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Balance Beads, ever use them?

To see what is meant by 'free to move' rather than 'fixed' as on a dynamic balancer, watch the video by Centramatic in post #43.
45 seconds in, you will see the axle wobbling; a dynamic balancer shaft doesn't allow that to happen.
 
MotorradMike said:
To see what is meant by 'free to move' rather than 'fixed' as on a dynamic balancer, watch the video by Centramatic in post #43.
45 seconds in, you will see the axle wobbling; a dynamic balancer shaft doesn't allow that to happen.
Click to expand...

Yes, the rear axle on Voni's F800S wobbled just like that when the axle tube and bearings shot craps. I've seen a couple of GSs with wobble like that, too, when their final drives failed.
 
Beads vs Balancer

Next time you are at a road race (with a pit pass), look to see what the racers use on their tires. Hint: It's not beads. There is usually a static balancer and weights--and these guys depend on the tires outlasting the competitors.
I have changed my own tires for quite a few years now, and always balance check the bare rim and mark the heavy spot. It's not necessarily the fill valve--depends on how the rim was put together.
Some tire manufactures have dispensed with marking the "light spot" like they all used to--so then its just a crapshoot on where to seat the tire on the rim without checking and rotating. PITA. My last Michelins came with no mark, Shinkos have a mark, but are inconsistent. Metzlers, even though some are made in China, have the light spot marked.
One of the easiest ways to balance a "no mark" tire is to only seat one bead, masking tape the tire to the rim, then check it on your static balancer to see how much weight it will require--then you can rotate it 90 degrees and check again without too much difficulty. Hope this helps! :brow
 
Arkyride said:
Next time you are at a road race (with a pit pass), look to see what the racers use on their tires. Hint: It's not beads. There is usually a static balancer and weights--and these guys depend on the tires outlasting the competitors.
Click to expand...

Yes, don't put them in your race bike. See post #12.
 
How do they work?
The basic principle behind how Dyna beads work is based on Isaac Newton's First Law of Physics - The law of Inertia. It states that a body at rest will tend to stay at rest. When there is a heavy spot on a wheel/tire, it tends to make that spot move away from the center when the wheel spins.

As I understand this statement, the heavy spot stretches the spinning tire so the radius might be slightly greater at that point. But then I imagine myself in a tiny hamster ball rolling inside the tire, and that greater radius looks like a dip in the road, a perfect spot to settle. The light spot, closer to the axle, is more of a hilltop, and not a very stable point to take a rest.

This is the exact opposite of the desired result.

Pending a more rational explanation, I think I'll stick to my Parnes balancer and some weights.
 
Today I stopped by the local Les Schwab tire store and asked the pros what they thought about balance beads. They told me that they have the beads in stock but only use them if a customer requests it rather than spin balance. they also said that they don't use the beads for passenger cars or light trucks only heavy trucks and motor homes. Les Schwab is a tire store chain found mostly throughout the Pacific Northwest including Montana and N. California and they are probably the most used tire store with a sterling reputation. They also said that they have seen the beads cause flat tires all to often because the beads tend to powder inside the tire and get caught in the valve core so that when you top off the tire the slight puff of air that occurs when the air filler is removed results in this powder getting stuck in the valve stem creating a slow leak.

It would be great if the beads really worked as well as spin balancing but.........
 
At the risk of upsetting someone...there is a reason why we have used weights forever - they work.
The concept of beads is nothing new and if really effective would have replaced weights long ago.
YRMV.
 
physics schmysics

I think the dynabeads explanation is pretty bad. I'll try to give a better one.

Instead of a wheel on an axle, imagine throwing a spinning object. Its motion can be broken down into two components: the center of gravity of the object will follow a smooth ballistic curve (until it hits the ground), and the object will rotate around its center of gravity. If the object is a stick with a heavy and a light end, the center of gravity will be closer to the heavy end, and the heavy end will describe small circles around the center of gravity, while the light end will follow larger circles. The only point on (or in) the stick that follows a smooth path without any oscillation around it is the center of gravity. (You could say that this is the definition of the center of gravity. The earth's force on the object can be imagined to only influence the path of the center of gravity, and the rest of the object spins freely around it, just like it would in outer space.)

