Topic: Dyna beads evaluation

[scottly]

The only conclusion I come to is agreeing with BobbyR  about being concerned these little beads wearing on my inner tube.  I think they had them in the Hula Hoops when we were kids.  They made that wooshing sound.  Might be cool if they did it on your bike.

Shoop-shoop hula hoop...

[Roach Carver]

Okay, now im interested. Wheres the link to the naked girl with the beads.

[BeSeeingYou]

Did you notice in the product video that they seemed to need to spin up to speed before they balanced srust58?

If the video doesn't have nude or at least semi nude chicks in it I can't be bothered to watch.  My gut feeling (for what that's worth)   is that a small imbalance is not critical at slow speed.

LOL +1 on the video's but some how i think we have very different roads. 

While it's a given that they need a certain RPM to kick in it has been my experience that a tire imbalance is noticeable above 30mph thus my comment about it not being critical at slow speed.

[CoachDoc]

I've seen a few guys now express concern about scuffing or wearing the inside of their tires if Dyna Beads are used. On this I can shed some light, having just recycled the beads in the Dunlops on my Goldwing after 18K miles. I sucked them out with tubing taped to a dustbuster with the bag removed. The material I sucked up had a negligible amount of black dust, presumably from the tire lining, mixed with the beads. The inside of the tire was pretty unremarkable in look and feel. I did notice the beads seemed a little glazed or oily- maybe from compressor oil or distillates in the rubber. I washed them off in acetone and now they're in the new Dunlops.

These things are very hard, very round, and seem very smoothe. Overall, I'm thinking concern about tire abrasion is not warranted.

[CoachDoc]

While it's a given that they need a certain RPM to kick in it has been my experience that a tire imbalance is noticeable above 30mph thus my comment about it not being critical at slow speed.
[/quote]

Agreed. Plus at speed the rotational forces are so strong I don't believe the beads will deviate significantly once balance has been achieved.

[BeSeeingYou]

I've seen a few guys now express concern about scuffing or wearing the inside of their tires if Dyna Beads are used. On this I can shed some light, having just recycled the beads in the Dunlops on my Goldwing. I sucked them out with tubing taped to a dustbuster with the bag removed. The material I sucked up had a negligible amount of black dust, presumably from the tire lining, mixed with the beads. The inside of the tire was pretty unremarkable in look and feel. I did notice the beads seemed a little glazed or oily- maybe from compressor oil or distillates in the rubber. I washed them off in acetone and now they're in the new Dunlops.

These things are very hard, very round, and seem very smoothe. Overall, I'm thinking concern about tire abrasion is not warranted.

Gee, a first hand report from some one who has used them.  Who woulda thunk it.

[Retro Rocket]

Here's an interesting read for anyone that cares....

Balance
First, let's first discuss theoretically what we are trying to do with dynamic balance. A dynamic imbalance is where the center of gravity (Cg) isn't around the center of rotation. This is the very similar to what we think of static balance, but the imbalance only shows up when you rotate the wheel/tire. Consider the wheel/tire on your bike, when it's sitting still, there is no dynamic imbalance. There can be a static imbalance and you can fix that pretty easily; we already do this when we manufacture a device. However, if you start spinning that wheel, there will be a dynamic imbalance if the Cg isn't right on the axial. Consider that the tire is sitting on the ground...it has a deflection which means it's mass isn't uniformly distributed anymore. That implies things like the quality of the tires, the lot, air pressure, the road surface, and even your weight all affect the dynamic balance. It should be obvious that a great many things can affect the Cg of your spinning wheel/tire and that's exactly why static balancing can't fix a dynamic imbalance.

An interesting side point is those tire balancing machines. You might ask how we can dynamically balance tires with what amounts to a static weight. We can't, at least not for all RPMs. Basically we cheat and purposefully create a slight static imbalance so as to reduce the dynamic imbalance. The dynamic imbalance is constantly changing though so static weights can only solve the problem at a given RPM. If you spin the wheel slower or faster it will become dynamically imbalanced again. Those balancing machines aren't really finding a single point solution, they are attempting to find the best compromise.

