Science of Balancing Beads

[Andrew Shadow]

A debate about whether balancing beads work or not based on personal experience is not my goal here. There are many threads already where these anecdotes can be posted.

I have an intellectual curiosity as to the physics of how they work. From what I have been able to find it seems that there is some scientific support that they can reduce vertical imbalance. They cannot correct lateral imbalance from what I understand but then again neither can a static balancer- only a dynamic balancing machine can do that. Considering that the rims on motorcycles are fairly narrow lateral imbalance is most likely not a significant concern anyway unless the rim is bent- which is a different problem entirely.

I admit to not being the most efficient at locating specific information on the internet. I often end up frustrated because I find everything except what I am looking for.
As such, I have not been overly successful in finding information that relates specifically to the physics principles behind how these products successfully balance a rotating mass. If you look in to the science behind static and dynamic balancing techniques, explanations of the physics behind each can be found. Most of what I find in regards to balancing beads seems to be designed more as a marketing tool. They rarely go beyond statements saying that the rotation distributes the beads to where they need to be. This is rather superficial as would be expected for marketing purposes. But does physics support that claim?

Here is an example of the type of things I have found- Dyna Beads: Miracle Balancing Cure or Tire Snake Oil?
Even though the author seems to be less than overly enthusiastic about the effectiveness of balancing beads, there is no detailed scientific explanation of the muted claims that he does make?

If anyone has come across actual scientifically conducted tests or explanations that go a little deeper in to explaining how these work to balance a rotating mass, or don't work for that matter, other than the marketing claims made by the manufacturers themselves, I would appreciate any links to them that you may be able to provide.

As an aside I came across the below while poking around the internet. Apparently this principle for balancing wheels has been around since the early seventies at least. I guess this adapter was the precursor to balancing beads. I thought that I would throw it in just for the interest factor. It illustrates that the idea of balancing beads is by no means new. They don't seem to have one available for the ST1300.
CENTRAMATIC

 

[sfalexi]

Maybe?

 

[heffly]

 

[ST Gui]

I have two car tire balancing items similar to the Centramatic pieces. I never got round to installing them and don't know if they'll fit my current car. I got them from some car accessory mail-order place - possibly Sharper Image or some other equally suspect source of automotive gee-gaws.

I think the version I have was designed to fit between hub caps and steel wheels and not between the wheel and hub. Maybe thats why I never installed them. Pity as they might actually have worked.

The beads & bottle vid has been posted before and it convinces me as does the Centramatic video of the effectiveness and how they work but not the 'why'.

Somebody somewhere must have considered some scientific principal to think a mobile mass inside a tire would smooth an eccentric motion of imbalance. I suppose it's possible someone got a weighted plastic bottle and had fun watch it wobbling around. Then they thought 'for no reason what so ever let me put some small bit in it. Or maybe they were trying to construct a celebratory noise maker. The bottle's rotation smoothed and they thought 'This would make a great tire balancing tool!'

Obviously centrifugal force and eccentricity of a rotating mass are part of the 'why'. But how that explains the 'why' I dunno.

 

[Daboo]

I'm also in the camp of not knowing exactly why it works...only that I've seen things I can't explain any other way than that it does work.

Ride-On also makes a claim that their product balances the tire as you ride. I noted that Slime does not make that claim. Perhaps because over time, the Slime becomes tacky and distributed on the inside of the tire's tread area. It would have to stay liquid in order to flow from one place to another.

A quandry I'm going through is that if I put in balancing beads in the rear tire, I can't use Ride-On or Slime for a tire repair later without removing the beads. So with a bottle of Ride-On available and a couple ounces of Balancing Beads...which do I use? Hmmm... I'll probably change my mind several times between now and when I change the tires.

Chris

 

[MaxPete]

My vintage bike group has asked me to give a series of technical lectures because I have some technical training (doctorate in Mechanical Engineering) plus industrial consulting. I sure don’t know everything, but I do know a few things. Topics have included threaded fasteners, rolling element (ball & roller) bearings and journal or plain bearings, etc.

They asked me most recently to explain these “balancing beads” and try as I might....I simply couldn’t. The adverts are full of utter nonesense wrapped in an impenetrable sheath of techno-babble baloney and so I stopped reading them (they are worse than a 1960-70s Japanese motorcycle manual). I switched over trying to work it out myself from first principles, and I simply cannot come up with a plausible explanation of how these substances function to”automatically” balance a tire & wheel assembly.

What they all do seem to achieve is that they make an awful mess inside a tire which makes it nearly impossible to repair later. I also noted that NONE of the tire manufacturers and NONE of the motor vehicle OEMs (bike/car/truck etc.) that I checked with recommend them.