Now imagine the freely spinning object is your out-of-balance wheel. Since nothing is holding the axle, the wheel will not spin around its geometric center (like it would do if it were on a balancer or a bike without suspension), but, just like the stick before, the wheel will spin around its center of gravity, which will be offset from its geometric center (the axle hole) towards the heavy spot on the wheel. The heavy spot will make a smaller circle around the center of gravity, and the light side will follow a slightly larger path. The wheel will wobble through space, until it hits the ground.

Now imagine putting some light moveable objects (balls) inside the tire. Since they are free to move around, they will 'fall' along the circumference of the tire to the point farthest away from the center of gravity. With a bit of friction they will eventually come to rest there. Each ball you add will reduce the imbalance of the wheel a bit, until it is balanced and its center of gravity coincides with its geometric center. Any balls you add after that point will no longer see a 'far' or 'low' point to fall to, and are free to distribute themselves evenly around the wheel. Any momentary imbalance will immediately lead to an offset between center of gravity and geometric center, there will be a side of the wheel further away from the center of rotation, and some balls will travel there until the wheel is balanced again. So you could add too few balls, but you can't add too many. As long as there is an imbalance, and the wheel wobbles a bit, with the light spot describing a larger circle, the moveable weights will travel to that spot making the large circle, and balance the wheel in the process.

Putting the wheel on your motorbike, and rolling along, it becomes clear that the balancing action only can take place if the wheel is allowed to bounce around a bit by the suspension. If there is no bounce, the wheel will always be forced to rotate around the axle. But if the axle is mounted with enough 'give' the center of gravity will try to follow a smooth path, making the light side of the wheel describe slightly larger circles and the heavy side smaller ones. Objects inside the tire will 'fall' or travel towards the spot making the largest circle, and in doing so reduce the imbalance.

So far it didn't matter whether you imagined a flat 2 dimensional object or a real 3D one, with some width. But now imagine that the heavy spot on your wheel is off to one side of the rim. That spot will try to follow the smallest circle, and the point diametrically opposite, half way around the wheel and on the other side, will try to follow the larger circle. (The wheel, like any body, wants to rotate around the axis with the largest moment of inertia, which in this case is not parallel to the axle.) But a normal motorbike suspension will not let it do that. It will keep the axle parallel to the ground, and not allow the wheel to rotate the way it 'wants to'. That's why the objects inside the tire cannot balance a wide wheel that might require different weights placed on the left and right side (or inside and outside, on a car) of the rim.

I hope this helps. If you have difficulty visualizing the out of balance wheel freely spinning around its center of gravity, start with an odd shaped asteroid in outer space, or a stick with a rock tied to one end.
 
Hi Gruesome, I get your point and I think you are saying that beads may be better suited to wheel/tire balancing on a motorcycle than on an automobile because of tire dimensions specifically width. On occasion I have had slightly better success with my static balancer by placing the weights on opposite sides of the rim, rare to find a motorcycle tire that requires this however.

I'll still go with weights and a static balancer especially after today's discussion with the tire guys.
 
Point missed.

happy wanderer said:
So far we have "Did you catch the before and after?", they were no good on truck tires which is what I have to guess you are referring to along with a sort of "what's wrong with the spinning bottle video" challenge.

Wouldn't it be easier (and more helpful) to just enlighten us as to what you think is wrong with the video?
Click to expand...

This thread can go forever, as it has in the past. Whatever works for you, works for you. I don't like some engine oils but I have different concerns than my neighbour. No big deal. His beads, my weights. Sit and drink a few wobbly pops and chat about the differences? Disagree? Sure! Is he wrong? Am I so smart as to tell him he is wrong?

Beads, sold them, didn't work for my customers. 'Nuff said there. Will they work for you? If you are happy and they do what you want, who is to say you are wrong?

If they don't work, bust the bead, scoop out the crap, start over. Dynamic or Static balancing doesn't work, I got hundreds of pounds of beads over ten years old I can sell you, cheap.

If some of us remember that torque wrench on a bearing test at midnight on TV, Slick 50, I think, and the squeal before and after, watch the commercial again and pay attention to the before force use and pay attention to the force used for Slick 50. That commercial was less obvious than the "Bead Video" where he varied the speed of the drill on a radius smaller than the length of the axis.

