Topic: Ever heard of dynabeads?

[BVCB650]

Definition

A placebo effect occurs when a treatment or medication with no therapeutic value (a placebo) is administered to a patient and the patient's symptoms improve. The patient believes and expects that the treatment is going to work, therefore it does.

The placebo effect is also a factor to some degree in clinically effective therapies, and explains why patients respond better than others to treatment despite similar symptoms and illnesses.



Thank you Answers.com

Didn't work for me. Beads shook the crap of my bike. Had to go to the dentist to replace fillings.

[Retro Rocket]

Excellent posts Mlinder, good to see we are back on track...

Mick

[mlinder]

I think I've got it figured out.
I think it may work to a certain degree.
I've run it by both the engineer and the physics (minor ), and will see what they say before I post it.

[BVCB650]

Yes yes, but do they have faith?

[mlinder]

Yes yes, but do they have faith?

Depends on what you are talking about

[BVCB650]

That sir, is the million dollar question. Faith in the force, faith in the things that go bump in the night, faith that Oswald acted alone etc.

[SiliconDoc]

" Incidentally, that's the reason I think SiliconDoc's belief the beads will fly about inside the tube when the contact patch shifts them up is crap. Wait! Actually, this is pretty easy! Since the radius of curvature of the tire as it transitions to the contact patch will always be less than the radius of curvature of the wheel, and since there's a constant tangent rate (road speed), the acceleration due to contact patch will always be less than the acceleration due to wheel rotation. Therefore, the beads will never lift off of the surface of the inner tube due to the contact patch."

INCORRECT. First of all, I said the beads would lift off the inner bottom of the tire on a bump, but a similar action occurs at the contact patch. What you're failing to notice, while the radius length of the circular travel of the beads is reduced at the contact patch, the beads speed is also reduced - constant travel speed is REDUCED, as the tire compresses. The tire diameter is less at the contact patch, the beads have moved closer to the hub very quickly.
 As the tire approached BDC, the rubber is compressed - this is part of what causes heating of the tire, amongst other things ( & lateral forces applied through the sidewalls etc.). The speed of the beads is REDUCED. No constant rate.

So while you're busy declaring I am wrong for some false group satisfaction, you've forgotten a very basic fact. The bike has weight, and the tire compresses at road contact - the tangent rate of the beads is reduced, their distance from the hub is reduced, they are heated as they undergo compression like the tire at ground...

I can't help it if you all agree to be wrong together. It certainly is not my fault.
cont.' later after you admit your error... I'll bet that takes forever.
  

[mlinder]

" Incidentally, that's the reason I think SiliconDoc's belief the beads will fly about inside the tube when the contact patch shifts them up is crap. Wait! Actually, this is pretty easy! Since the radius of curvature of the tire as it transitions to the contact patch will always be less than the radius of curvature of the wheel, and since there's a constant tangent rate (road speed), the acceleration due to contact patch will always be less than the acceleration due to wheel rotation. Therefore, the beads will never lift off of the surface of the inner tube due to the contact patch."

INCORRECT. First of all, I said the beads would lift off the inner bottom of the tire on a bump, but a similar action occurs at the contact patch. What you're failing to notice, is the radius length of the circular travel of the beads is reduced at the contact patch. The tire diameter is less at the contact patch, the beads have moved closer to the hub very quickly.
 As the tire approached BDC, the rubber is compressed - this is part of what causes heating of the tire, amongst other things ( & lateral forces applied through the sidewalls etc.).

So while you're busy declaring I am wrong for some false group satisfaction, you've forgotten a very basic fact. The bike has weight, and the tire compresses at road contact - the tangent rate of the beads is reduced, their distance from the hub is reduced, they are heated as they undergo compression like the tire at ground...

I can't help it if you all agree to be wrong together. It certainly is not my fault.
cont.' later after you admit your error... I'll bet that takes forever.
  

See my post a couple up.

Doesn't change the fact that you are freakin' bonkers. (and that most of the reasons you state for these working are pretty whacky, even if you are correct about them working.)

