DynaBeads

[cal_look_zero]

Has anyone else ever used these in your tires?

The idea is simple: Dynamic centrifugal balancing. Anyone who's ever ridden with an off balance wheel knows how much it sucks. DynaBeads are small ceramic beads that you put in your tire, that constantly shift and adjust for the best balance possible. As the wheel spins, the beads are pulled to the outside through centrifugal force, and balance the tire with every rotation.

I'm a skeptic by nature. Everything has a catch, nothing comes without small print, etc. I was "forced" into using these as a result of not having a means to balance my tires when I was on a road trip and swapped tires for a track day. Let me say that 140+ has never felt better on my bike.

Not only did they smooth out wheel buzz on my CBR, I also got a ridiculous amount of life out of my tires. Anyone with a modern sportbike rejoices when they can milk 4000 miles out of a set of grippy tires. I got 6200 out of my Bridgestone BT003rs tires, and only had to change after I got a puncture in my rear tire.

I like these things so much, I've gotten re-seller approval from Innovative Balancing (Company that makes DynaBeads) to try and get more people hooked on them. I'm going to post in the for sale section if anyone's interested.

[almarconi]

I've used them for years and for me they work. Do a search on this forum, some people like them and some don't.

[tkent02]

They work very well on all kinds of bikes. Those who don't agree don't understand the science and still think the world is flat, electricity is scary and if man was meant to fly God would have given him wings. OH, and the pictures from the moon were faked, too.

[81GS750]

I heard about these things a few years ago, but never tried them. I wonder if they work on trucks, with all the rough roads I drive they would be perfect! Generally I have to get tires rebalanced almost every 3000 miles due to lost wheel weights.

[cal_look_zero]

They don't work. First off, they are too light to do anything. Second, since the heaviest part of the wheel will attempt to scribe the largest arc, the beads will follow suit and further add to any imbalance. It's simple physics.

So you've used them at normal riding and extremely high track speeds, as well as tested the longevity of a set of tires with/without them?

Well then, what the heck have I had in my tires that's worked so well?!?!

I heard about these things a few years ago, but never tried them. I wonder if they work on trucks, with all the rough roads I drive they would be perfect! Generally I have to get tires rebalanced almost every 3000 miles due to lost wheel weights.

They do sell big packs for trucks, and they come highly recommended from RVers as well...

http://www.innovativebalancing.com/fleets.htm

[almarconi]

First off, they are too light to do anything.

On ounce of dynabeads weighs the same as an ounce of lead.

[1980GS1000E]

As the wheel spins, the beads are going to be propelled outwards via centrifugal force. If there is any one spot on the inside of the tire that is further away from the center (axle in this case), that is where the beads would end up. Given the modern tire manufacturing makes for are very uniform tire, I don't think there is such a spot, unless it's a really cheap, crappy tire. (On a side note, modern tires are so well made that when you change a tire, you can typically leave the wheel weights on and it'll be very well balanced as the wheels are more out of balance than the rubber). Now, if there is indeed an out of balance situation, the heavy spot on the tire is going to cause that spot to be pulled a little further away from the axle via the same centrifugal force and the beads will want to settle there thus increasing the out of balance situation. The physics of the system dictate that the beads should make the balance situation worse. On bigger vehicles, like trucks, the insanely huge mass of the tires is such that the beads have little noticable effect. I think that those who swear by them are suffering from the placebo effect. On a motorcycle, where the rotational mass is less and if the tires are perfectly (or very nearly so) round, my guess is that the beads distribute themselves pretty evenly as the tire gets up to speed and provide virtually no effect one way or the other.

[81GS750]

Good stuff, thanks for the link Cal.

[cal_look_zero]

As the wheel spins, the beads are going to be propelled outwards via centrifugal force. If there is any one spot on the inside of the tire that is further away from the center (axle in this case), that is where the beads would end up. Given the modern tire manufacturing makes for are very uniform tire, I don't think there is such a spot, unless it's a really cheap, crappy tire. (On a side note, modern tires are so well made that when you change a tire, you can typically leave the wheel weights on and it'll be very well balanced as the wheels are more out of balance than the rubber). Now, if there is indeed an out of balance situation, the heavy spot on the tire is going to cause that spot to be pulled a little further away from the axle via the same centrifugal force and the beads will want to settle there thus increasing the out of balance situation. The physics of the system dictate that the beads should make the balance situation worse. On bigger vehicles, like trucks, the insanely huge mass of the tires is such that the beads have little noticable effect. I think that those who swear by them are suffering from the placebo effect. On a motorcycle, where the rotational mass is less and if the tires are perfectly (or very nearly so) round, my guess is that the beads distribute themselves pretty evenly as the tire gets up to speed and provide virtually no effect one way or the other.

