what he has read and may not always be correct. Peace.
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flyingbuttressman
Posted: Dec 16 2009, 06:52 PM


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QUOTE (boit @ Dec 16 2009, 01:47 PM)
First. Thanks to Prometheus for that link "Tru Trainer rollers". Secondly thanks to you for being prompt and civil. Chastise me too if I deviate from proper language now or in future. Trainer wheel have their limitation like when riding on a footpath for example (shrubs on the sides).
For the gyro option, should it be as heavy as the bicycle wheel(s). Does size matter? I cant get far with 'pseudo thought experiment' neither do I have access to computer sumulation. Who can help. I am ready to supply a diagram of what I have in mind.

One thing you could do is add "spinners" to the tires. These would be equal to or greater than the mass of the tires, and would look like disks with almost the same radius as the tire. They would have a ratchet mechanism that would let them spin independently of the tires, but would allow them to gain angular momentum when the bicycle is in motion. With 4 of such devices (1 on each side of each tire), you might be able to stay upright when stopped until the spinners slow down.

Edit:
http://www.engadget.com/2006/04/28/gyrobik...es-self-steady/

This post has been edited by flyingbuttressman on Dec 16 2009, 06:57 PM


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boit
Posted: Dec 16 2009, 08:14 PM


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QUOTE (flyingbuttressman @ Dec 16 2009, 06:52 PM)
They would have a ratchet mechanism that would let them spin independently of the tires, but would allow them to gain angular momentum when the bicycle is in motion. With 4 of such devices (1 on each side of each tire), you might be able to stay upright when stopped.

I'll add a mechanism to continue turning them spinners by back-peddling. Great how you read my mind. Good gracious! One wouldn't be in danger of wasting a lifetime re-inventing the wheel (no pun intended) with you guys nearby to guide us through. Thanks alto for that link. A gyro bike! Am vindicated my idea wasn't out of the mainstream thought. People have been labled cranks for less.

Finally, could the admin edit the first line of my earliest post but one or delete it entirely. I was totally unfair to you. Sorry. Thanks alot for your dedication.


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Boit was last taught physics in class way back in 1994. Whatever he's learnt thereafter is purely by personal effort through this forum and searching the net. He is not an authority in any matter science. Unless with clear referrence, what he puts forward is his own understanding of what he has read and may not always be correct. Peace.
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flyingbuttressman
Posted: Dec 16 2009, 09:08 PM


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No worries.


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- Isaac Asimov

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Confused2
Posted: Dec 16 2009, 09:36 PM


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orestis
Posted: Dec 16 2009, 09:37 PM


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QUOTE (boit @ Dec 16 2009, 01:18 PM)

What is the purpose of all this you may ask? Imagine stopping at the traffic lights and you are achondroplastic (short limbs). An attached gyroscope will come in handy. I don't want to invest in one to be disappointed later. So can it work. How massive should it be say to support a 60 kg rider?

If you already ride a bike you know that when pedaling the frame of the bike goes from one side to the other. Especially when you want to apply power. A gyro might screw that up. On top of the extra weight you would have to carry.

Having a bike built to scale might be a cheaper and better idea.


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Enthalpy
Posted: Jan 30 2010, 11:32 PM


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I believe gyroscopic effect does give stability to bicycles, because:
- If riding fast enough without holding the handlebar, you don"t need active corrections to stay stable;
- A bicycle can ride downhill and stay stable without a rider.

However, some other effects could give passive stability. For instance, that the front wheel is before the handlebar's axis. Or that the tire has a width and a round form.

One easy experiment is to turn the front wheel when holding the bicycle at its frame, and incline the frame: observe the wheel's reaction.

Notice that I don't care too much what was told at school, since so little was sensible there.

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"A big gyroscope" and "opposing changes of orientation": not really.

Because a gyro does NOT oppose an intent to change its orientation. It reacts with a strong moment, which is perpendicular to the change you intend, not opposed to it.

So the normal reaction of a gyroscope is complicated (it uses to swirl then) and little usable.
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