(I'll also add that even if they do work, and as I said, I think I figured out why they might, at least to a degree, I'll never use them. IF they work, they work under a very small set of parameters, and those parameters are not often part of the conditions under which I ride.)

[coldright]

I figured that he would have to come home from work at some point.  Everyone got a front row seat and some popcorn?  Let the show begin.  

*I'd love to stay and watch, but I have some overhead insulation and electrical work that needs to be done.  Can't decide which is more fun, this or that.*

[Clutch Cargo]

I have Dynabeads in my front and rear tires on my 750K6.   They distribute after 100 yards of riding - then your fine. 

Good for around town driving - I would not put them on a tourer.

BTW - yes with tube tires - you have to make a very small funnel

Clutch

[dilbone]

" Incidentally, that's the reason I think SiliconDoc's belief the beads will fly about inside the tube when the contact patch shifts them up is crap. Wait! Actually, this is pretty easy! Since the radius of curvature of the tire as it transitions to the contact patch will always be less than the radius of curvature of the wheel, and since there's a constant tangent rate (road speed), the acceleration due to contact patch will always be less than the acceleration due to wheel rotation. Therefore, the beads will never lift off of the surface of the inner tube due to the contact patch."

INCORRECT. First of all, I said the beads would lift off the inner bottom of the tire on a bump, but a similar action occurs at the contact patch. What you're failing to notice, while the radius length of the circular travel of the beads is reduced at the contact patch, the beads speed is also reduced - constant travel speed is REDUCED, as the tire compresses. The tire diameter is less at the contact patch, the beads have moved closer to the hub very quickly.
 As the tire approached BDC, the rubber is compressed - this is part of what causes heating of the tire, amongst other things ( & lateral forces applied through the sidewalls etc.). The speed of the beads is REDUCED. No constant rate.

So while you're busy declaring I am wrong for some false group satisfaction, you've forgotten a very basic fact. The bike has weight, and the tire compresses at road contact - the tangent rate of the beads is reduced, their distance from the hub is reduced, they are heated as they undergo compression like the tire at ground...

I can't help it if you all agree to be wrong together. It certainly is not my fault.
cont.' later after you admit your error... I'll bet that takes forever.
  

but can you quantify the effect of such a "contact patch?"

Also, the faster the wheel travels the smaller the contact patch...

If these beads are experiencing anywhere from 100-300 g's of centripetal acceleration as a result of their circular motion do you really think that the "contact patch" is going to reduce that force enough for them to randomly begin flying around the inside of the tube.

Let's assume for a moment that the beads at the contact patch lose contact with the tube(or other beads...whatever they may be in contact with)they are still wanting to continue on in a straight line tangent to the circular path.  Where will they find themselves?  right back on the tube... I doubt the amount of motion induced by the contact patch is going to have a legitimate effect on the beads.

As I stated earlier... I think these may work under certain conditions...but there are other larger issues at hand than a "contact patch"

The problem with this is that none of us have much to go on in terms of quantifying all of this.  We can make up some numbers sure...but is that "real"...or just our best attempt at what "real" is?

[paulages]

Mark- an analogy for what I believe bistromath is trying to say: imagine that you're on one of those space camp G-force rides (I grew up near huntsville, AL where NASA has their space camp museum  ), where it spins and spins until you're plastered to your chair. Now imagine overcoming that force to crawl around to wherever you imagine the analogous "heavy point" to be. The force keeping you from travelling radially past your chair is stronger than the force attempting to get you to that farthest point from the axis.

I think that's what he's saying anyway.

Yes, he did say that, but that's only true if acceleration is instantaneous from a standstill to whatever the speed may be that I can no longer move from my chair.

Hi Paul

I was attempting to provide a scenario where you could imagine yourself in the position of the beads, if you will. Let's make it simpler: you're on a merry-go-round, spinning fast. if you've ever done this you know that it's difficult to move around the merry-go-round once it gets spinning.

You make a good point though... there would need to be some force allowing for equal distribution for the beads to not simply clump at the point in which the radial force overcomes gravity. For that matter though, what would cause them to overcome this centripital force and find the furthest point,?