A hockey puck is out of balance until it gets some momentum.
 
Gruesome said:
I think the dynabeads explanation is pretty bad. I'll try to give a better one.

Instead of a wheel on an axle, imagine throwing a spinning object. Its motion can be broken down into two components: the center of gravity of the object will follow a smooth ballistic curve (until it hits the ground), and the object will rotate around its center of gravity. If the object is a stick with a heavy and a light end, the center of gravity will be closer to the heavy end, and the heavy end will describe small circles around the center of gravity, while the light end will follow larger circles. The only point on (or in) the stick that follows a smooth path without any oscillation around it is the center of gravity. (You could say that this is the definition of the center of gravity. The earth's force on the object can be imagined to only influence the path of the center of gravity, and the rest of the object spins freely around it, just like it would in outer space.)

Now imagine the freely spinning object is your out-of-balance wheel. Since nothing is holding the axle, the wheel will not spin around its geometric center (like it would do if it were on a balancer or a bike without suspension), but, just like the stick before, the wheel will spin around its center of gravity, which will be offset from its geometric center (the axle hole) towards the heavy spot on the wheel. The heavy spot will make a smaller circle around the center of gravity, and the light side will follow a slightly larger path. The wheel will wobble through space, until it hits the ground.

Now imagine putting some light moveable objects (balls) inside the tire. Since they are free to move around, they will 'fall' along the circumference of the tire to the point farthest away from the center of gravity. With a bit of friction they will eventually come to rest there. Each ball you add will reduce the imbalance of the wheel a bit, until it is balanced and its center of gravity coincides with its geometric center. Any balls you add after that point will no longer see a 'far' or 'low' point to fall to, and are free to distribute themselves evenly around the wheel. Any momentary imbalance will immediately lead to an offset between center of gravity and geometric center, there will be a side of the wheel further away from the center of rotation, and some balls will travel there until the wheel is balanced again. So you could add too few balls, but you can't add too many. As long as there is an imbalance, and the wheel wobbles a bit, with the light spot describing a larger circle, the moveable weights will travel to that spot making the large circle, and balance the wheel in the process.

Putting the wheel on your motorbike, and rolling along, it becomes clear that the balancing action only can take place if the wheel is allowed to bounce around a bit by the suspension. If there is no bounce, the wheel will always be forced to rotate around the axle. But if the axle is mounted with enough 'give' the center of gravity will try to follow a smooth path, making the light side of the wheel describe slightly larger circles and the heavy side smaller ones. Objects inside the tire will 'fall' or travel towards the spot making the largest circle, and in doing so reduce the imbalance.

So far it didn't matter whether you imagined a flat 2 dimensional object or a real 3D one, with some width. But now imagine that the heavy spot on your wheel is off to one side of the rim. That spot will try to follow the smallest circle, and the point diametrically opposite, half way around the wheel and on the other side, will try to follow the larger circle. (The wheel, like any body, wants to rotate around the axis with the largest moment of inertia, which in this case is not parallel to the axle.) But a normal motorbike suspension will not let it do that. It will keep the axle parallel to the ground, and not allow the wheel to rotate the way it 'wants to'. That's why the objects inside the tire cannot balance a wide wheel that might require different weights placed on the left and right side (or inside and outside, on a car) of the rim.

I hope this helps. If you have difficulty visualizing the out of balance wheel freely spinning around its center of gravity, start with an odd shaped asteroid in outer space, or a stick with a rock tied to one end.
Click to expand...


Hmmm, I see it differently. The axle prevents the wheel from spinning freely around it's center of gravity. The centrifugal force on the heaviest part of the wheel is greater then the lightest part. Therefore the heavy side of the wheel has greater force on the axle. If the axle could move, it would move in the direction of the greater force, the heaviest side of the wheel. Therefore the heavy side would travel along a farther arc, not the lighter side.

Lets suggest I have 2 elastics of equal length and strength. I tie a 1 ounce weight on one elastic, and a 5 ounce weight on the other. I swing each elastic one at a time, but each one at the same speed with my hand. Which weight will pull harder on my hand and stretch the elastic further? The elastic with the 1 ounce weight, or the one with the 5 once weight? Which weight will have to travel a longer arc?

