dynabeads... I'm gonna need more convincing.

[bjamesw]

Can anyone point me to any more authoritative analysis and demonstration on this sort of thing beyond the dude spinning BB's in a plastic water bottle on the end of a cordless drill on youtube?  Even that vidio is laughable.   At best he gets the bottle to balance only barely.  

Someone mentioned that this sort of thing is used on helicopter rotors.  I can't find that.  There are some cool animations online that show what is taking place, but I wonder if these are produced by the companies selling "dynabead" type stuff.

I decided to try something at least a little more accurate.  I took an eight inch diameter aluminum pot lid with enough curved lip at its outer diameter to contain a ring of BB's.   I drilled a centered hole and mounted it on my bench grinder.  To get a baseline I spun it up... 3400 rpm...  and there was only a tiny bit more vibration than without it mounted against the wheel.  So far so good.  Next I put about twenty BBs in the ring.   I spun it up.   The vibration was MUCH worse.  I slowed the grinder down sufficient to let the BBs spin independantly of the lid edge, and then started up again.  It's a very low hp grinder so the increase in speed is very gradual.    Same thing.   The imbalance was much worse than without BBs.  

These rpms are about twice what we'd be doing on motorcycle tires at about 80 (very roughly).  But the BBs against a smooth aluminum surface ought to provide a pretty good bench test.  Certainy the BBs were repositioning themselves somewhat or the vibrations would have been off the chart.  But as far as redistributing themselves sufficient to improve on the original dynamic balance of the empty pot lid... I was very disappointed.    

[Rob Valdez 79 R65]

I have NO idea what you are talking about.  I assume this is some "wheel/tire balancer"?
If so, forget it and get your wheel/tire balanced properly.
If you can't get it, remove the tire from the rim and see if the rim balances.
Is it a new tire that could be out of round?
Sometimes a new tube could have a heavy spot (I suppose).  Or the tube could be folded in the tire.

We really need more information than what you have given here.

[bjamesw]

Rob,   You've missed the debate on "dynabeads"?

Personally, I'm with you on this.  I'm quite far from trying this stuff out in the two wheels underneath me at 90mph.  But it's one of the
more interesting "snake oil" remedies out there.  (and why I put it here in the 'rants' section).

Google it.  Dynabeads.  There is a lot of discussion on it.  Of course you can dismiss it out of hand (I have too for the most part but it didn't stop me from trying a bench test with the idea), but if there really is anything scientifically, repeatably, and real world demonstrably to it, then it's worth taking a look at.  If you could get superior balancing for the life of a tire, more precise and constantly self adjusting to changes in tread wear, error (ice, mud, , stones in the tread, etc),  just by putting bead media in your tires, then it's worth talking about at least.

[Rob Valdez 79 R65]

Adding un-sprung weight when not necessary is never a good idea, IMO.

[nhmaf]

Dynabeads is the source of one of the longest, most heated threads on the BMWMOA forum, and I strongly discourage you from bringing it up there again or folks may get nasty to you.   I am a skeptic in most things, and this is one of the many things which I am unconvinced that they really do what people claim.  Additionally, many tire mfgrs will not honor a warranty replacement on a tire if it is found that these beads or other foreign material have been placed inside the tire.   I assume it may be the case for tube mfgrs too, but tubes probably don't have the warranty of the tire (nor do they cost as much).  In any case, I don't use them - though I have had some riders tell me that they are the best thing since sliced bread.

[montmil]

Snake oil. Nothing else. Right up there with the hydrogen fuel generator for your car.

Monte

[Rob Valdez 79 R65]

Snake oil. Nothing else. Right up there with the hydrogen fuel generator for your car.

Monte

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