Gyroscopic Effect

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Racer, WOW! 85% I wouldn't have guessed more than 50% and I wouldn't have bet on that.

Acebobby, I believe when racer was talking about wheel base he meant wheel track. At least that's how I read it. That is why they call a bike a "single track vehicle".

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Ah, wheeltrack. Thanks. I assumed that the word "narrow" would provide a clue in that context.

and as a pre warning I am not a scientist, I am entering a discussion, not an arguement!

If it takes 1 tenth of a secnd for an object to fall 1 metre, if gravity pulls the bike down, wouldn't it be possible to steer your bike to the desired lean angle in less than 0.1 of a second, can anyone steer this fast? Say from upright to 45 degrees probably a distance of less than half a metre. Take a sportsbike, at 20 mph it is easy to steer to 45 degrees but what about when you go faster say 60 mph, does it require more effort to turn? what kind of effort does it need? is it push the bars harder? or push the bars faster? or both?

Agreed. Discussion, not argument.

And I tend to agree with your conclusion. My personal belief is that this is because the bike is rotating. Not falling. So, there is a horizontal component of motion (or vector) as well as vertical. Hence, we cannot merely consider the vertical force, gravity, alone.

I'm actually at work and sneaking off to read this. I have to bolt before my boss catches me being bad.

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I have to disagree with you on the "because of gravity" there is friction point. The friction that we need in any land based vehicle is rolling friction and is an OPPOSING FORCE. It is this opposing force that gives us traction.

I understand your analogy regarding moment and center of gravity and I think you're onto something with explaining one of the forces involved in countersteering initiating the lean angle.

Let us keep in mind that gravity is not a force that necessarily is downward. Once lean has been established it is gravity that keeps us from falling over by application of throttle and is also why the suspension compresses and causes the bike to loose further ground clearance.

Lastly,

Just because you lost us in your explanation doesn't mean that we can't speak the kinematic language.

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I have to disagree with you on the "because of gravity" there is friction point. The friction that we need in any land based vehicle is rolling friction and is an OPPOSING FORCE. It is this opposing force that gives us traction.

Um... okay. What do you think causes friction at the contact patch of a motorcycle driving in a straight line, Jay?

I understand your analogy regarding moment and center of gravity and I think you're onto something with explaining one of the forces involved in countersteering initiating the lean angle.

Cool. You are the first person to say you understood my analogy. Thanks.

So, what other force(s) do you think are involved?

Let us keep in mind that gravity is not a force that necessarily is downward.

Erm... really? In what other direction does gravity act here on planet Earth?

Once lean has been established it is gravity that keeps us from falling over by application of throttle and is also why the suspension compresses and causes the bike to loose further ground clearance.

With all due respect, Jay, I think you might be mixing gravity up with some other force(s). Here is a link to an excellent online website for Physics and Kinematics (presented in plain English) that I found very helpful.

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I am entering a discussion, not an arguement!

If it takes 1 tenth of a secnd for an object to fall 1 metre, if gravity pulls the bike down, wouldn't it be possible to steer your bike to the desired lean angle in less than 0.1 of a second, can anyone steer this fast? Say from upright to 45 degrees probably a distance of less than half a metre. Take a sportsbike, at 20 mph it is easy to steer to 45 degrees but what about when you go faster say 60 mph, does it require more effort to turn? what kind of effort does it need? is it push the bars harder? or push the bars faster? or both?

You know, I think you might really be onto something here, Bobby. Not only about the time it takes to lean the bike, but, also the difference at different road speeds. This is what I was thinking about today while communing with a 600RR and meditating on Will's leverage angles. The amount of force and leverage it takes to turn the front wheel increases greatly with speed. Partly due to the increase in resistance of gyroscopic forces, and, I think maybe partly due to resistance of the caster or trailing geometry. I wonder if resistance due to trailing geometry also increases with speed.

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Another thing worth thinking about is when you flick the bike back up, say a set of esses or what you call the knee to knee drill!

e.g. if you flick the bike from left to right to 45 degrees does it require more effort in the upward motion (against gravity) than moving in the downward motion (with gravity)? Does the bike go downwards faster than upwards,

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Another thing worth thinking about is when you flick the bike back up, say a set of esses or what you call the knee to knee drill!

e.g. if you flick the bike from left to right to 45 degrees does it require more effort in the upward motion (against gravity) than moving in the downward motion (with gravity)? Does the bike go downwards faster than upwards,

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I have to disagree with you on the "because of gravity" there is friction point. The friction that we need in any land based vehicle is rolling friction and is an OPPOSING FORCE. It is this opposing force that gives us traction.

Um... okay. What do you think causes friction at the contact patch of a motorcycle driving in a straight line, Jay?

I understand your analogy regarding moment and center of gravity and I think you're onto something with explaining one of the forces involved in countersteering initiating the lean angle.

Cool. You are the first person to say you understood my analogy. Thanks.

So, what other force(s) do you think are involved?

Let us keep in mind that gravity is not a force that necessarily is downward.

Erm... really? In what other direction does gravity act here on planet Earth?

Once lean has been established it is gravity that keeps us from falling over by application of throttle and is also why the suspension compresses and causes the bike to loose further ground clearance.

