Counter Rotating Brakes Vid

[PSk]

Originally Posted by Dezmo

OK, I have put some thought into this, and theres one major flaw with thinking the bike 'falls' into the corner without the influence of gyros, and its the one force that cannot be cancelled out while on earth.....gravity.

Watch a GP or Superbike race sometime, and pay close attention to a particulary tight corner.....see how fast those guys slam the bikes over? Gravity alone cannot do this....if you need proof go hold your bike upright, then tip it just off center and let go....it will fall but it takes a second or so for any speed to build up. (You dont really have to do this, just using an example). If gravity isnt moving the bike over that fast, what is?

When a bike corners the tyres grip the road, thus the bike is trying to push the road away. But the road cannot be pushed away and the earth has too larger mass for this bike cornering process to make it move ... thus where has all this force gone?

Obviously if the rider has not leaned the bike over enough this cornering force will make the bike stand up and he/she will crash.

If the rider leans over correctly to balance the force then that force has been BALANCED and all the cornering G's are going directly down through the CoG of the bike and rider combination. Thus if the rider wants to change the cornering direction/line of the bike he just needs to alter the bike and rider combination's CoG again. As the bikes is perfectly force balanced this takes no more effort than if the bike was vertical EXCEPT he/she now has the cornering G force to counter. This unfortunately makes it harder for the rider to move because they will be Gcornering * their mass heavier.

Counteracting their request for the bike to alter direction will be the gyroscopic force of any rotating object on the bike, definitely not aiding their request for the bike to lean.
Pete

[Dezmo]

Originally Posted by PSk

When a bike corners the tyres grip the road, thus the bike is trying to push the road away. But the road cannot be pushed away and the earth has too larger mass for this bike cornering process to make it move ... thus where has all this force gone?

Obviously if the rider has not leaned the bike over enough this cornering force will make the bike stand up and he/she will crash.

If the rider leans over correctly to balance the force then that force has been BALANCED and all the cornering G's are going directly down through the CoG of the bike and rider combination. Thus if the rider wants to change the cornering direction/line of the bike he just needs to alter the bike and rider combination's CoG again. As the bikes is perfectly force balanced this takes no more effort than if the bike was vertical EXCEPT he/she now has the cornering G force to counter. This unfortunately makes it harder for the rider to move because they will be Gcornering * their mass heavier.

Counteracting their request for the bike to alter direction will be the gyroscopic force of any rotating object on the bike, definitely not aiding their request for the bike to lean.
Pete

All 100% correct, except you forgot one small detail.
there is one gyro that can be moved in relation to the rest of the bike/rider (or in other words, have force applied to it.)....the front wheel....precession does the rest.

[PSk]

Oh dear!

Originally Posted by Dezmo

completely false....do you even understand what gyroscopic procession is? Simply put, any force applied to a spinning gyro will affect it 90 degrees in the direction of rotation....like when you try to turn the wheel sideways, but the bike leans over? make more sense now?

Der, this is exactly what centrifugal force is. This a wheel spins around an axis and the force is 90 degrees to that axis ... not inwards or outwards but perpendicular to that axis.

Its well doccumented that a bike rotates around its center of gravity when it leans into a turn, not around the contact patches. The bike leans right, the tire contact patch moves left. Nothing magical going on here, as the wheel is rolling as its path deviates and no loss of grip is needed.

The tyre patch cannot move it is connected via grip to the road. The tyre does not move left the bike just leans right. Remember the CoG of the bike and rider combination have moved right also thanks to the lean.

As to weight overcoming the gyro force....as I stated earlier, gravity doesnt overcome it, it works with it.

I think you need to go and get a childs bicycle wheel and hold it by it's axle. Get somebody to spin it and try and see if this spinning of the wheel wants to make your hands move (thus simulate a bike wanting to lean) OR wants to make your hands move so the axle is horizontal.

It will make your hand move so the axle is horizontal and thus resist you wanting to move the axle or wheels axis around. Correction: This is incorrect, please see next post of mine

Please note it is possible that we are trying to say similar things but thanks to terms and the written word we are miss-communicating ... it happens
Pete

[PSk]

Dezmo,

You are correct regarding gyroscopic precession. I did some research and I am wrong. If you take that child's bicycle wheel and hold it's axle apparently the second you move it out of vertical it will want to move so that the axle is vertical.

Originally Posted by http://www.boomerangs.com/gyroscope.html

Gyroscopic precession is the tendency of the spin axis of a rotating object to twist at right angles. This effects all spinning bodies including the planet Earth, which wobbles on its axis like a top (commonly called precession of the equinoxes). You can test this force by gripping the axel of a spinning wheel and trying to tilt it. The twisting motion that results is due to gyroscopic precession. It is the effect of gyroscopic precession that makes a moving two wheelled bike turn in the direction that the rider leans.