This should be even more obvious with the Hunter RoadForce machines (best commercially available AFAIK). They apply a substantial force on a roller to the tire so that it acts like the tire is rolling along the ground. A tire balanced that way is practically guaranteed to be statically imbalanced! However, it actually creates a better balanced tire because the sidewall stiffness of the tire varies (as does the rim concentricity). E.g. a high spot on the rim (which doesn't have to show up in a static balance!) on a hard part of the sidewall will give a bad ride as the resulting system isn't concentric. The point isn't to get a tire which will spin well on an unloaded axial or has good static balance, it's to get one that is properly dynamically balanced under load. You want the effective Cg to be right on the axial when in use, who cares about a test bed. As a quick side note, when using a tire balancer like the RoadForce you can actually line up the stiff part of the sidewall with a rim depression or vice versa. This usually isn't need if you have good quality rims and tires. Remember, you will never get perfect balance...engineering is the study compromises, so you can get of close enough for practical purposes.

One last thing on balance. All of this isn't to say that static balancing isn't of value. On the contrary, it's very important too, but just not for the reason most people assume. Most people are trying to achieve a dynamic balance with a static solution. As we talked about, you can't do it. However, consider this. Let's say you spend a lot of time statically balancing your rims and checking their concentricity (got to do both!). A rim is a fairly rigid system and as such, if you just spin it up there should be very little to no dynamic imbalance. Think about it. The statically balanced rim has it's Cg over the axial, unless there is a mass shift, which a rigid system like the rim really doesn't have much of, there won't be a dynamic imbalance either. The Cg doesn't magically change because you start spinning it; it changes when mass moves around in the rotating system. Of course the problem is that as the rim gets dirty or you mount something which isn't as rigid (e.g. a tire) or you put it under load (e.g. ride on it since that deflects things like the tire and even the rim a tiny amount) you've just created a dynamic imbalance. Thus, it should be apparent what a good static balance does for you...it gives you a good starting point for a mostly rigid system that doesn't experience too much mass deflection to achieve dynamic balance. That's great because it's easy to do and because it should significantly reduce the amount of dynamic balancing mass you need. As we'll discuss soon, those moving masses which allow for a dynamic balance aren't free of bad side effects; thus minimizing them with a good static balance helps.

Don't forget about concentricity either! You can have a statically and dynamically balanced system which isn't symmetric/concentric. I.e. a perfectly balanced rim which isn't concentric is going to have a very bad ride.

Autobalancers
So to fix this situation we need to figure out a way to move some mass around the rotating system so as to bring the rotating Cg back to the axial and that's what autobalancers do (and active balancers, but that's a different thread). Simply put, they exploit the physics of a rotating system so as to "perfectly" redistribute the mass and achieve dynamic balance. This is how Olsson 2004 describes it:
Another alternative is a mechanism that automatically adjust the balancing state, referred to as autobalancing. The are primarily two applications for this alternative: (1) when extreme accuracy is necessary (disk drives may be an example), and (2) when the state of balance is continuously or intermittently changed. A typical example of this is the centrifuge for a laundry machine, however fans, grinding wheels, and separators also belong to this category.
Sounds great, right? It is, but all isn't rosy.

There are several different theoretical ways to build an autobalancer. The most common is two rings/races each with a ball bearing that can freely move in them (a lubricant is often used as a dampener too).

Such dynamic imbalance has inspired the use of self-compensating, automatic dynamic balancing (ADB) mechanisms for eccentric rotors. The principal idea behind the ADB is that the balancing balls are subjected to a driving force caused by an apparent centripetal force acting from the offset centre of mass to each ball. When the speed of rotation is below the first resonance, this driving force pushes the balls towards the imbalance, thus moving the centre of mass away from the centre of rotation. However, when the speed of rotation is greater than the first resonance, the driving force pushes the balls to the opposite side of the rotor than the imbalance, thus moving the centre of mass towards the centre of rotation. Viscous damping in the ball race causes energy dissipation, allowing the balls to come to rest in asymptotically stable steady-state positions.