With all due respect, Jay, I think you might be mixing gravity up with some other force(s). Here is a link to an excellent online website for Physics and Kinematics (presented in plain English) that I found very helpful.

Gravity strictly by definition is the attractive force between two bodies, which is why I said it's not necessarily "down". We are attracted to the center of that mass, the Earth. But as we know from Newton's first law, there is an opposite force in the opposing direction. That point is not really relevant to this conversation, but I just hope to clear up the muddiness of my other comment. The fact is that gravity's vector can change based on other influences. And since we love specifics, up and down are relative terms because the Earth is the sphere that we ride on.

There is a constant F of G in the vertical, but as you get on the gas, the only Force we're concerned about is the one created by the change of direction in the horizontal, thereby giving us traction to execute the turn (and the road/tire forcing against each other) keeping us from falling onto the ground.

I hope that I only cleared up my earlier comments. I do not want to throw my hat into the ring on the discussion of gyroscopic effect, as I have nothing of worth to contribute to that discussion.

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QUOTE

I am entering a discussion, not an arguement!

If it takes 1 tenth of a secnd for an object to fall 1 metre, if gravity pulls the bike down, wouldn't it be possible to steer your bike to the desired lean angle in less than 0.1 of a second, can anyone steer this fast? Say from upright to 45 degrees probably a distance of less than half a metre. Take a sportsbike, at 20 mph it is easy to steer to 45 degrees but what about when you go faster say 60 mph, does it require more effort to turn? what kind of effort does it need? is it push the bars harder? or push the bars faster? or both?

You know, I think you might really be onto something here, Bobby. Not only about the time it takes to lean the bike, but, also the difference at different road speeds. This is what I was thinking about today while communing with a 600RR and meditating on Will's leverage angles. The amount of force and leverage it takes to turn the front wheel increases greatly with speed. Partly due to the increase in resistance of gyroscopic forces, and, I think maybe partly due to resistance of the caster or trailing geometry. I wonder if resistance due to trailing geometry also increases with speed.

--------------------

There is no spoon!

I try to use my riding as an example but on my best day I can turn a bike about as fast as anyone, that would be 1 to 2 tenths from vertical to full lean. I didn't know the exact number for gravity but it seems to be very close to my experience.

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Another thing worth thinking about is when you flick the bike back up, say a set of esses or what you call the knee to knee drill!

e.g. if you flick the bike from left to right to 45 degrees does it require more effort in the upward motion (against gravity) than moving in the downward motion (with gravity)? Does the bike go downwards faster than upwards,

I don't know which way is faster but I can say I have turned bikes from knee to knee fast enough that the wheels leave the ground. Driving the front wheel under the bike fast enough to bottom the forks and compress the rear, with both rebounding and the increase in radius from the side of the tire to the center effectively jumping the bike right off the ground. I don't think you can turn it from straight up and down to lean faster than gravity will pull it down, but clearly gravity can defeated coming from leaned to straight up.

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I don't know which way is faster but I can say I have turned bikes from knee to knee fast enough that the wheels leave the ground. Driving the front wheel under the bike fast enough to bottom the forks and compress the rear, with both rebounding and the increase in radius from the side of the tire to the center effectively jumping the bike right off the ground. I don't think you can turn it from straight up and down to lean faster than gravity will pull it down, but clearly gravity can defeated coming from leaned to straight up.

Where in the world can this be done? is it a CSS drill? Sounds like fun.

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I don't know which way is faster but I can say I have turned bikes from knee to knee fast enough that the wheels leave the ground. Driving the front wheel under the bike fast enough to bottom the forks and compress the rear, with both rebounding and the increase in radius from the side of the tire to the center effectively jumping the bike right off the ground. I don't think you can turn it from straight up and down to lean faster than gravity will pull it down, but clearly gravity can defeated coming from leaned to straight up.

Where in the world can this be done? is it a CSS drill? Sounds like fun.

[/quote

Will's pretty amazing at turning a bike, has been as long as I've known him. That's a skill that can take a bit of work. There should be some good footage of this when Keith gets done with the Twist 2 DVD, which he is working on now, big time.

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Okay, I had imagined just going knee to knee in a straight line or something (silly me). I suppose this can be done in any good set of esses? Yes?

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Okay, I had imagined just going knee to knee in a straight line or something (silly me). I suppose this can be done in any good set of esses? Yes?

I believe it can be practiced anywhere there is enough space, like in a paddock at a race track or a car park! dont know what sort of speed you should aim to do it at though!

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Okay, I had imagined just going knee to knee in a straight line or something (silly me). I suppose this can be done in any good set of esses? Yes?

I believe it can be practiced anywhere there is enough space, like in a paddock at a race track or a car park! dont know what sort of speed you should aim to do it at though!

Warms the tires on both sides

C

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Okay, I had imagined just going knee to knee in a straight line or something (silly me). I suppose this can be done in any good set of esses? Yes?

I believe it can be practiced anywhere there is enough space, like in a paddock at a race track or a car park! dont know what sort of speed you should aim to do it at though!

