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can we go deeper on Dyna Beads and balancing?

That is one of the infamous videos.

Here is the other.
This one is much more compelling because of the strobe stop action. As well, note this is a different company using the same principle in a different way.

IMO these 2 videos together should be enough to convince anyone of the physics involved.


Thanks Mike! That is interesting, I hadn't seen that one before.
 
I'd like to see Mythbusters take this on one. They do some stupid stuff lately, and this one is a good one.
 
Put an axle through the wheel. In the case of the rear wheel on a modern BMW you need an adapter so the axle is centered. Both ends of the axle fit in bearings. Suspend the bearings far enough off the ground so the wheel spins freely. Let the wheel go and the heavy spot will sink to the bottom. Rotate the wheel about 1/4 turn and watch the heavy spot sink to the bottom again.

Here I am checking the wheel sans tire using the Marc Parnes balancer and an older version of his rear wheel adapter. Some tires come with a colored dot which marks the light spot on the tire. You match that with the heavy spot on the wheel which is assumed to be the valve stem. Notice where the valve stem is in this picture.

p-20090724-1441-5466.jpg


On this wheel the valve stem is the light spot. Interesting. But then these days fewer and fewer tires are marked with the dot so the actual location of the wheel heavy spot isn't so important, I guess.

Balance is done by adding weight to the light spot (the top when the wheel stops). When you've got the right amount the wheel will stop in random spots when given a gentle spin. The balancer is good enough in practice that you will not find the PERFECT amount of weight. You'll get it to where adding or removing 5 grams is enough to move the heavy point from one location on the wheel to another. That is plenty close enough.

I'll add that my balancer easily detects two grams of weight. If you are really patient, it will pick up 1 gram, but that level of accuracy is not needed.

Also, it is reproducible which is important. You always want to double check for reproducibility by removing the balancer setup, putting it back on in a different orientation, and confirming no change. I find the static balancer is excellent, easier than the beads that I no longer use, and more satisfying to perform.

I also confirm the light spot, and it is always NEAR, but not really AT, the valve stem.

Marchy, I've heard about guys lightly grinding away at the rim to produce a perfectly balanced wheel with no tire. Seems a bit obsessive/compulsive to me. Have you ever calculated how many grams out of balance your bare wheel is? I keep meaning to do that, but never get around to it.
 
Just try it???

I know that there must be someone that would like to experiment. Who cares about theory?

Force a tire and wheel out of balance with weights, ride it and note the condition. Add beads to the unbalanced wheel and ride it again. Did it correct the out of balance condition or not?

That being said, it needs to be somewhat reasonable test. By that that I mean you can't throw a wheel out of balance by 6 oz and expect 3 oz of beads to fix it.

I would think that someone could have feedback on this by the end of the day and finally put this issue to bed!
 

Marchy, I've heard about guys lightly grinding away at the rim to produce a perfectly balanced wheel with no tire. Seems a bit obsessive/compulsive to me. Have you ever calculated how many grams out of balance your bare wheel is? I keep meaning to do that, but never get around to it.

My BMW rim sucks with respect to balance. I'm not even sure it meets BMW specs but I didn't realize that until long after the warranty period had passed. Anyway.... after enough tire changes I realized I was often putting the same number of weights at the same location as the ones I'd removed with the old tire. Then I made matters worse by adding in internal tire pressure monitor.

My solution was to balance the wheel with tire pressure monitor installed. It required 70 grams of added weight without tire. I still check the balance after mounting new tires. Most of the time the wheel is well enough balanced I need add no more weight. Sometimes I have to add another 5-15 grams someplace or another.

I've ground down parts of pistons to get a matched pair, but never wheels.
 
Yes, I had suggested this before, and said I'd do it on my next tire change. But I always seem to be in a hurry and need my tires asap! Also, the beads became all clumpy and nasty with rubber bits, so I just tossed them out and went back to the tried, true, and cheap static balance.

For this test to be scientifically meaningful, the rider should ride the bike on the same course about 6 times: 3 in balance, 3 out of balance, and he should not ever know which condition the bike is in until he has reported his thoughts on all the rides to avoid the placebo effect.

It would be a good test.

Also, I bet it would take a lot of weight to make a wheel out of balance enough to be noticed on the street. An ounce at least, I bet. Now that is a test I should try.
 


That is one of the infamous videos.

Here is the other.
This one is much more compelling because of the strobe stop action. As well, note this is a different company using the same principle in a different way.

IMO these 2 videos together should be enough to convince anyone of the physics involved.

You can also see the physics up close and personal if you put some clothes in your top loading washer and watch how it works on the spin cycle.