[Retro Rocket]

what would cause them to overcome this centripital force and find the furthest point,?

Good point, also i was wondering, because of the "G" forces that these very hard little beads are experiencing and the speed they travel at, what would be happening to the inside of the tyre when these things "jump" after hitting the contact patch where the tyre flattens out on the road, wouldn't this have a kind of "sandblasting" effect on the inside of the tyre??

Mick

[mlinder]

The problem with this is that none of us have much to go on in terms of quantifying all of this.  We can make up some numbers sure...but is that "real"...or just our best attempt at what "real" is?

I think this is doable. The problem is that there are so many variables. degree of imbalance, weight of wheels, and suspension being in there. I think it's quantifiable, though.

[BobbyR]

[Qingdao]

I just don't see what is so hard about adding weights and balencing wheels...Are we that lazy?!?

[Achmed]

Part of my issue with this discussion is me not really knowing the reason wheel assemblies are unbalanced. I assume it could come from a number of factors, like:

variation in center of mass of hub
variation in rim weight along circumference
spoke length differences (not very likely?)
actual out-of-roundness of outside diameter of tire
variation in thickness of tire tread and wall
variation in profile of tire
then there's the tube and valve

It seems like which of the factors contribute most to the imbalance would affect the method used to determine where the beads would end up. I'm just thinking out loud here.

[1974CB750rider]

I cannot believe this #$%* is still going. Its gotten to the point of being silly as hell.

[w1sa]

My short take on this subject is that the beads are most affected by friction/drag and gravity.

An out of balance rotating wheel will experience a change in centre of mass and move towards that centre if not contained. The changing centre of mass alters the friction/drag (co-efficient?) experienced by the beads against the wall of the wheel. The beads will move towards the highest friction/drag area which contains them in a momentary state of balance. This will occur at points furthest from the centre of mass and the spread of the beads is most likely relative to the wheels movement/velocity away from a balanced position where the centre of mass is equal to the radial centre of the wheel.
As the wheel's centre of mass moves back toward the wheel's radial centre, the beads will move/spread to maintain balance and Vice versa.

Apart from practical engineering and safety concerns it would seem that the beads should have a greater ability to maintain rotational balance across a wider speed range.

The limitations affecting the use of fixed lead weights at the outer rim to maintain balance are no less important at higher speeds.

Cheers...........................Geof

[Gordon]

I cannot believe this #$%* is still going. Its gotten to the point of being silly as hell.

It was silly a few days ago.  Now it's just stupid. 

[Frankenkit]

"Must I say it?"

"You must! You must!"

"It's like our very own 'Three Physicists, One Cup (of beads)'

everyone tries to look away, and yet... there it is...

[mlinder]

The experts are still out on my hypothesis....

[Retro Rocket]

My short take on this subject is that the beads are most affected by friction/drag and gravity.

An out of balance rotating wheel will experience a change in centre of mass and move towards that centre if not contained. The changing centre of mass alters the friction/drag (co-efficient?) experienced by the beads against the wall of the wheel. The beads will move towards the highest friction/drag area which contains them in a momentary state of balance. This will occur at points furthest from the centre of mass and the spread of the beads is most likely relative to the wheels movement/velocity away from a balanced position where the centre of mass is equal to the radial centre of the wheel.
As the wheel's centre of mass moves back toward the wheel's radial centre, the beads will move/spread to maintain balance and Vice versa.

Apart from practical engineering and safety concerns it would seem that the beads should have a greater ability to maintain rotational balance across a wider speed range.

The limitations affecting the use of fixed lead weights at the outer rim to maintain balance are no less important at higher speeds.

Cheers...........................Geof

There is no problem with lead balancing weights for motorsport but the company that makes these beads says well read for yourself.
http://www.innovativebalancing.com/LowProfileTires.pdf


Mick

[1974CB750rider]

I wished it would quit raining outside so I could go ride my bike with my kickass dyna bead balanced tires. It rides so smooth.

[BVCB650]

The thing is, and this really the only thing left to say, when is someone going to balance a wheel........ road it, then take the weights off and put in beads for comparison? Others have done it and I have posted their positive feedback.