It seems to me that the only way those beads get to the lighter side of the wheel is due to their own free will!
 
Gruesome said:
I think the dynabeads explanation is pretty bad. I'll try to give a better one.
Click to expand...

Hi Gruesome:

I see a problem with your analysis.

Since there is no axle mounted in your "freely spinning", "out of balance" wheel, there is no geometric center reference. Your wheel is actually in-balance, rotating around its center of mass just like any irregularly shaped object would.

The beads require an "error" between the CoM and the axle center which causes vibration, in order for the beads to be forced towards the light side of the wheel/tire assembly.
 
lkraus said:
How do they work?
The basic principle behind how Dyna beads work is based on Isaac Newton's First Law of Physics - The law of Inertia. It states that a body at rest will tend to stay at rest. When there is a heavy spot on a wheel/tire, it tends to make that spot move away from the center when the wheel spins.

As I understand this statement, the heavy spot stretches the spinning tire so the radius might be slightly greater at that point. But then I imagine myself in a tiny hamster ball rolling inside the tire, and that greater radius looks like a dip in the road, a perfect spot to settle. The light spot, closer to the axle, is more of a hilltop, and not a very stable point to take a rest.

This is the exact opposite of the desired result.

Pending a more rational explanation, I think I'll stick to my Parnes balancer and some weights.
Click to expand...

people won't believe your explanation, but they were for big rig trucks originally and a better mouse trap will always come along.:hungover:thumb static balanceing is proven to work if done properly. Nobody needs to place foreign objects inside their tires.
 
Liquid beads:whistle Another balancing AND sealing option

My brother and his Victory riding friends use this stuff and claim...wait for it...

VICTORY:laugh:laugh:laugh

If it works for them, fine, I used SLIME in mountain bikes with some sucess but could throw a tube away with little mess involved.Have a feeling the tire guy at the Victory dealer is less than thrilled.

Cannot get youtube to load right on this tablet this morning...it is a 15 minute demo

Ride-On Tire Sealant = Indestructible Tires! (alm?: http://youtu.be/YqkBfEHYzxw
 
BJS, you are absolutely correct. If your suspension is not working, and the bike forces the axle to stay fixed, balancing can not take place. As soon as you allow a little bit of freedom for the wheel (springy suspension & tire), there will be a component of motion like I described above, and self-balancing will set in.

MM, I think most people would not call a wheel with an offset between center of gravity and axle 'balanced'. And I'm sure you wouldn't perceive it as such.

I'm not sure one can go much further without throwing in a bit of math. For a start, you could google 'general solution forced harmonic oscillator' to read about superposition of solutions and stuff like that.
 
Just doing some housekeeping and moving this to Gear. Since it isn't just an Oilhead type discussion.

And some of y'all are getting way over my paygrade with the physics:hungover :laugh
 
Gruesome said:
Putting the wheel on your motorbike, and rolling along, it becomes clear that the balancing action only can take place if the wheel is allowed to bounce around a bit by the suspension. If there is no bounce, the wheel will always be forced to rotate around the axle. But if the axle is mounted with enough 'give' the center of gravity will try to follow a smooth path, making the light side of the wheel describe slightly larger circles and the heavy side smaller ones. Objects inside the tire will 'fall' or travel towards the spot making the largest circle, and in doing so reduce the imbalance.
Click to expand...

I re-read your post and think we're on the same page with this part^.

Let me state a few things with which I think we agree:
1/ An irregularly shaped object spinning freely will spin around its center of mass without vibration.
2/ An "out of balance" wheel/tire assembly spring-constrained by an axle at its geometric center will vibrate because it tends to rotate about its center of mass but is spring-forced to rotate about its geometric center. The "error" between both centers forces the beads towards the light side of the assembly.

Classic negative feedback at work.
 
I used them in my k1200RS tires. I put over 10000 miles on a set of Road Pilot 2 tires, and once hit 120mph coming through Montana on the way home from Salem national, two years back. She was just as smooth as a babies behind up to that speed, so I have to come in on the side of, "they work, and I don't care about the physics of how they work.....:)
 
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