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Easy_rider
| | Posted on Tuesday, June 22, 2010 - 09:31 pm: | 
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No idea how you conclude that. You could mount them to the fork lower and they could damp vibration just as well. How would that balance the wheel/tire?
Unless your fork lower is spinning around in circles I wouldn't expect it to.
My HVMP bar ends dampen the vibrations I feel in the handlebar, does that mean it balances the bars?
Noooo.... they aren't vibrating due to an imbalance in the moving assembly. |
Sifo
| | Posted on Tuesday, June 22, 2010 - 09:39 pm: |
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Blake, what makes you say that they simply dampen vibration? Is from the added mass? You would have to add a lot of mass to make any difference you could feel.
The video with the wheel barrow wheel does show the beads moving opposite the magnet that was added to imbalance the wheel. That is pretty good proof that there is something to it.
Having said that, I don't think it's the ultimate solution. In addition to the limitations I theorized earlier I think there would be issues under hard acceleration and braking as the beads would tend to roll from inertia. |
Blake
| | Posted on Wednesday, June 23, 2010 - 01:04 am: |
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"Unless your fork lower is spinning around in circles I wouldn't expect it to."
You'd expect wrong then.
When it comes to damping, all else being equal, the cause of vibration is irrelevant; the damper doesn't care whether vibration is due to an imbalance or an external input.
Tom (Sifo),
Every great con has a very convincing hook. The vibration damper that the wheel barrow wheel demonstration employs lessens the vibration, but it certainly doesn't eliminate it.
Scrutinize and analyze...
Review the demonstration at approximately 30 seconds into the video where the host comments that the wheel/tire assembly "is a little bit out of balance."
Yet note that very little, almost an imperceptible amount of vibration is evident including in the base of the fixture.
Now review at 1:55 when the host is imploring you to "notice how smoothly it is turning." The base of the fixture is vibrating like crazy.
A balanced wheel/tire assembly won't vibrate like that, it will be perfectly smooth, like shown at the 30 second interval.
It's a vibration damper. They even say so when discussing the fluid; they call it "dampening fluid". It more accurately should be referred to as "damping" fluid. 
"Centramatic, the world leader in balancing technology"? Please.
Look up the physics involved in a "tuned mass damper".
Incredibly simple. |
Blake
| | Posted on Wednesday, June 23, 2010 - 01:08 am: |
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Damping on truck wheel/tire assemblies is a perfectly valid means to improve tire life absent periodic balancing. It doesn't balance the wheel/tire assembly. It just reduces the vibration for an imbalanced assembly. |
Sifo
| | Posted on Wednesday, June 23, 2010 - 08:34 am: |
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Blake,
You may have missed earlier when to pointed out those same things about the demonstration. I also point out that it will never lead to a perfectly balanced wheel, as demonstrated in the video.
You still haven't answered my question though, what is the source of the vibration damping? I just don't see it.
I think the damping (dampening) fluid is more to keep the beads from sloshing around like water in a bowl when accelerating or braking, not damping vibration from the out of balance condition. This would be a feature missing in the Dyanbead system whatever it does. |
Sifo
| | Posted on Wednesday, June 23, 2010 - 09:36 am: |
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So what are the physics involved in Dynabeads? Let's take a look using a simple diagram of a wheel.
A wheel will rotate around the center of mass. That is simple physics. A balanced wheel will rotate around the axle or point A in the diagram. However if the wheel has a heavy side at point B the center of mass moves toward point B. The out of balance wheel now will rotate around point C. I have it exaggerated a bit just to make it a bit more clear.
So what will happen to beads that are free to roll around inside the tire? The will try to get as far from the center of rotation as possible. Again this is simple physics. When the center of rotation is at point C the beads will want to go to point D. This will move weight to point D balancing the wheel.
As I said earlier in this thread I think this will never produce a perfectly balanced wheel. Also under acceleration or braking the beads will likely shift from these forces causing the wheel to be temporarily out of balance. Adding a fluid will help to damp this effect, but the Dynabead system doesn't do this.
Comments? |
Spiderman
| | Posted on Wednesday, June 23, 2010 - 10:06 am: |
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OK here is a simple truth that will tell you weather or not Dyna beads are effective or whether or not they really do balance a wheel...
In a manufacturing environment the faster and cheaper something is built/assembled the better. Therefor they are always streamlining things, like sub assembly sections, automation, ETC.
So
When it comes to the wheel sub assembly station in the current state they have to mount the wheel, balance it, put the weights on, re-balance to make sure it is good then pass it on.
In that situation you are paying labor to mount a tire, run a wheel twice, and the price of weights.
Dyna beads will consist of mounting tire, then filling with beads.
So as you can see if the beads worked all manufacturers would have been using this for a while now...
For Dyna Beads the |
Sifo
| | Posted on Wednesday, June 23, 2010 - 10:26 am: |
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The procedure for adding the beads as I understand it is to fill through the valve stem after seating the tire on the rim. Just guessing here but is there a problem with them getting between the tire and rim if you cheat by just dumping them in first? I understand that it's pretty tedious getting them to go in there without clogging. Also aren't the beads fairly expensive to begin with?
