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Old 09-02-2013, 06:00 PM   #976
lnewqban
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Quote:
Originally Posted by dazeedmonds View Post
...........The gyroscopic action of the wheels does help balance the motorcycle, however the same gyroscopic properties are WHY counter steering works.
.................
Try this: In a SAFE place initiate a lean by counter steering. Then release all input in the direction of the lean, unless you are far enough over that the camber of the tires will carry you through the turn, the bike will right itself. You actually have to continually apply the same amount of pressure throughout the duration of the turn to maintain the turn. That is the gyroscopic action at work.
Because it is an acceleration, the gyroscopic reaction of the front wheel helps leaning the bike, yes, but only while the handlebar is being turned.
It also depends on the rotational speed and mass of the wheel-tire.

Even when you stop the turning of the handlebar, the bike may continue falling into a lean.
The reason is that centripetal acceleration is another force inducing that lean.
As long as both tires are aligned to turn and describing a circular movement, that centripetal acceleration is present (stronger for higher speed and lower radius).

The bike reaction that you describe is proper of under-steering bikes.
Depending on tires' profiles and steering geometry there are also neutral and over-steering bikes when turning.
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Old 09-02-2013, 06:33 PM   #977
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Quote:
Originally Posted by lnewqban View Post
Because it is an acceleration, the gyroscopic reaction of the front wheel helps leaning the bike, yes, but only while the handlebar is being turned.
It also depends on the rotational speed and mass of the wheel-tire.

Even when you stop the turning of the handlebar, the bike may continue falling into a lean.
The reason is that centripetal acceleration is another force inducing that lean.
As long as both tires are aligned to turn and describing a circular movement, that centripetal acceleration is present (stronger for higher speed and lower radius).

The bike reaction that you describe is proper of under-steering bikes.
Depending on tires' profiles and steering geometry there are also neutral and over-steering bikes when turning.

Correct, that is what I said. Release the handlebar and the bike will right itself, UNLESS you have pushed the bike far enough over that other forces will guide the bike and continue the lean. Perhaps I did not make my previous post clear enough. I was only stating that that the gyroscopic action of the wheel causes the bike to begin the turn. There are many different forces at work when turning a bike.

I was merely rebutting joexr's opinion that the gyroscopic forces only keep the bike upright; which is incorrect. Gyroscopic principles also (and perhaps I should have said it this way to begin with) BEGIN the turning process.


ALL of this however is not relevant to helping a new rider learn about counter steering. I was simply saying that showing a n00b how turning a gyro will cause it to lean, may be helpful (if an over-simplification of the process) in explaining counter steering.
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Old 09-02-2013, 06:48 PM   #978
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Nope, the out steering of the contact patches starts the lean. The gyroscopic force that the front wheel exerts on the bike by turning the handlebars is much less than that of the moving contact patches. So much less that it's force can be considered zero.

It is equivalent to the force of your input into the bars. Which is why the bars get harder to turn the faster you go, but is not enough force, for instance, to pick the bike up from a 30 degree lean.
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Old 09-02-2013, 07:00 PM   #979
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Quote:
Originally Posted by Boon Booni View Post
Nope, the out steering of the contact patches starts the lean. The gyroscopic force that the front wheel exerts on the bike by turning the handlebars is much less than that of the moving contact patches. So much less that it's force can be considered zero.

It is equivalent to the force of your input into the bars. Which is why the bars get harder to turn the faster you go, but is not enough force, for instance, to pick the bike up from a 30 degree lean.
In search of knowledge I ask: Why then do I press on the left handlebar to pull the bike out of a right handed turn?

(seriously asking, accepting the possibility that I may be wrong)
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Old 09-02-2013, 07:04 PM   #980
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Quote:
Originally Posted by dazeedmonds View Post
In search of knowledge I ask: Why then do I press on the left handlebar to pull the bike out of a right handed turn?

(seriously asking, accepting the possibility that I may be wrong)
COUNTERSTEERING.
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Old 09-02-2013, 07:07 PM   #981
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Quote:
Originally Posted by dazeedmonds View Post
In search of knowledge I ask: Why then do I press on the left handlebar to pull the bike out of a right handed turn?

(seriously asking, accepting the possibility that I may be wrong)
To turn more sharply and bring the contact patch back under the bike.
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Old 09-02-2013, 07:12 PM   #982
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Thanks!

The info on the website is great. I have been riding about 2 years now, but I just hit 8,000 miles on my bike today. I am always looking to learn to be a better rider!

Quote:
Originally Posted by Center-stand View Post
..

Well, maybe we can't figure out how we get our bikes through the twisties, but we sure can make this thread go in circles.

