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Mayor of Simpleton
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Has anyone used Dynabeads? on the track? Do you use more or less, by weight, than standard lead weights? Even with an engineering background, I'm having a tough time figuring out how they work. I would think they would just settle into the "low areas" where the diameter is greatest. I guess with enough of them, they would form a strip all the way around the center, but that seems like it would be heavier than the traditional remedy and a have nothing to do with filling the light spot. I'm thinking it's just akin to turning the tire into a flywheel and masking the imbalance instead of curing it. Anyone care to shed some light?
 

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I just put them in my bike because I've heard so many positive reports but won't actually try them until later this week when my bike is finished.
We (ECS and I) put 2-OZ of them in the rear and 1-OZ of them in the front as recommended.

What I also hear is you don't want to use them with "track rubber" due to the softer compound sticking to beads.

Here are other threads for you:
http://www.ducati.ms/forums/56-superbikes/124612-dyna-beads.html

http://www.ducati.ms/forums/56-superbikes/123814-1198-high-vibrations-high-speeds.html

Here's their explanation:
http://www.innovativebalancing.com/HowItWorks.htm
 

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I don't buy their explanation. Makes no sense to me (maybe also because of my engineering background :D). The centripetal force which acts on the beads is basically just the mass of the beads multiplied by the angular acceleration, which is caused my the motion of the tire. This motion, and therefore the centripetal force acting on the beads has nothing to do with the deformity or unbalanced rubber in the tire. Then again you can't really check that because you can't see the beads, but if you could see them somehow I'd be curious what would happen if you just tape something to the side of the tire. That would throw off the balance significantly and IF you could see the position of the beads while the tire is spinning, you could check to see if anything changed.
 

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I posted this on another forum

I would use Dyna beads on a cruiser, but not on a sport bike that's going to be driven hard. The beads will balance a tire that's going at a constant speed, but track use they can't work, it's against the law.

Newton's First Law " A body in motion remains in motion unless it is acted on by an external force. If the body is at rest it remains at rest."

So when the tire accelerates the beads have to catch up to the tire speed, when you brake the beads have to slow down. Seeing as when you are on the track the tire speed is constantly speeding up and slowing down, the tire will never balance. Dyna beads where designed for tractor trailers where the acceleration is slow, and the speeds are constant.

Just my opinion:think:
 

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I have had them in the wheels of my Tuono . Have not had good luck with them. The balance is there at a constant speed, not when decel or accel, and is quite disturbing at times. Have had a front end hop that simply would not go away while in a corner. I have since went to traditional weights. They may work as intended for slower rotating tires but I think that since sportbike tires change speeds so quickly the beads simply cant keep up with those changes. That is my take on them.
 

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Mayor of Simpleton
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Discussion Starter #8
Yeah, I was skeptical from the beginning and now there's no way I'll run them.
 

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Bon Vivant
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I had them in my FJR, the damn things would go out of balance and stay there if I accelerated a bit too hard from a stop. I had to actually pull over and stop to reset them. They gave me so much trouble I had to go to a bike shop and have them removed while on a five day tour.

I'll never use them again. good 'ol weights work great for me.
 

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Nine16 et al – As an Aerospace Engineer I’ve kicked this around the office a bit and I’ll attempt to explain the “magic” of dynabeads as they are a very real solution based on a principle widely used in balancing washing machines and commercial trucking to name a few. Like most people, my first instinct is to assume that centripetal force (force that pushes an object rotating around an axis away from the axis – the force that throws a child off a merry-go-round) will simply make the beads roll to the part of the inside of the tire that’s the furthest from the axle. Our instinct would be absolutely right if the axle was positively fixed to something rigid (and the reason why you can never try to balance a wheel with dynabeads on a conventional balancer). Fortunately for us, the axle is attached to flexible suspension. What REALLY happens with an out of balance wheel is that it has a new center of mass that’s in a different location than the axle. The suspension flexes and allows the unbalanced wheel to rotate about it’s TRUE center of mass. This is the wobble and vibration you feel with an out of balance tire. Because the center of mass is closer to the heaviest part of the wheel, the opposite side is actually further away from the virtual axle (center of mass) and so the beads are compelled again by centripetal force to go there, which concentrates mass opposite the heavy spot and balances the wheel. The suspension allowing the wheel to rotate about its true center of mass is the part that most people (including me) don’t envision first. Think about spinning a hammer in the air – it doesn’t rotate in the center of the handle, it rotates near the head while the lighter side of the handle swings madly around at a higher speed. Now, what if the handle was hollow and half filled with dynabeads? Yup, they’d migrate straight over to the handle side opposite of the head – in effect counteracting the heavy side and making the hammer spin around its geometrical center. The other miracle of physics is that all this shifting happens in a fraction of a second and can adapt extremely quickly to changing conditions in balance – for example if you bend your rim on a pothole you might not even notice it. The downside to this technology is of course fix-a-flat makes an absolute mess by clumping the beads. And yes, I’ve put dynabeads in one of my motorcycles (2003 BMW F650GS – worked great!). Hope this helps.
Quick addition - things that can make dynabeads less effective are; too many or to few beads, an out-of-round (not concentric) tire or wheel, any moisture in the inside that can impede your beads, disintegrating beads made of inappropriate corrosive materials...
Oh yeah - for reasons mentioned by others above, probably not a great idea for the track due to strong accel / decel.
 
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