Let's look at some of the requirements or operating modes of the system to understand when it works well and when it doesn't. Olsson 2004 discusses the basic theory, Horvath/Flowers/Fausz 2005 discusses the theoretical, analytical, and experimental two pendulum balancer and has some good practical application, and finally Green/Champenys/Friswell/Munoz 2011 discusses the possibility of more than two balancing masses. I'll only use the first name/date from here on out.

At least two balls/rings...
You can also build this with two rotating pendulums. One ball/pendulum works too, but unless the mass of the balancer is exactly equal to the mass of the imbalance it will create its own imbalance. You must use at least two to achieve a perfect dynamic balance.
Thus far the rotor has been regarded as a point mass. All real rotors also have an extension and, consequently, a moment of inertia. This also means that they have two or more natural frequencies and dynamic as well as static unbalance. In order to balance such rotors one must have two balancing planes and in order for the auto-balancing to work there must be two balancing rings... It is obvious that a perfect balancing requires two balancing rings. If only one exists, perhaps for some practical reasons, there will be a residual unbalance.

Simple enough, Dynabeads has many balls so they shouldn't have a problem here unless it impossible/impractical for all of those balls to completely counterbalance each other out. More on that later.

"Free" balls
This article deals with the method of free balls. The basic theory includes any number of balls, but is valid only if the balls stay out of contact with each other...
This implies that for a two ball system you must have two independent rings/races for the balls to move in. I think this is because if the balls come into contact with each other they can degrade to a single ball solution under certain parameters and as we already discussed, you need at least two. Of course that means they are offset a bit and that should cause a torque around the z axis (the suspension forks). The masses should be small so it should be much though.

Dynabeads has many balls, but they are not independent of each other. Thus, under certain conditions they could degrade into a single "ball" solution. However, I don't think that is the case. The Dynabeads are small enough and are "captured" by the tire in such a way that I think they partially behave like a liquid would. I.e. the apparent centripetal force is sufficient that it will "flatten" them out and not allow a sufficient clumping like two balls in the same ring. That however brings up the next point.

Fluids as an Autobalancer
Nearly everyone cites Thearle 1932 in their papers, but only Green 2011 makes this note:
In this paper, there is also a discussion on why an ADB consisting of a fluid, in place of solid weights, would not work.
ADB is Automatic Dynamic Balancer. I do not have a copy of Thearle 1932 so I'm left only my rationale. I think the reason for this is because the apparent centripetal force is so great that unless the ADB mass can hold itself together, like a solid weight would, it gets somewhat uniformly distributed ("flattened") around the container (in our case the tire) and don't act as a true counter balance. Thus, solid masses can behave very much like a point mass solution, the liquid can't.

Dynabeads are small enough that I think they also behave partially like a liquid and partially like a solid mass solution. The liquid properties are good because it should allow them to avoid the two or more dependent masses degrading to a single mass solution (see Free Balls above), but that comes at the expense of the somewhat uniform distribution of the beads (aka liquid like), which results in most of them not acting as an autobalancer. A detailed analysis of these mechanisms should be possible, but I'm generally satisfied that the beads are a reasonable compromise at steady-state. They partially behave like an autobalancer, but require much more mass to achieve the required redistribution of the Cg than a solid mass solution would. That additional mass, above and beyond what an ideal/true autobalancer requires, has all the problems of adding un-sprung/rotational mass to your motorcycle.

I suspect that the size/material of the beads was a compromise between these two properties (or it should have been). This also implies that the liquid in tires as an autobalancer is nonsense.