Sooooo, I’ll be sticking to wheel weights myself. They’ve been doing a fine job for a hundred years or so.

Just because somebody makes something and advertises that it does something....doesn’t mean that it is true.

Pete

 

[SMSW]

Andrew, I, too have wondered about this. I also admit to being turned off by the heavy marketing programs that say 'trust me'. Whenever somebody who purports to be impartial (other than the vendors) tests these things, they report inconsistent results. I believe Consumer Reports may have tested one of these products years ago, and MCN similarly said they were not as reliable a way to balance mc wheels as standard exterior weights. Some years ago my mechanic (who swears by little packets of a similar product that he threw into my tires before mounting them) installed one of these systems on my GMC truck. Three or four years later, when the tires were junked, I inspected them as they came off the rims. There was nothing inside, despite having seen him put said packets into each wheel. Where did the powder go? There were no obvious lumps or deposits inside the tires and a wipe w/ my fingers produced very little dust. I confess to being skeptical about the claims.

 

[SMSW]

They asked me most recently to explain these “balancing beads” and try as I might....I simply couldn’t. The adverts are full of utter nonesense wrapped in an impenetrable sheath of techno-babble baloney and so I stopped reading them (they are worse than a 1960-70s Japanese motorcycle manual).

Pete, is that a known engineering term (boldface)? I should object to someone maligning a food I once ate, but since I quit eating it once I found out what went into the 'sausage', I'll keep my mouth shut.

 

[MaxPete]

Well....this is a family site SMSW so I couldn’t use the ACTUAL term we, in the profession, normally apply to overblown late-night TV hyperbole. As I said, I don’t know everything, but I do know that what these folks say about their own product is nonesense.

Just watch one of those miracle oil additive infomercials or the absolutely hilarious one where the guy installs this thingamajig that “electronically aligns the molecules in your fuel” to improve fuel economy - and you’ll get the idea.

 

[Kevin_56]

What they all do seem to achieve is they make an awful mess inside a tire which makes it nearly impossible to repair later.

Having used beads in the past on my 1300 for several sets of tires. Never experienced an unbalanced "feel" even at illegal speeds. Never saw any "mess" in the carcass of these tires. There was some rubber dust, but nothing to be concerned, in my opinion. If you have used them and have seen a mess, then you can state that. If not you are second hand quoting. As far as impossible to repair, repair what, you are replacing the tire. To repair a puncture, they grind the devil out of the inside b4 patching, that creates a mess.

How do they work, I have no idea. Do they work, for me i felt my tires were in balance the entire life of these tires. Do I still use them, no. Not because I do not trust them, I ran out and inherited a balancer and weights. Cheap, I am, using what was and is free.

I used a nylon stocking over a shop vac hose to vacuum the beads out of the tire once I got the first bead off the rim. This trapped the beads in the stocking. I then poured them back into the new tire from the stocking. Worked for me and no beads on the floor to slip, slide on.

 

[ST Gui]

Just because somebody makes something and advertises that it does something....doesn’t mean that it is true.

And a corollary might be - just because we don't believe in something or it's advertising that it does something....doesn't make it false.

So far we have two methods of balancing wheels — one tried and true well accepted and easily explained and another that by almost all anecdotal evidence does work as advertised with little or no proof to the contrary and yet seems to defy explanation.

Arthur C Clark has it right -

any technology sufficiently advanced is indistinguishable from magic..

And magic once explained - is not magic

Less known/used is one of my favorites:

Every revolutionary idea seems to provoke three states of reaction.
They may be summed up in three phases:

1. It's completely impossible.
2. It's possible but it's not worth doing.
3. I said it was a good idea all along.

Around here we could include 2b) I'd be concerned... Or not 2b. That could be put anywhere on the list.

At this point I think it's clear the beads work. We still don't know why and even if we did we all make our own choice.

 

[MaxPete]

Well, I’ll bow out now and leave these thoughts:

1. I don’t know if or how the beads work - and based on my reading of the adverts of the folks who make them, they don’t know how the beads work either. However, as you say Robert, wheel weights do work and any Grade X high school science student can explain why.
2. The tire makers and vehicle manufacturers do not recommend them, and that seals deal for me.

Cheers,

Pete

 

[heffly]

Ekman Layer, hydrostatic and Coriolis effects for hydraulics in centrifugal motion. It seems the outer layer, the heavy part (of a tire) creates a greater force because of radial distance, ie the further you are from the center of rotation the more force is developed. Thus there is a lower pressure zone inside of that circle. So the heavier outside force pushes material to the lower pressure zone until equilibrium is achieved, or balance. As I understand it.....

 

[Larry Fine]

Here's my explanation (translation) of what I was able to understand:

Suppose you laid an unmounted tire on the ground and put several golf balls inside, spaced around the tire. If you were to kick the tire away from yourself, the balls would move toward you as the tire moved away from you.