It's interesting that some people think for dynabeads to work they would have to defy the laws of nature, but those same people most likely wouldn't think there's anything abnormal about how a washing machine tub stays balanced during the spin cycle.
 
You can also see the physics up close and personal if you put some clothes in your top loading washer and watch how it works on the spin cycle.

It's interesting that some people think for dynabeads to work they would have to defy the laws of nature, but those same people most likely wouldn't think there's anything abnormal about how a washing machine tub stays balanced during the spin cycle.


Well said. Static and dynamic balance are two very different animals. What does dynamic balancing make possible -- jet engines, high performance helicopters, one popular brand of aircraft high output reciprocating engines uses swinging crankshaft counterweights, and yes, washing machines. Our bike tires probably fall somewhere between these extremes.
I static balance - why, because it is generally good enough, but one cannot argue about the effectiveness or physics of dynamic balancing.

Bokrijder
 
That's never gonna happen. This topic will always be "an oil thread".
Here's your lullaby on beads: They are cheap(I have a huge bag for $20-call it a lifetime supply) and can be installed easily/quickly & reused(mine get black but not lumped or unusable), can be installed/reinstalled at my house-not some remote dealer/shop on their time schedule and me paying for something that falls off or fails to correct the constantly changing balance dynamic(carrying weights around doesn't fix a constantly changing tire weight!) & they don't pollute the environment. I dare you to read up on the amount of wheel weights that enter the roadway! And another tidbit: after 1,000's of miles they are happily kicking around in there doing the job...:lurk
Honestly the hardest part is the tapping the install tubing with a screwdriver as they try to cling to their buddies before entering their black tire prison. Static cling makes for a slow but lazy few minutes.
I did a quick search on OEM wheel balance/runout specs but failed to get to the heart of it. I would think that in practice a "good but used" wheel is more likely to have runout than out of balance, but thats a guess. Tires being handmade circles are the seemingly imperfect aspect of that senario and given that they wear unevenly become more out of spec. Unless bent a wheel is true and a constant.:lurk Oh, and it's raining here again for the , well, I've lost count # of days...
 
I static balance - why, because it is generally good enough.

Bokrijder

I agree. Marchyman figures he gets to within a few grams. There's a lot of other vibration going on and no point in whipping a dead horse.

Mostly I'm chiming in now to thank you guys for honest meaningful posts. It's all about getting this sorted one way or the other without mindless trash talk.

Thanks for making this the best Dynabead thread in which I've participated!
There have been a few.
I have some scars.
 
I would think that...by the end of the day...finally put this issue to bed!

It's hard to do when everyone wants to be right.

Bottom line is to just try them. They're easy enough to put in.
If you don't see/feel any difference dump 'em on the next tire swap.

Waste of time and energy arguing over them. Just try 'em and end the mystery.

Some good explanations/images given here.


DB-5.jpg



Take a look:


http://www.bestrestproducts.com/c-100-dyna-beads.aspx
 
Going to try 'em!

I washed my bike last month, one Saturday afternoon. On Sunday morning I noticed a wheel weight lying in the driveway!!:banghead Dang!!! I suspect I'm not the only one to have this experience......right?

Seems like most folks posting about their experiences with DynaBeads almost always have something positive to say, so I'm going to give 'em a try. I'm guessing they can't be worse than wheel weights that come off in the wash. If they are, I'm only out a few bucks and a few hours to pull the tires and remove them.
 
You can also see the physics up close and personal if you put some clothes in your top loading washer and watch how it works on the spin cycle.

It's interesting that some people think for dynabeads to work they would have to defy the laws of nature, but those same people most likely wouldn't think there's anything abnormal about how a washing machine tub stays balanced during the spin cycle.

Good lord my washing machine will vibrate so badly it will walk across the floor and unplug itself. :scratch Only when in the spin cycle OK at slow speeds. I would expect some damnping of vibration with the beads but seems to be a dynamic solution to a static problem. :lurk
 
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I washed my bike last month, one Saturday afternoon. On Sunday morning I noticed a wheel weight lying in the driveway!!:banghead Dang!!! I suspect I'm not the only one to have this experience......right?

Seems like most folks posting about their experiences with DynaBeads almost always have something positive to say, so I'm going to give 'em a try. I'm guessing they can't be worse than wheel weights that come off in the wash. If they are, I'm only out a few bucks and a few hours to pull the tires and remove them.