Concentricity
Dynabeads takes it on the chin here...
Again we note that the ring will rotate with its center stationary, and the rest of the rotor has to adjust its motion to this. This confirms the result as obtained for the eccentric ring: the only way for the balls to be at rest is when the ring is running concentrically. This means that there is no guarantee that the rotor as a whole will run smoother, even if the balancing in itself has been successful... Deviations from a perfect ring geometry will greatly aggravate the possibility to balance. In particular, an ellipticity can cause severe residual unbalance.
Ouch. Since the tire is the dynabeads "ring" it can't be concentric...the fact is that the tire is loaded and thus deflected and not round (remember it's one reason why we have the whole dynamic balance problem in the first place). Even if the balancing sort of works, it can't become stable as the ring is eccentric! Thus, we have a perpetually unstable system, which while it may provide some level of autobalancing, it will never come close to an optimal autobalancer.
I would guess this tendency is exacerbated by bikes like cruisers which use a bias ply tire and less so by those that use a radial. The bias ply should exhibit more non-concentricity as it conforms/flattens to the road more than a radial does. I'd bet this is why wide tires are an issue more so than narrow.

Autobalancer Mass
Since at least two solid masses are required for the autobalancer to work properly, each mass should be approximately half of the total dynamic mass imbalance. Any more mass than that and you amplify the negative stability problems (which we haven't covered yet) and get even more of the usual issues with adding more rotational/un-sprung mass. If the two masses are very close to the dynamic imbalance they will take a position approximately 180 degrees from it. If they are too little they will be exactly at 180 degrees, but won't move the Cg enough to totally cancel the dynamic imbalance. If they are more than is needed they will separate and take a position between 90 and 180 degrees from the imbalance. If they are less than 90 degrees from the dynamic imbalance they will be unstable and the whole system will suffer. If this isn't quite clear take a look at Horvath 2005 as they have some good pictures you can use to increase your understanding.

The problem is this, how much dynamic imbalance do you have? I certainly don't know and its going to vary widely from bike to bike, wheel to wheel, and tire to tire. Don't forget that you actually have to add more mass than the ideal autobalancer would because some of the Dynabead mass will behave like a fluid. This is probably the biggest practical issues of implementing a Dynabead solution. I'm sure through testing you could come up with some rules of thumb, but IMHO it's a hack at best.

Supercriticality
Basically a real rotor has at least two natural frequencies and until you spin the rotor fast enough the physics involved with an autobalancer actually make the vibrations (whirl) worse, not better. In an ideal autobalancer where the balancer mass is equal to the imbalance it will be twice as bad as the autobalancer mass will "align" with the imbalance. Now that's just the rough sketch of it as in reality it won't perfectly align since the system is highly unstable in this region (if you are accelerating to get to supercritical rotation). All you need to understand is that until you spin it fast enough (aka supercritical), a system with an autobalancer will be unstable and will amplify the dynamic imbalance, not make it better.
For subcritical operating speeds, the steady-state phase delay of the displacement related to the exciting force is less than 90O. In this case, the stable pendulum position will be between 0O and 90O as measured from the horizontal axis (as shown in figure 11.a) which exacerbates the mass imbalance of the system.

Dynabeads has the same problem although the fluid mechanism of it may actually help a bit on a steady-state sub-critical rotation as a portion of its bead mass won't act like an autobalancer. However, its worse when you consider the non-stead-state system...Dynabeads should behave worse than an ideal autobalancer.
This could explain why many GS riders think it makes their bike worse, they probably ride sub-critical and Dynabeads do make it worse.

Stability and Perturbations
This is, IMHO, the absolute worst thing for Dynabeads and all autobalancers on a motorcycle. I think this is exactly why your BMW doesn't come with autobalancers from the factory. It's not that they couldn't, it's really that we probably shouldn't. Factor in that Dynabeads is a sub-optimal autobalancer in many ways which exacerbates all of the issues with autobalancers (except a minor one which I noted above) and I'm convinced not to use them. Again, YMMV.