Pete

[Dezmo]

Originally Posted by PSk

This a wheel spins around an axis and the force is 90 degrees to that axis ... not inwards or outwards but perpendicular to that axis.

EXACTLY! and what happens when we apply some force to the horizontal axis of a spinning wheel....it tries to LEAN OVER. However, in the case of the spinning top, centrifugal force simply pushes in all directions equally, so it has essentially 0 effect on the top's lean. The top is actually constantly trying to fall over, but precession moves the force 90 degrees before it can, and it stays upright, always 'falling' 90 degrees behind the force.

Originally Posted by PSk

The tyre patch cannot move it is connected via grip to the road.

but this is a rolling patch, not constant....if you couldnt change a contact patch's path, no vehicle would turn

Originally Posted by PSk

I think you need to go and get a childs bicycle wheel and hold it by it's axle. Get somebody to spin it and try and see if this spinning of the wheel wants to make your hands move (thus simulate a bike wanting to lean) OR wants to make your hands move so the axle is horizontal.

It will make your hand move so the axle is horizontal and thus resist you wanting to move the axle or wheels axis around.

Been there done that, back in middle school science class.....see above for how it applies to front wheels

Originally Posted by PSk

Please note it is possible that we are trying to say similar things but thanks to terms and the written word we are miss-communicating ... it happens
Pete

I think we are in agreement on several factors here actually...I just dont think you give the gyroscopic forces enough credit

[PSk]

Originally Posted by Dezmo

but this is a rolling patch, not constant....if you couldnt change a contact patch's path, no vehicle would turn

True but my front wheel does not go move left of the bikes CoG when I turn right. Instead the bikes CoG goes to the right. Same thing from different view points. You are viewing the bike as the stationary object ... it is not in the real world.

I think we are in agreement on several factors here actually...I just dont think you give the gyroscopic forces enough credit

Quite possible.

Another interesting site: http://www.gyroscopes.org/behaviour.asp

The thing is that if you made the worlds lightest possible wheels and thus the minimal gyroscopic affect you would still be able to turn a bicycle or m/c. Thus I have to believe they affect how a bike turns, but do not initiate the turn, that is definitely done by altering the CoG of the bike and rider combination, causing the lean.

Pete

[Dezmo]

Originally Posted by PSk

The thing is that if you made the worlds lightest possible wheels and thus the minimal gyroscopic affect you would still be able to turn a bicycle or m/c. Thus I have to believe they affect how a bike turns, but do not initiate the turn, that is definitely done by altering the CoG of the bike and rider combination, causing the lean.

Pete

you need to ride keith code's "no BS" bike....I myself have not, but it would show you just how little effect shifting weight has on a bike's turning ability.

[PSk]

Originally Posted by Dezmo

you need to ride keith code's "no BS" bike....I myself have not, but it would show you just how little effect shifting weight has on a bike's turning ability.

Hmmm ... then I'm starting to believe Banda then, it is the shape of the tyre and the lean that initiates the turn.

EDIT: Thinking about it sorry, I cannot agree that shifting weight does not have much do with turning ability. We all understand that a bike will turn if it is leant one way of the other. Thus if you do not keep the CoG of the bike and rider combination in the centre the bike has to lean ... and thus turn. Yeah I can ride straight and be hanging off one side ... but I will be countering that with angling the bike the other way to restore the CoG to central (for the bike and rider combination). This statement contradicts Banda's theory on type shape relating to initiating the turn BTW, cause now we would be running on the tyre sides and NOT turning.

Gyroscopic presession may then help the turn ... but they cannot initiate it as the wheels axle must be moved first!
Pete

[Dezmo]

Originally Posted by PSk

Hmmm ... then I'm starting to believe Banda then, it is the shape of the tyre and the lean that initiates the turn.

Gyroscopic presession may then help the turn ... but they cannot initiate it as the wheels axle must be moved first!
Pete

Banda is absolutely correct about the bike changing direction because of the tire's shapes...this is why wider tires make steering heavier. But precession (with a lil help from gravity) is what leans it over.

and the wheel's axle CAN BE MOVED...just turn the handlebars

but in reality, when countersteering we arent really moving the bars much, if at all, but putting force thru them, which is the force that becomes the lean once precession is done with it.

[AZ Scott]

Oh. My. God.

I'm glad middle-school science teachers aren't building motorcycles, or we'd all be doomed to die a horrible death!

A few points you guys need to get your head around:

- The lighter you make the wheels (i.e. LESS gyroscopic force) the BETTER and FASTER it will turn. There is no limit! There is no magical number at which the motorcycle will no longer turn. Gyroscopic forces only HINDER steering, they do not help it in any way.