The one in your driveway is a small part of the 12.5 million pounds that don't get recycled each year!Not to blame your one weight for anything. Google "lead wheel weights in the environment" for a real eye opener! Using lead weights in NY state is a $1000 fine as of now. I have tried to state this many times but it isn't hitting home: lead weights have to go. :deal:deal:deal:deal:deal:nono:nono:nono

I too am trying to be positive and say they have to go and beads are a way to do that-even better see if the tire even needs weight!
 
" I would expect some damnping of vibration with the beads but seems to be a dynamic solution to a static problem." :lurk


OH,

You have hit the nail on the head, albeit in a twisted way.

Allow me to play with your statement. "Dynamic balance solution to a static balance problem." Static balance problem ?? -- only when the bike is standing in the driveway.

Inverted to accurately describe tire and wheel static balancing

"Static balance solution to a dynamic balance problem."

This is what we are doing when we static balance a tire.

Why is it a dynamic balance problem - because the bike tires are spinning when in use. Dynamic balance is rotational balance. However we static balance because it is quick, cheap, easy, and chiefly "Good enough".
If we were to consult Mr. Newton, he would tell us that we are doing it all wrong, but that's OK as most don't mind getting "one over" on Mother Nature.

Dyna Beads simply play by Mr. Newton's rules. Dynamic balance solution for a dynamic balance problem. Ever see a high tech spin balancer at a tire shop? That's a dynamic balancer. Even this high tech machine is a compromise as the technician attaches fixed weights. Why a compromise? - perfect dynamic balance is tied to a specific RPM. At every RPM a slightly different weight placement is required.

Hmmmm - what we really need is a movable weight mass which would automatically move to the proper location throughout the desired operating range.
Slowly turn a fan jet engine -- what's all of that rattling, jingling, and jangling? Sounds like bucket of bolts. Must be something loose in there, but when it is running - smooth as silk, Hmm. Dynas free to move in the tire, Hmm
Why or how? For the sake of this post, "PFM" Pure F ---- Magic!! I'm sure that's what many said when Isaac first put forth his ideas. " Isaac, that's got to be PFM!!"

That's that, if they are difficult to install, clump, irritate, stick or cost too much - that's another topic.

Please excuse me, I'm short on time. I've got a pair of tires to mount and static balance.

Bokrijder
 
OH,

You have hit the nail on the head, albeit in a twisted way.

Allow me to play with your statement. "Dynamic balance solution to a static balance problem." Static balance problem ?? -- only when the bike is standing in the driveway.

Inverted to accurately describe tire and wheel static balancing

"Static balance solution to a dynamic balance problem."

This is what we are doing when we static balance a tire.

Why is it a dynamic balance problem - because the bike tires are spinning when in use. Dynamic balance is rotational balance. However we static balance because it is quick, cheap, easy, and chiefly "Good enough".
If we were to consult Mr. Newton, he would tell us that we are doing it all wrong, but that's OK as most don't mind getting "one over" on Mother Nature.

Dyna Beads simply play by Mr. Newton's rules. Dynamic balance solution for a dynamic balance problem. Ever see a high tech spin balancer at a tire shop? That's a dynamic balancer. Even this high tech machine is a compromise as the technician attaches fixed weights. Why a compromise? - perfect dynamic balance is tied to a specific RPM. At every RPM a slightly different weight placement is required.

Hmmmm - what we really need is a movable weight mass which would automatically move to the proper location throughout the desired operating range.
Slowly turn a fan jet engine -- what's all of that rattling, jingling, and jangling? Sounds like bucket of bolts. Must be something loose in there, but when it is running - smooth as silk, Hmm. Dynas free to move in the tire, Hmm
Why or how? For the sake of this post, "PFM" Pure F ---- Magic!! I'm sure that's what many said when Isaac first put forth his ideas. " Isaac, that's got to be PFM!!"

That's that, if they are difficult to install, clump, irritate, stick or cost too much - that's another topic.

Please excuse me, I'm short on time. I've got a pair of tires to mount and static balance.

Bokrijder

I was thinking, in balance is in balance. Problem with static balance is it would drive you crazy trying to balance the tire in quadrants a la computer spin. My understanding of the computer spin balance is it spins the tire so the machine can read where it is out of balance. Although all the ones I have used you usually never end up with more than 3 weights usually 1 sometimes 2. It is the PFM in the computer sensors that make or break the thing. Old manual spin balancers were more of a 1 position deal, spin again see if you could make it better. Sometime just slam a weight on somewhere to try to get it close enough for the thing to stop shaking. But my thinking is balance does not change static or dynamic with the exception that most spinning things have a critical speed ( whole nother animal that is ).

What is the phrase Pothing is Nerfect. :ear
 
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