Simply put, autobalancers have bad transition states when not in steady-state and everything you do on a motorcycle, besides cruising at a constant highway speed, perturbs them considerably. The faster you go, the less susceptible an ideal autobalancer becomes and the longer it takes to settle back to steady-state. Worse still is that based on the above analysis I don't think Dynabeads can achieve state-state stability.
Only recently have fully nonlinear analyses of the autobalancer been undertaken. Based on a Lagrangian description of the equations of motion, steady-state bifurcation studies were carried out by Chung & Ro (1999) and by Adolfsson (2001), who identified regions in parameter space where stable rotating states, whether balanced or not, are possible. By moving to a rotating frame, Green et al. (2006a) carried out a detailed nonlinear investigation in the case of two balls, by computing both isolated branches of periodic solutions and those emanating from Hopf bifurcations of the equilibrium states. Significant regions of bistability were found between these steady and periodic states, chaotic states and states in which the balls rotate at a different angular frequency than the rotor. Furthermore, perturbations were shown to result in a large growth in the vibration before subsequent transient decay. This prompted the study by Green et al. (2006b), where the authors used the concept of pseudospectra to analyse this sensitivity to perturbation. It was found there that while the completely balanced state becomes increasingly stable for high rotation frequencies, it also becomes increasingly sensitive to perturbation, with an increasingly larger transient response before settling to the steady state.

This explains why the sport bike guys generally hate them, they are constantly perturbing the system and experiencing it's very negative effects. At high speeds the transient becomes very severe. Accelerate, turn or brake and the portion of the Dynabead mass that's acting as an autobalancer is working against you. That's not my opinion, that's a know. Exactly how and how bad depends on a lot of factors.

[FuZZie]

Thanks CoachDoc, could you give a idea of the miles involved?

Reto Rocket could we have a link to your source? Sounds like the poster knows his stuff but I'd still like to check that and for bias. Thanks very good read!

[Spanner 1]

Wow, that's quite a read !.....
Word of the day has got to be ; 'pseudospectra '.......

[CoachDoc]

Thanks CoachDoc, could you give a idea of the miles involved?

18K on the GL1500's Dunlops when the beads were recycled. Previously I never had a front tire last more than 12,000 before severe cupping necessitated replacement.

[Retro Rocket]

Thanks CoachDoc, could you give a idea of the miles involved?

Reto Rocket could we have a link to your source? Sounds like the poster knows his stuff but I'd still like to check that and for bias. Thanks very good read!

http://rsta.royalsocietypublishing.org/content/366/1866/705.full.pdf
http://downloads.hindawi.com/journals/ijrm/2004/783480.pdf
http://74.220.207.117/~horvathl/PASSIVE%20BALANCING%20FOR%20ROTOR%20SYSTEMS%20USIN G%20PENDULUM%20BALANCERS.doc

[FuZZie]

Much thanks guys! 

[FuZZie]

Mommieeeeeee..... my brain hurts! 

Joking aside, the site truncated your third link Retro Rocket  "auto shortening urls" suck, but i don't need it.
I started off thinking it would work but in some mediocre fashion (example like only at certain speeds) but the absolute worst place you could use this tec is in a motor cycle tire!   

[MCRider]

They are advertising in the MSTA (Motorcycle Sport Touring Association) newsletter. members are well heeled with high priced top of the line late model equipment. I'll be interest in listening to their remarks. I suspect they will be similar to this thread.    Pro and Con.

That's not an endorsement. I'm sure we wouldn't turn down a paid advertisement unless it was an outright safety issue.

[Retro Rocket]

I did a lot of reading last night and on another site a mechanic chimed in a said that in his experiences he would never use them at all, he said that they don't balance the wheel, they try to counteract the vibration if there indeed is a problem in the first place. He also said that on the balancer that he used {computerized} the balance of the wheel with beads was never consistent, showing different results each time it was put on the balancer.... He also said that they are absolutely useless for racing or anyone that is hard on brakes and likes to push their bikes. All the comments to the positive were anecdotal and not based on anything else. What surprises me is that if they worked as well as the manufacturer says then why don't they have any scientific info on the site to back up their claims.? Just advertising blurb.... Anyway, just thought i would post that up as i found it very interesting.....If you think they work then go ahead and use them, i certainly won't be.....