Here, again, is a link I posted 10 or 11 pages back.

http://www.manicsalamander.com/artic...cycle-(!).aspx

..
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Old 09-02-2013, 07:16 PM   #983
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Quote:
Originally Posted by Boon Booni View Post
To turn more sharply and bring the contact patch back under the bike.
So to make sure I understand (things are a bit fuzzy but I think I get what you are saying) In making a Right turn we turn the wheel to the left, by pressing on the Right handlebar, this makes the bike fall over to the right because it has been unbalanced, during the turn the wheel moves back to the right to guide us through the turn, at the end of the turn we push left, moving the front wheel farther to the right, and this moves the contact patch Left (?) closer to the center line of the bike and this pulls the bike upright?
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Old 09-02-2013, 07:22 PM   #984
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Quote:
Originally Posted by dazeedmonds View Post
So to make sure I understand (things are a bit fuzzy but I think I get what you are saying) In making a Right turn we turn the wheel to the left, by pressing on the Right handlebar, this makes the bike fall over to the right because it has been unbalanced, during the turn the wheel moves back to the right to guide us through the turn, at the end of the turn we push left, moving the front wheel farther to the right, and this moves the contact patch right closer to the center line of the bike and this pulls the bike upright?
Basically, a steady state turn is a balance of centrepidal force (standing the bike up) and gravity (pulling the bike down). To stand up you steer sharper into the turn so that centrepidal force over comes gravity and stands the bike up.
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Old 09-02-2013, 07:29 PM   #985
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Quote:
Originally Posted by Boon Booni View Post
Basically, a steady state turn is a balance of centrepidal force (standing the bike up) and gravity (pulling the bike down). To stand up you steer sharper into the turn so that centrepidal force over comes gravity and stands the bike up.
Ok. I follow.

so moving the contact patch right, moves the contact patch closer to the center line of the bike?

Does that mean that the front wheel has been to the left of the center line throughout the turn?

Or are we just giving in to centripetal force and allowing it to pull the bike up?

Or is my physics broken?
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Old 09-02-2013, 07:43 PM   #986
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Quote:
Originally Posted by dazeedmonds View Post
Ok. I follow.

so moving the contact patch right, moves the contact patch closer to the center line of the bike?

Does that mean that the front wheel has been to the left of the center line throughout the turn?

Or are we just giving in to centripetal force and allowing it to pull the bike up?

Or is my physics broken?
You controll centrepidal force with the the front wheel. You use it to balance gravity in a steady state turn, and to overcome gravity to stand the bike up.

I'd post a diagram if I wasn't posting from a tablet at the moment.
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Old 09-02-2013, 07:45 PM   #987
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Quote:
Originally Posted by dazeedmonds View Post
...............during the turn the wheel moves back to the right to guide us through the turn, at the end of the turn we push left, moving the front wheel farther to the right, and this moves the contact patch Left (?) closer to the center line of the bike and this pulls the bike upright?
Please, forget about this confusing part: "this moves the contact patch Left closer to the center line of the bike".

Pushing forward on the left (or right) hand-grip induces forces that roll the bike over to the left (or right) side.
That happens either you start up from a vertical position or from a right lean.

Furthermore, in order to stop that roll over, precisely at the balance position (vertical or leaned), we briefly countersteer in the opposite direction (like an imperceptible but quick braking burst).
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Old 09-02-2013, 07:55 PM   #988
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Quote:
Originally Posted by lnewqban View Post
Please, forget about this confusing part: "this moves the contact patch Left closer to the center line of the bike".

Pushing forward on the left (or right) hand-grip induces forces that roll the bike over to the left (or right) side.
That happens either you start up from a vertical position or from a right lean.

Furthermore, in order to stop that roll over, precisely at the balance position (vertical or leaned), we briefly countersteer in the opposite direction (like an imperceptible but quick braking burst).
Yeah, I get that. I'm simply interested in the physics of why it occurs. A mental exercise if you will. What specifically brings the bike upright again. I thought it was gyroscopic precession, but that is apparently not the case.

The front wheel is fighting against gravity, and by turning the front wheel we either succumb to gravity (to initiate the turn) or resist gravity (to right the bike after the turn)
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Old 09-02-2013, 08:07 PM   #989
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Quote:
Originally Posted by dazeedmonds View Post
Yeah, I get that. I'm simply interested in the physics of why it occurs. A mental exercise if you will. What specifically brings the bike upright again. I thought it was gyroscopic precession, but that is apparently not the case.

The front wheel is fighting against gravity, and by turning the front wheel we either succumb to gravity (to initiate the turn) or resist gravity (to right the bike after the turn)
The simplest apology is balancing a broom stick on your finger. If you want to move the broom stick the the the right you have to first move your finger to the left to make the broom stick fall toward the right. Once it starts falling to the right you have to move your finger to the right to maintain a constant lean. When you want to stop moving to the right you have to move your finger even faster to the right in order to get back to vertical.
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Old 09-02-2013, 09:04 PM   #990
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Quote:
Originally Posted by dazeedmonds View Post
........The front wheel is fighting against gravity, and by turning the front wheel we either succumb to gravity (to initiate the turn) or resist gravity (to right the bike after the turn)
Not exactly.

While we roll over a straight line, the weight vector starts at the CG (combined rider+bike) and points vertically down and aligned with our support points: the contact patches.
We are in vertical balance.

As soon as we deviate from a straight line trajectory, the vector weight tilts from the CG toward the outside of the turn or curvilinear trajectory.
The faster we roll and the smaller is the radius of the circular trajectory, the bigger is the angle of deviation from vertical of that vector.
We people like complicating things, so we decompose that vector into weight and centrifugal force, but in reality that tilted vector is the actual force that the bike feels.
Suddenly, we are out of balance and our contact patches are not aligned with that vector.
We need to roll over the bike in order to re-gain that comfortable balance.
..............but how can we?



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