- When a motorcycle is leaned into a corner, the center of gravity does NOT move in relation to the motorcycle's original path. If you make the bike lean into a RIGHT turn, you DO, in fact, move the tires' contact patches to the LEFT.

- This does not happen because of gyroscopic force. It happens because you STEERED the tires to the left! (Actually, you steered the FRONT tire to the left - the rear tire will always follow the front because they are connected by a motorcycle).

- Once you steer the front tire to the left, the motorcycle will immediately fall to the right - GRAVITY - until you tell it to stop falling by steering the front tire back to the right until you find the balance point of the lean angle you want.

- Give us a break with the damn bicycle-wheel-sitting-on-a-stool-and-turning-it science experiment. It has nothing to do with this!

- I'll repeat that: IT HAS NOTHING TO DO WITH THIS!

- When you turn into a corner, you don't turn the bars NINETY FRIKKIN' DEGREES to either side. You turn it a few degrees at most. The faster the turn, the less you move the bars. As in, less than 5 degrees.

- The gyroscopic forces caused by the crankshaft and other engine parts also do not help steering. A motorcycle is perfectly capable of being ridden - and turned - with the engine not even running.

**************************************

You guys all correct about some of these things, and completely off-base about some other things. But this myth about motorcycles turning BECAUSE of gyroscopic precession is the biggest fallacy in the world of motorcycles.

I'm still waiting for someone to show me that Kevin Cameron is actually helping to propagate this story...

[Dezmo]

Scott, you need to take a valium and do some reading
you are correct about some things, but most of the stuff you are way off-base on. I wont get into details cause youd just nitpick them to death, but seriously, do some studying before shooting your mouth off

[AZ Scott]

I guess we'll just have to agree to disagree, Dezmo.

Because no amount of reading will convince me that you're not full of shit.

[Dezmo]

ahh, screw it, I will get into it

Originally Posted by AZ Scott

Oh. My. God.

he's not yours, he's everybody's

Originally Posted by AZ Scott

A few points you guys need to get your head around:

- The lighter you make the wheels (i.e. LESS gyroscopic force) the BETTER and FASTER it will turn. There is no limit! There is no magical number at which the motorcycle will no longer turn. Gyroscopic forces only HINDER steering, they do not help it in any way.

yes and no....lighter wheels help because they take less force to change direction (to induce precession) but the important point is, they still create gyro forces....for this reason there is a lower limit on how light a wheel can be.

Originally Posted by AZ Scott

- When a motorcycle is leaned into a corner, the center of gravity does NOT move in relation to the motorcycle's original path. If you make the bike lean into a RIGHT turn, you DO, in fact, move the tires' contact patches to the LEFT.

I agree 100%

Originally Posted by AZ Scott

- This does not happen because of gyroscopic force. It happens because you STEERED the tires to the left! (Actually, you steered the FRONT tire to the left - the rear tire will always follow the front because they are connected by a motorcycle).

See my previous post about not actually moving the wheel, but putting force thru it.

Originally Posted by AZ Scott

- Once you steer the front tire to the left, the motorcycle will immediately fall to the right - GRAVITY - until you tell it to stop falling by steering the front tire back to the right until you find the balance point of the lean angle you want.

so tell me, if it JUST gravity, how do you hold a lean angle or correct it? by making the bike lean the other way? your tire is waaay over there now, you cant get weight onto the other side of it....precession is the ONLY way you can do this.

Originally Posted by AZ Scott

- Give us a break with the damn bicycle-wheel-sitting-on-a-stool-and-turning-it science experiment. It has nothing to do with this!

- I'll repeat that: IT HAS NOTHING TO DO WITH THIS!

no matter how loud you yell, it has everything to do with this.

Originally Posted by AZ Scott

- When you turn into a corner, you don't turn the bars NINETY FRIKKIN' DEGREES to either side. You turn it a few degrees at most. The faster the turn, the less you move the bars. As in, less than 5 degrees.

you dont need to turn the bars 90 degrees, just put force thru them....again, read what I have already said about lack of actual bar movement.

Originally Posted by AZ Scott

- The gyroscopic forces caused by the crankshaft and other engine parts also do not help steering. A motorcycle is perfectly capable of being ridden - and turned - with the engine not even running.

who said the other gyros on the bike help turning? they are what is keeping the bike upright in the 1st place. If anything, they resist the change of direction.

Originally Posted by AZ Scott

You guys all correct about some of these things, and completely off-base about some other things. But this myth about motorcycles turning BECAUSE of gyroscopic precession is the biggest fallacy in the world of motorcycles.

Gee, I thought that it was "harley davidsons are the best motorcycles in the world"

[AZ Scott]

Okay, my turn to nit pick...

Originally Posted by Dezmo

yes and no....lighter wheels help because they take less force to change direction (to induce precession) but the important point is, they still create gyro forces....for this reason there is a lower limit on how light a wheel can be.