[Retro Rocket]

They are advertising in the MSTA (Motorcycle Sport Touring Association) newsletter. members are well heeled with high priced top of the line late model equipment. I'll be interest in listening to their remarks. I suspect they will be similar to this thread.    Pro and Con.

That's not an endorsement. I'm sure we wouldn't turn down a paid advertisement unless it was an outright safety issue.

Thats interesting Ron, on one of the sites that the guys ride big multi purpose bikes, there is a general dislike for the beads in those type of bikes, instability, vibrations and other quirky behavior was noted.....I probably should have posted that link as well but i read for about 2.5 hours and didn't bookmark everything... If i come across the site again i will post the thread....

[FuZZie]

They are advertising in the MSTA (Motorcycle Sport Touring Association) newsletter. members are well heeled with high priced top of the line late model equipment. I'll be interest in listening to their remarks. I suspect they will be similar to this thread.    Pro and Con.

That's not an endorsement. I'm sure we wouldn't turn down a paid advertisement unless it was an outright safety issue.

That would be strategic, it would get it's best performance by:
Driving on a smooth road, with gentle cornering, brand new rims and a bike decked out with cruise control! 

[MCRider]

They are advertising in the MSTA (Motorcycle Sport Touring Association) newsletter. members are well heeled with high priced top of the line late model equipment. I'll be interest in listening to their remarks. I suspect they will be similar to this thread.    Pro and Con.

That's not an endorsement. I'm sure we wouldn't turn down a paid advertisement unless it was an outright safety issue.

That would be strategic, it would get it's best performance by:
Driving on a smooth road, with gentle cornering, brand new rims and a bike decked out with cruise control! 

The majority of members in the MSTA have nothing to do with "gentle cornering" and cruise controls. The emphasis is on Sport, not Touring.    Many also ride the big high fender adventure bikes, but even on the pavement only bikes, road condition is not an issue.

They flat fly. The very best of our SOHCs is a piker compared to the average modern sport touring bike. 150mph with saddlebags and fairing.

Dynabeads is taking a chance advertising there. But as mentioned, I think its the type of product that will still get the pros and cons discussion of a thread like this. With no conclusion.  People are people.

I won't use them as i just don't see the point. I've had at least 10 tires on my FJR and never an issue with a plain old tape weight or clip weights balance. No one's ever said to me Ron get those ugly weights off that bike.

[Retro Rocket]

I also tried to find someone that sold them in Australia with no luck at all, they are virtually unheard of in Europe as well.....
Funny thing is , i have never ever had a tyre that was out of balance enough to even "feel" any difference whilst riding, if i had have, i would be looking at why,  first by checking bearings, tyre fitment, swingarm bushes first, then i would look carefully at the tyre to see if there are any deformities or poor fitting.....

[FuZZie]

They are advertising in the MSTA (Motorcycle Sport Touring Association) newsletter. members are well heeled with high priced top of the line late model equipment. I'll be interest in listening to their remarks. I suspect they will be similar to this thread.    Pro and Con.

That's not an endorsement. I'm sure we wouldn't turn down a paid advertisement unless it was an outright safety issue.

That would be strategic, it would get it's best performance by:
Driving on a smooth road, with gentle cornering, brand new rims and a bike decked out with cruise control! 

The majority of members in the MSTA have nothing to do with "gentle cornering" and cruise controls. The emphasis is on Sport, not Touring.    Many also ride the big high fender adventure bikes, but even on the pavement only bikes, road condition is not an issue.

They flat fly. The very best of our SOHCs is a piker compared to the average modern sport touring bike. 150mph with saddlebags and fairing.

Dynabeads is taking a chance advertising there. But as mentioned, I think its the type of product that will still get the pros and cons discussion of a thread like this. With no conclusion.  People are people.