This is a case of do the economics make sense as well as do they work. They may work but still not make economic sense. |
Daggar
| | Posted on Wednesday, June 23, 2010 - 11:17 am: |
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Not to mention the mess and safety issue if beads are spilled. |
Spiderman
| | Posted on Wednesday, June 23, 2010 - 11:38 am: |
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The procedure for adding the beads as I understand it is to fill through the valve stem after seating the tire on the rim.
Yes re-read what I said, "Dyna beads will consist of mounting tire, then filling with beads. "
I understand that it's pretty tedious getting them to go in there without clogging. Also aren't the beads fairly expensive to begin with?
6 oz back is $11.50
Wheel weights are $14 for 9 oz
these are retail prices for small amounts, not bulk pricing for let's say a factory...
And that is not including tax, delivery nor the labor for tire mounting etc...
Also once they start using it they will standardize an installation.
Not to mention the mess and safety issue if beads are spilled.
Seriously? Lead, battery acid, gas, chemicals, moving parts, HiLo's running around, pneumatic lines and tools, ETC and dynabeads are a safety issue!? LOL
(Message edited by spiderman on June 23, 2010) |
Natexlh1000
| | Posted on Wednesday, June 23, 2010 - 11:39 am: |
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How about just a handful of golfballs when the bead is opened?
That should be enough mass to work  |
Mr_grumpy
| | Posted on Wednesday, June 23, 2010 - 11:55 am: |
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Is the weather too bad to ride there?
My excuse is I'm at work. |
Sifo
| | Posted on Wednesday, June 23, 2010 - 12:05 pm: |
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So if they need to get the beads through the valve stem, it becomes a tedious process that doesn't lend itself to an assembly line. You give prices for lead and beads, but no means to compare them. The question is what is the average cost per tire for each system.
None of this addresses if they will balance a tire though. |
Spiderman
| | Posted on Wednesday, June 23, 2010 - 12:12 pm: |
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So if they need to get the beads through the valve stem, it becomes a tedious process that doesn't lend itself to an assembly line.
A lot of things we do on our bikes seems tedious, but they manage to make it fast on an assembly line no?
If the beads worked they would make installation work fast...
They fact that no manufacturer uses them as OEM proves that it is not a viable means of balancing a tire.
But it did take a bit for OEM to catch up to the synthetic trend on Hi Pro bikes...
The only real proof will be someone taking a tire, putting it on a balancer. balance it with lead weights, then remove and insert the beads and see what the balance machine says... |
Sifo
| | Posted on Wednesday, June 23, 2010 - 12:18 pm: |
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The only real proof will be someone taking a tire, putting it on a balancer. balance it with lead weights, then remove and insert the beads and see what the balance machine says...
Or if a bead user would add enough weight to a wheel temporarily and go for a test spin. Someone already established that about 2 oz. is enough out of balance to tell it's out of balance. It's a real easy test for the true believer to do. Will anyone take up the challenge? |
Daggar
| | Posted on Wednesday, June 23, 2010 - 01:08 pm: |
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I just meant at a shop, if the beads spill, that's going to be a hazard that has to be dealt with immediately, I would think. Seems like it would be a major slip hazard.
I've been going back and forth on trying Dyna Beads. They're cheaper than a Parnes balancer but they seem too good to be true. |
Sifo
| | Posted on Wednesday, June 23, 2010 - 01:25 pm: |
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6 oz back is $11.50
Wheel weights are $14 for 9 oz
I just checked my mini-van. 3 tires had .75 oz and one had 1.5 oz. Total of 3.75 oz of weight. Let's say 4 oz is typical. That's less than $6.25 in lead using your quoted cost.
Dynabeads require 3 oz of each wheel of that size. That's a total cost of $23 to balance those same tires.
That's a cost difference of $16.75 per car in the materials. I doubt the cost of assembly line balancing is very high per wheel. I'm sure they bang one out every couple of minutes or less. I'm guessing the cost factor still would give the advantage to traditional balancing, even if they found a way to inject the wheels with beads reliably. |
Kenney83
| | Posted on Wednesday, June 23, 2010 - 01:41 pm: |
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i have had the dyna beads on my last set of tires and this set. my last set where michelin pilot powers, this set are shinko ravens. i have had no problems with them, even with speeds up to 120 mph. i like them and will continue to use them. i like how i don't have wheel weights on my tires. cleans them up a little bit. this is just my opinion.
kenney |
Sifo
| | Posted on Wednesday, June 23, 2010 - 01:45 pm: |
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Would you be willing to stick about 2 oz of weight on a wheel and run it up to highway speeds as a test guinea pig? Someone needs to step up to the plate on this! |
Blake
| | Posted on Wednesday, June 23, 2010 - 03:21 pm: |
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Tom,
Your mental experiment is flawed. By your explanation, the beads require an imbalance in order to move them to the required position inside the tire, where they then supposedly balance the tire. Well, then you've just lost the only mechanism (imbalance) that puts the beads in the proper position. Accelerate, decelerate, hit a bump, turn, heck even just the cyclic interaction of the tire contact patch flattening as it encounters the pavement every rotation would send the beads quickly away from their optimum magic balance position.