Likewise, when spinning, the heavy side pulls the tire toward it, leaving the balls to move toward the opposite side. Why the balls don't instead pool into the section of the tire farthest from the rotational center, I don't know.

 

[bdalameda]

If you think about how an out of balance tire will attempt to be thrown away from it's center on the heaviest point. The balance beads are fluid and resist the motion of the imbalance and counteracts that force - the greater the force applied by the imbalance the more the fluid or loose weight will counteract the force. One problem with using this type of balance system is that suspension movement also causes the wheel center to move when moving over road irregularities. This suspension motion will also cause the loose balance weights to counteract the suspension travel. This is why race vehicles don't use balance beads etc. as it causes problems with the suspension action.

 

[Larry Fine]

Read up some, and here's the simple explanation: Once above a certain RPM (different for every tire/wheel assembly), the assembly attempts to rotate around the center of its mass, which places the heavy point closer to the center of rotation, not farther from it. That leaves the light side farthest from the center, pushing the beads there.

Found these, in no particular order:

http://www.innovativebalancing.com/HowItWorks.htm

Post #5 and post #14: https://www.physicsforums.com/threa...product-dyna-beads-for-tire-balancing.637080/

 

[W0QNX]

I did notice that the beads move down the toilet in a similar direction as tornadoes circulate around a mobile home in Kansas when I tired them.

 

[Andrew Shadow]

and another that by almost all anecdotal evidence does work as advertised with little or no proof to the contrary and yet seems to defy explanation.

For every internet post of anecdotal evidence you can find stating that they work you can find another internet anecdotal post stating that they don't so neither claim carries much weight.

Ekman Layer, hydrostatic and Coriolis effects for hydraulics in centrifugal motion. It seems the outer layer, the heavy part (of a tire) creates a greater force because of radial distance, ie the further you are from the center of rotation the more force is developed. Thus there is a lower pressure zone inside of that circle. So the heavier outside force pushes material to the lower pressure zone until equilibrium is achieved, or balance. As I understand it.....

Having no familiarity with these principles I guess I have some reading to do.

Once above a certain RPM (different for every tire/wheel assembly), the assembly attempts to rotate around the center of its mass, which places the heavy point closer to the center of rotation, not farther from it. That leaves the light side farthest from the center, pushing the beads there.

Assuming the wheel assembly remained in a constant state from that point forward that might be plausible. Tires, especially motorcycle tires, are quite flexible and are constantly changing shape with every movement and with every road irregularity that they hit. Assuming this principle is correct this would mean that the beads would have to be in constant motion as they hunt for the tire's heavy point which is a constantly moving target. Regardless of how quickly all of that happens the beads would have to be in the wrong place as least as often as they are in the right place so the wheel assembly would have to out of balance at least as often as it is in balance. With a motorcycle there is the added elements not only of the tires changing shape as the they lean but also the directional forces changing with the lean. These forces also increase and decrease as the lean increases and decreases. What effect does that have on these principles? Maybe the impact during these transitional phases is insignificant enough as to not matter- I don't know.

The balance beads are fluid and resist the motion of the imbalance and counteracts that force - the greater the force applied by the imbalance the more the fluid or loose weight will counteract the force.

But why do they resist that force? Wouldn't centrifugal force just push the beads against the inside surface of the tire, keep pushing them until they were no longer piled up against each other and could go no further and then just hold them there? I don't understand why they would then continue to move and end up in specific locations where they needed to be to achieve a balance point. I guess I have more reading to do to understand this.

I did notice that the beads move down the toilet in a similar direction as tornadoes circulate around a mobile home in Kansas when I tired them.

I take you are a non-believer then!

 

[Andrew Shadow]

I thought of an analogy that may or may not be salient.

If I told someone that I can fill a glass with water to a height higher than the top rim of a drinking glass they might not believe me. If I then did this for them and they see with their own eyes that the water level is definitely above the top of the rim of the glass and no water is being spilled they would believe it. They would believe and accept it but they would not understand why it can be done. If I then explained to the them the principle of surface tension and how surface tension makes this possible they would then not only accept it but they would also understand it.

Overflowing Surface Tension

This is the gist of what I am after. I don't want to simply drink the cool-aid- I want to know how it is made.

 

[Andrew Shadow]

My vintage bike group has asked me to give a series of technical lectures because I have some technical training (doctorate in Mechanical Engineering) plus industrial consulting.

Well, I’ll bow out now and leave these thoughts:

Don't leave just yet Pete. Hang around for a while longer. Your training and expertise sound like what I need, some sharp minds, to help me understand this because I don't get it yet.