I won't use them as i just don't see the point. I've had at least 10 tires on my FJR and never an issue with a plain old tape weight or clip weights balance. No one's ever said to me Ron get those ugly weights off that bike.

I was just being cynical and goofing a bit.

[MCRider]

They are advertising in the MSTA (Motorcycle Sport Touring Association) newsletter. members are well heeled with high priced top of the line late model equipment. I'll be interest in listening to their remarks. I suspect they will be similar to this thread.    Pro and Con.

That's not an endorsement. I'm sure we wouldn't turn down a paid advertisement unless it was an outright safety issue.

That would be strategic, it would get it's best performance by:
Driving on a smooth road, with gentle cornering, brand new rims and a bike decked out with cruise control! 

The majority of members in the MSTA have nothing to do with "gentle cornering" and cruise controls. The emphasis is on Sport, not Touring.    Many also ride the big high fender adventure bikes, but even on the pavement only bikes, road condition is not an issue.

They flat fly. The very best of our SOHCs is a piker compared to the average modern sport touring bike. 150mph with saddlebags and fairing.

Dynabeads is taking a chance advertising there. But as mentioned, I think its the type of product that will still get the pros and cons discussion of a thread like this. With no conclusion.  People are people.

I won't use them as i just don't see the point. I've had at least 10 tires on my FJR and never an issue with a plain old tape weight or clip weights balance. No one's ever said to me Ron get those ugly weights off that bike.

I was just being cynical and goofing a bit.

Thanks. Apologies if my reply seemed touchy.   

[FuZZie]

No worries 

[CoachDoc]

I just searched the MSTA website for a DynaBead thread. First thing that comes up is a page with users who used them and found that they liked them, followed by people who never used them posting their criticism. Basically, this thread in another context. The late not so great Howard Cossel was once famously quoted as saying "opinions are like ass%$#@s- everybody has one". I think this thread fairly well bears this out.

http://www.sporttouring.us/showthread.php/7426-Dynabeads

[FuZZie]

I just searched the MSTA website for a DynaBead thread. First thing that comes up is a page with users who used them and found that they liked them, followed by people who never used them posting their criticism. Basically, this thread in another context. The late not so great Howard Cossel was once famously quoted as saying "opinions are like ass%$#@s- everybody has one". I think this thread fairly well bears this out.

http://www.sporttouring.us/showthread.php/7426-Dynabeads

That's not true what about landon?

    I have used them and still not sold on them. The problem I have is that more than once I have mounted tires and just put them on the bike with no balancing at all. I have ridden those sets and never could tell a tire was out of balance. Most companies do not even mark their tires any longer because they claim they at that close to perfect. So my question is how do you really know if the beads are working or if the tire is just ok without weights? Unless some mounted a tire and road it for a couple hundred miles and had a bad vibration because the tire was out of balance and then installed the beads and it corrected it, then I might believe they work. I don't think I will spend much more money on them.

    Landon
    2005 Honda ST1300

and what about this bit?

I had trouble balacing my front tire on the FJR...at least two tires would hop slightly above 80 mph. With 3 installs of beads I get no more hop, even at more elevated testing. This alone is proof for me.

so did he install them 3 times to fix the rim or use 3 packs to get stable at 80?

I mean no offence, but i'd try reading those papers on the physics instead just following others. I didn't bother to read anything after that last quote I'm sorry but I rapidly lost trust in the source.

[Retro Rocket]

I read piles of threads last night with about a 50/50 for an against and all the guys that were for the beads had nothing to back up their claims apart from "perceived" improvement , so it goes both ways, And like i stated earlier, i have NEVER had an out of balance tyre that i could feel on any bike i ever owned, and every bike has been ridden hard, well over 100 MPH. Did you read the post i made earlier?, There is a lot of science and explanations in the post and links posted .....   I find it quite weird that all of a sudden there is all these guys with out of balance front tyre's, was this the case before Dyna beads, i would say not.....