All you need to do is watch the video and note what I pointed out. The "balancer"--really a damper--does NOT balance the wheel assembly. It only reduces the vibration, and it doesn't eliminate the vibration. There is still significant vibration there.
You keep insisting that someone perform your test scenario. I keep telling you that it is insufficient to demonstrate whether or not the wheel assembly is balanced.
I don't know how else to describe it. |
Blake
| | Posted on Wednesday, June 23, 2010 - 03:31 pm: |
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The source of vibration damping is added mass and viscous fluid. The added mass reduces the natural frequency of the assembly and the visco-elastic connection of that mass to the assembly provides damping.
Note that all the demonstrations for these so-called balancing products always employ a HUGE imbalance. In reality, that is rarely if ever the case. In reality, the imbalance is mere ounces or portions of an ounce. In reality, the wheel/tire assembly doesn't vibrate very much at all.
What problem does that present for magic balancing beads?
Not enough impetus to move anywhere in the tire to achieve balance.
The beads provide damping in the same fashion as tuned mass dampers. Google it. |
Sifo
| | Posted on Wednesday, June 23, 2010 - 03:33 pm: |
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Blake,
I think we are pretty close to agreement here. I pointed out long ago that the beads would never achieve perfect balance, for the exact reason that you point out. Unfortunately the same argument can be made with dynamic balancing. You can only work within the tolerances of the tools you are using, it will never be perfect.
My question is... Are the beads good enough that you don't notice the imbalance? It means little to me that people are using the beads and don't have problems when people are using unbalanced wheels and not having problems. I am interested in if the beads will take an imbalanced tire and smooth it out to where you don't notice in real world conditions.
I have mentioned every condition that you just mentioned except for hitting bumps and turning. Personally I'm staying with dynamic balancing, but I have an honest intellectual curiosity in knowing it they will smooth out an imbalanced wheel to within human tolerance. |
Sifo
| | Posted on Wednesday, June 23, 2010 - 03:38 pm: |
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The source of vibration damping is added mass and viscous fluid. The added mass reduces the natural frequency of the assembly and the visco-elastic connection of that mass to the assembly provides damping.
Note that all the demonstrations for these so-called balancing products always employ a HUGE imbalance. In reality, that is rarely if ever the case. In reality, the imbalance is mere ounces or portions of an ounce. In reality, the wheel/tire assembly doesn't vibrate very much at all.
What problem does that present for magic balancing beads?
Not enough impetus to move anywhere in the tire to achieve balance.
The beads provide damping in the same fashion as tuned mass dampers. Google it.
Yes we are very close to agreement, except for that damping thing. The beads being discussed neither use a fluid, or have enough mass to have any real damping effect. I did notice that the magnet they used to unbalance the wheel was huge! I also noticed that with the balancer it still wasn't as smooth as the balanced wheel. |
Blake
| | Posted on Wednesday, June 23, 2010 - 06:20 pm: |
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Mass damper...
The amount of mass to damp vibration corresponds to the magnitude of vibration input, in this case, the imbalance.
Stick a fence post into the ground. Whack it with a hammer. How far does it move? Whack it in rhythm to achieve maximum disturbance. How far does it move?
Now hold a similar hammer against the opposite side of the post that you hit. Whack the post as before both singly and in rhythm, the same rhythm but always returning the opposing hammer to back the impact of the whacking hammer. How far does it move?
There is no viscous fluid, just the reaction of unattached mass acting to damp the displacement reaction of the post.
Same may be true for loose beads inside a tire.
Fun discussion. |
Sifo
| | Posted on Wednesday, June 23, 2010 - 07:47 pm: |
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It sounds like you are talking about a damper to control harmonics. Difficult to say if that's what is going on in that video, but it certainly isn't the normal culprit associated with an out of balance wheel. Considering that we are talking about only adding a couple of ounces to a MC wheel I think you would only move the problem a few MPH one way or the other. Of course you wouldn't need all the movable beads or the fluid to accomplish that, only the mass.
Yes it has been a fun discussion... ARRRRRGGGGHHHH!!!!   |
Mako
| | Posted on Tuesday, November 01, 2011 - 02:07 pm: |
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have about 300 mi with dyna beads and they seem to work great. I am a little worried about the inside of the tire though. |
Reepicheep
| | Posted on Tuesday, November 01, 2011 - 04:19 pm: |
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I have about 1000 miles on my PR2's withOUT dynabeads (or any other balancing), and they seem to work great as well. And I'm not worried about the inside of my tire. Nor 8 ounces heaver. Nor $20 poorer.
Just saying...  |
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