Warms the tires on both sides

C

What's the smilie for a bad joke :-)

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Okay, I had imagined just going knee to knee in a straight line or something (silly me). I suppose this can be done in any good set of esses? Yes?

I believe it can be practiced anywhere there is enough space, like in a paddock at a race track or a car park! dont know what sort of speed you should aim to do it at though!

Warms the tires on both sides

C

What's the smilie for a bad joke :-)

It's just been that we've had guys (even coaches) on cooler days, forget that tires have to be warmed on both sides. If you are going to go from one knee to the other, want to make sure the tires are going to stick!

C

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Didn't we have the discussion elsewhere about the proper way to warm tires??? I think it's also discussed in the current issue of Sport Rider.

Or did I forget to take my dyslexia medication again?

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Didn't we have the discussion elsewhere about the proper way to warm tires??? I think it's also discussed in the current issue of Sport Rider.

Or did I forget to take my dyslexia medication again?

I don't recall if we did, but it has come up so much at the schools, guys not really knowing how to do it, I've been making more of a point of going over it. Haven't see the SR issue yet, I'll have a look.

C

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At the risk of exposing my inner self (SQUID) the first time I found out about this was when lane splitting and changing from splitting the one two lane to the two three lane, warm tires, sunlight, ect.

I don't recommend going out and "trying" to do this. I snuck up on it with my Daytona special RD400 some months before it departed this place in a big ball, a wheelie gone very wrong.

at this point I have figured out how to keep the tires on the ground, if I do it now it is for demonstration or a mistake in turning too fast for the bike I am on.

Will

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At the risk of exposing my inner self (SQUID) the first time I found out about this was when lane splitting and changing from splitting the one two lane to the two three lane, warm tires, sunlight, ect.

I don't recommend going out and "trying" to do this. I snuck up on it with my Daytona special RD400 some months before it departed this place in a big ball, a wheelie gone very wrong.

at this point I have figured out how to keep the tires on the ground, if I do it now it is for demonstration or a mistake in turning too fast for the bike I am on.

Will

This is very interesting, I work alot on my quick turns and sometimes wonder what would be too fast, I think its probably best to keep your tyres on the ground but knowing you have the abbility to make the bike jump must give you the confidence that you know the limits of that particular area of riding, these are the limits that I would like to acheave! I am looking forward to getting on the lean bike as I feel that this will be a big step towards reaching the limits!

I have a question though, in a chicane type corner, what would be the correct method of turning say you are all the way over to the left and want to flick right, should you stay on the gas left to right, back it of a little or close completely and crack open and roll on again when you have turned right?

Thanks

B

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... it seems to me what you are saying is it's not gravity but what it creates that is responsible for the bike leaning?

Thank you for asking that question, Will.

I said that gravity and what it creates (friction) is responsible for the tire sticking to the pavement.

And I said I think that momentum is the source of potential energy tapped by the geometry of the "twist induced into the steering head" (as you said) for horizontal (wrt the bike) force to induce roll and a quick turn/flick rather than merely a fall due to gravity.

I also said that gravity adds a vertical component of force to the leaning, but, that, by definition, it doesn't account for much motion above 45 degrees of lean.

In any case, I think Bobby pretty much closed the issue of gravity vs momentum by pointing to the ability to flick the bike back up.

I don't think I will have time to continue my simple, plain English treatment of the physics where I left off with the narrow "single track" and the different types of momentum until late Wednesday at the earliest.

Have a great weekend! Go Steelers!

BH

PS - The title under your photo at left still says "Riding Coach". Are you going to change it to "Mechanic"?

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PS - The title under your photo at left still says "Riding Coach". Are you going to change it to "Mechanic"?

The webmaster thinks it funny to change my stuff?

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[quote name='acebobby' date='Oct 4 2008, 11:10 PM' post='7353'

I have a question though, in a chicane type corner, what would be the correct method of turning say you are all the way over to the left and want to flick right, should you stay on the gas left to right, back it of a little or close completely and crack open and roll on again when you have turned right?

Thanks

B

quote]

That is an open ended question with sooooooo many answers. Take Barber for example, the back straight chicane. It is about a 100 mph left to right flick. I will dip the gas to turn the left and get right back in it and for the left to right I will dip to about half throttle.

Streets of willow turn 11 to 12 (skid pad) I will come into it with the rear at the limit ( 3/4 throttle) and just before the right to left flick goose it to break the rear loose and as I drop the throttle use the front brake a tiny amount to get the bike to counter steer itself as the rear hooks up and tries to high side the bike. I would call this passive steering, I don't have to "steer the bike with the bars until it is almost upright.

That looks a lot scarier in writing!

Just two examples, the ends of the spectrum in answers to your question.

Will

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Streets of willow turn 11 to 12 (skid pad) I will come into it with the rear at the limit ( 3/4 throttle) and just before the right to left flick goose it to break the rear loose and as I drop the throttle use the front brake a tiny amount to get the bike to counter steer itself as the rear hooks up and tries to high side the bike. I would call this passive steering, I don't have to "steer the bike with the bars until it is almost upright.

That looks a lot scarier in writing!

You can say that again

That looks a lot scarier in writing!

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