DynaBeads test

the reason this dynabead stuff started for me is my other bike is a 85 bmw k100rs, with one of those single sided swingarms
when you take the 4 lug nuts off theres a hole in the center big enough for a small bird to fly thru, takes a special tool that fits on a spin balancer and they have one at the bmw shop ($) and i don't go there unless it's payday and i worked some ot
after the weight trials i can see if you follow the paint dot to the heavy point on the rim, which ain't always the valve stem, there should be no reason to use anything but a static balance and the wheel bearings

 

Ok, I get it... BTW kudos for actually doing the test!

 

Yeah, and you'd have to glue them all to the side of the wheel opposite where the solder was placed.

 

If you go back to the "Fat front tire" thread someone actually looked up the physics behind this theory, and as reported the centrifugal force would in fact cause the beads to settle, or gather, at the point of imbalance.

 

No, you wouldn't. That's the point of dynamic balancing.

 

Maybe this will help. From the website:

That seems to make sense, Polock's Mythbuster test notwithstanding... :wink:

 

I have trouble with this statement I found on the dynabeads web site,,,,,can't put it on a tire balance machine to see if it works,,,,please profesors explain this,,,,an don't give me the it's to complicated to understand crap either,,,,sorry for the atitude to those that believe,,,,,but please give us some science, the industry standard machine can't balance the tire with these in it,,,,it does not say it takes awhile it says no!!!!

quote from dynabeads site
Can I put the tire on a balancer to see if it's working?
No. Dyna Beads operates on physics principles, and requires the tire assembly to be in motion against a road surface to detect the exact counterbalance position. An electronic balancer has a solid, fixed mount, and does not allow the tire to react to imbalance.

My vehicle has a [shimmy, shake, wobble]. Will your beads fix this?
No. There are three terms commonly used to describe lateral (back and forth) movement of the steering wheel, wobble, shimmy and shake. Two of these are a result of lateral imbalance of the tire/wheel assembly.

Wobble - this is more a function of mechanical suspension components than anything else, but can also be a result of bent or damaged rims.
Mechanical Imbalance - This is lateral movement caused from tire or wheel non-uniformity or improper bead seating. Corrected by measuring the amount of tire and wheel runout and replacing the defective component.
Weight-related Imbalance - This is lateral movement at normal driving speeds commonly characterized as "shimmy" or "shake" resulting from unequal weight on both sides of the tire and wheel circumferential centerline. The wider the tire, the lower the aspect ratio, the more likely this is to occur.

 

I like the fact that you are testing this, but the million dollar question is whether the weight of beads you add = the weight of the solder you have on the tire.

The weight of solder you add may have less of an effect when compared to the weight of the beads. What I mean is this: the wire was wrapped to the spoke of the wheel and has a difference in leverage (moment arm of inertia?) than the beads which are inside the tire and will settle on the surface. It is like spinning on your office chair with a 5 lb weight with arm extended vs the arm in towards the body. Same weight but different force due to the moment arm. Of course here we are talking an inch or two, but with a few grams, it may have an impact.

Just a thought, I may be off in left field here...

 

That's a lie. Just because they keep saying it won't make it come true.

 

That's because it works on faith! None of these kinds of scams can stand up to any kind of actual testing like checking the balance on a tire balancer.

 

You know, my tire is only round until it has the weight of the bike (and me) on it. Then it has a flattened spot at the road.........

I wonder what bumps do to the "Axis of rotation".

 

First off, a case of virtual beer and a hi - 5 to Polock for testing and reporting. Not that real men do alot of laundry, but have you seen a washing machine go out of balance? A pair of blue jeans gets wadded up on 1 side, and it pulls all the other clothes to the off-center mass.
Assume that the wash tub is perfectly round. The offset weight spins out-of-round, the axis of rotation is no longer the "axle", exacerbating the condition. All loose clothes goes to this new "low" spot.

On the other hand, semi trucks tires have had about 6 OZ of some white powder put in them for the balancer for a long time.

This powder, or the dyna-beads will bounce off the inside on EVERY revolution, at hiway speeds, as the tire flattens out at the bottom. The angle of the bounce would tend to move everything forward a bit.

On the XS link earlier in this thread, one guy commented that most people can't feel an imbalance until 3 1/2 OZ. Exactly where this experiment ended. I'd say more experimenting is in order.

Has anyone ever shaved a motorcycle tire true? I did a car set once.
Most tires have a slight hop to the tread. 1/4 inch + or - .

 

If you have faith the beads feel the centrifugal force in the rotating tire you've also got to have faith they will know what to do about the bump in the bottom! Faith based balancing won't work if you have doubts!

 

why not use a spin balancer to test the beads? because the wheel has to develop a shake for the center of mass to move from the center of rotation
so it has to shake before it can stop it from shaking, thats why beads can't be used on crank shafts, flywheels and such, they can't move, the bearings hold them
so on a bike wheel, really the only way it can move is inline with the forks or a arc with the swingarm, i guess the forks can flex to some extent but the swingarm can't stretch or compress, unlike a washer drum that can go anywhere
so now the little beads are looking for the low spot and equilibrium but it keeps changing, not to mention they keep getting bounced around by the contact patch
now comes the question, should i put the rest of them in the back tire ?
a little voice in my head keeps saying" if it ain't broke don't fix it"

 

Listen to the voice. It's never let me down. :wink:

 

Sure. Put them in. That's what they are for. You might be surprised to find that with the rest of them in there the tire will rotate in a completely balanced condition.

 

Which is exactly why it develops a wobble. The imbalanced wheel "tries" to balance itself around its center of mass (the point at which mass is equally distributed around). However, it can't since it's tied to a fixed point (the axle). So the tire tries to pull the axle to it's center of mass which in turn pulls the forks or swingarm. Then the motion moves to the bike frame or handlebars which can be felt as a wobble, shimmy, or shake as the bike absorbs the energy being passed to it from the imbalanced wheel.

Also a washer drum is fixed as well, just not as much as a wheel is. If you've ever see a washer that's incredily out of balance walk across the floor, then you've seen then drum forcing the washer to spin about it's center of mass rather than the "axle".

 

Are we getting any closer to a bottom line on the Dyna Beads?

Do they ... or, ... don't they work as advertised?

I thought the science behind it proved they would balance the tire out?
I don't see any debunking of them on the web!

 

I knew I should have run my tires without them first, just to see if there was any difference.

But since they're in, screw taking them out.

And no matter what Steve says, I honestly believe they work.

 

What I want to know is why would anyone spend money on faith based beads that won't work to balance the tires unless you believe in them when you can REALLY BALANCE the tires for free by just re-using the existing weights or turning the tire so it balances without any weights?