So what is that limit? Do you really think that a wheel/tire/brake combo that weighed, say, 2 lbs. would make it so you couldn't turn the bike? How about 1 lb.? 3 ounces?

I agree 100% (re: CoG)

Yeah, that was for PSK. He got everything right except that...

See my previous post about not actually moving the wheel, but putting force thru it.

Okay, how much force are you talking about? Personally, I can get a motorcycle to flick over to full lean at 50mph by barely pushing on the inside bar. So how much "gyroscopic" force could I possibly be introducing into the system?

so tell me, if it JUST gravity, how do you hold a lean angle or correct it? by making the bike lean the other way? your tire is waaay over there now, you cant get weight onto the other side of it....precession is the ONLY way you can do this.

You hold your lean angle by keeping the tire contact patches at the correct point in relation to the CoG. If you want a little more lean, you steer the front tire a little further away from the corner. If you want to stand it up a little, you steer the front tire toward the inside of the corner.

If you want to flick it from full right lean to full left lean quickly, you give it a nice firm push on the left handlebar. That causes the contact patch to move from the left side of the bike to the right side, and the rear tire contact patch naturally follows.

The center of gravity of the bike simply moves straight upward, and then back down as the bike changes direction.

This is why I used my downhill skier as an example earlier. To you, it's apples and oranges, but it's the same principle at work. Both things - a skier and a motorcycle - need to lean to turn. With both, the idea is to get the part that's connected to the ground to be on the outside of the turn. The skier moves his skis underneath him, and the motorcycle rider moves his tires underneath him. SAME THING.

who said the other gyros on the bike help turning? they are what is keeping the bike upright in the 1st place. If anything, they resist the change of direction.

I dunno, somebody up there said something about engine internals having more of a gyroscopic effect on things than the wheels. I just wanted to get that aspect out of the way, because it's a moot point.

Gee, I thought that it was "harley davidsons are the best motorcycles in the world"

Okay, 2nd biggest fallacy...

[Dezmo]

Originally Posted by AZ Scott

So what is that limit? Do you really think that a wheel/tire/brake combo that weighed, say, 2 lbs. would make it so you couldn't turn the bike? How about 1 lb.? 3 ounces?

there is no actual number that you cannot go below, its a percentage of the bike's mass.

Originally Posted by AZ Scott

Okay, how much force are you talking about? Personally, I can get a motorcycle to flick over to full lean at 50mph by barely pushing on the inside bar. So how much "gyroscopic" force could I possibly be introducing into the system?

again, I never said gravity did nothing, but precession is what makes the reaction that quick.

Originally Posted by AZ Scott

You hold your lean angle by keeping the tire contact patches at the correct point in relation to the CoG. If you want a little more lean, you steer the front tire a little further away from the corner. If you want to stand it up a little, you steer the front tire toward the inside of the corner.

If you want to flick it from full right lean to full left lean quickly, you give it a nice firm push on the left handlebar. That causes the contact patch to move from the left side of the bike to the right side, and the rear tire contact patch naturally follows.

The center of gravity of the bike simply moves straight upward, and then back down as the bike changes direction.

This is why I used my downhill skier as an example earlier. To you, it's apples and oranges, but it's the same principle at work. Both things - a skier and a motorcycle - need to lean to turn. With both, the idea is to get the part that's connected to the ground to be on the outside of the turn. The skier moves his skis underneath him, and the motorcycle rider moves his tires underneath him. SAME THING.

Skiers fit perfectly into this explanation, but motorcycles are a bit more complex. You are correct about the movement of the CG, but if it was just you turning the wheel that made the bike lean/stand up, youd wear out fronts far faster than rear tires...not to mention youd need arms like a gorilla to steer a tire into the ground (if like you said, steering forces are what changes the lean)

[PSk]

Originally Posted by AZ Scott

Yeah, that was for PSK. He got everything right except that...

I try but I am not perfect , actually this comment helped me understand what you guys mean:

Originally Posted by AZ Scott

You hold your lean angle by keeping the tire contact patches at the correct point in relation to the CoG. If you want a little more lean, you steer the front tire a little further away from the corner. If you want to stand it up a little, you steer the front tire toward the inside of the corner.

Now I think I get this part.

Originally Posted by Dezmo

so tell me, if it JUST gravity, how do you hold a lean angle or correct it? by making the bike lean the other way? your tire is waaay over there now, you cant get weight onto the other side of it....precession is the ONLY way you can do this.

You are forgetting about cornering G forces ... I have already stated that to alter the bike lean angle you need to alter your bike and rider combination CoG related to the G force direction ... not just gravity (as in straight down to earth). This is exactly the same as for riding in a straight line and wanting the bike to lean one way or another EXCEPT that you now have cornering G's involved.

Pete

[PSk]