I can assure you that once you hit about 120, little imperfections in the balance start to amplify. I won't bore anyone with the math, but a modern 120/70/17 motorcycle tire will rotate approximately 2135 times per minute at 150mph; or 35.5 rotations per second. Now I don't know about you, but at those speeds, I'd prefer to not be fighting 35.5 unneeded vibrations per second.

Regardless of any "placebo" effect you might talk about in regards to vibe, there's no denying a huge leap in the longevity of the tire life. I've ran 2 sets of Bridgestone Battlax BT003r/s tires. 120/70/17 and 190/55/17. The first set got about 4300 miles before I was no longer comfortable on them; stick on wheel weights rebalanced every 1000 miles or so. The second set; in addition to 2 VERY aggressive trackdays, lasted 6200 miles; DynaBeads. Same general riding conditions (aside from track days): 90% slab commuter miles, 10% weekend warrior corner carving. So unless you want to argue that my trackdays resulted in nearly 1900 additional miles, I think I have pretty solid evidence.

[Dogma]

I still have some in the front of my 850. They work as advertised. They do have a significant effect, unless I got lucky and perfectly balanced a Cheng Shin Hi-Max on an aluminum cast wheel from 1980. The only problem I've ever had is that a large bump at highway speeds can upset the beads, which don't move around well at that speed. In other words, it shook for a little while, then smoothed out again. On reasonable surfaces, there's no problem, up to "track-like" speeds.

I did once read of a track bike whose tires got so hot that the beads embedded themselves into the tire and wouldn't move around anymore. I suspect that tire had bigger problems.

Think through the physics some more. Centrifugal force is not the only thing going on.

[cal_look_zero]

I still have some in the front of my 850. They work as advertised. They do have a significant effect, unless I got lucky and perfectly balanced a Cheng Shin Hi-Max on an aluminum cast wheel from 1980. The only problem I've ever had is that a large bump at highway speeds can upset the beads, which don't move around well at that speed. In other words, it shook for a little while, then smoothed out again. On reasonable surfaces, there's no problem, up to "track-like" speeds.

I did once read of a track bike whose tires got so hot that the beads embedded themselves into the tire and wouldn't move around anymore. I suspect that tire had bigger problems.

Think through the physics some more. Centrifugal force is not the only thing going on.

That's actually a really valid point I forgot to mention. These cannot be run in track slicks. Those tires are designed to get very hot and very supple. I've only ran in them in street tires on the track.

[salty_monk]

I've read of people using Airsoft BB's for a cheaper alternative in trucks, RV;s 4x4's etc...

Lots of info if you google. Never tried it myself.

[1980GS1000E]

DynaBeads website theory as to how they work would only apply if the tire wasn't trying to be forced around the geographical center of the wheel/tire assembly, i.e., the axle. By securing the wheel at it's center, you interfere with any self-balancing tendency. If DynaBeads worked, why haven't the tire companies and auto makers stepped on board? Wouldn't it be a lot easier for them at assembly to just throw some magic beads in the tire and not worry ever again?

[Dogma]

You're assuming the axle is held perfectly rigid, and it's nowhere near that. The compliance of the tire and suspension allow it to move up and down.

I think the reason OEMs haven't adopted DynaBeads is more economical than technical. The DynaBeads patent holders may want more royalties than the OEMs want to pay, the OEMs have a process in place and paid for that is probably very cheap to run, and switching to a different tire balancing method that people don't intuitively get will open them up to nuisance law suits. There just isn't enough economical up-side.

[1980GS1000E]

You're assuming the axle is held perfectly rigid, and it's nowhere near that. The compliance of the tire and suspension allow it to move up and down.

It is rigid enough to interfere with the principles of motion being discussed here, especially with regard to the rear wheel.