Sports: Re: [DucatiST] Dyna Beads

The Yahoo!mail!server!does!horrid1things!to!my!formatting!so!I'm!trying!a!paragraph!without!'newlines'!today!

Thanks Aaron, that's interesting. I don't understand the physics, but I still have some doubts. The simulation in the YouTube video is unrealistic. There's no attempt to show what happens when the wheel is accelerating in the direction of vehicle travel or when the wheel is accelerated vertically by irregularities in the road. Also the demonstration uses a rigid tube, whereas beads inside a tyre are in an object that will be deformed by acceleration, and by rolling over irregularities. Of course, doing that on a moving test rig or real vehicle is difficult, you'd need a tyre with transparent side walls - surely impossible with cords - or cameras inside the tyre! Since the tyres we like use steel cords, radar wouldn't help. I suppose you could do high speed video with a powerful X-ray or gamma ray source! (Pass me the lead apron, Igor:) If I was a student, I'd turn this into a computer simulation project, however, I don't have the spare time and I guess that although I'd like to know the answer I'm not really too bothered by tiny weights on my wheel rims. 30 or 40 years ago, this might have been useful, but modern motorcycle tyres are made so precisely that I suspect I'd be happy with the ride even if they weren't balanced. Then again, thinking about it, I experienced horribly out of balance _wheels_ on cars 30 to 40 years ago, but never on motorcycles*. Perhaps it was more to do with those horrid pressed steel wheels on cars than the tyres, even then.

*My Velocette and Triumph would both cruise over 70mph, surely enough to reveal (wire) wheels out of balance?

--
Jan
On the road:'03 ST4s ABS (since April 2010), '99 M900 (since new)
Languishing: 'Guzzi V50 III & that legend of unreliability: a Lario!
Sorry, 'top posting' again, sigh.
Norwich, UK

Aaron Grossman, on Wed, Nov 23, 2011 at 09:42:00AM -0800 you wrote:
>
> further searching shows large bead examples with stroboscopic
> videography to show displacement
> http://www.youtube.com/v/skY6qvzpNXI
> i agree that the relative mass is great [the oz of dynabeads is roughly
> equal to the 30g weight that he strapped to it]
> if nothing else, it's a fun science project ;)
> funny enough, if you read the responses to any of these "proof" videos,
> one of the most common is "what's to stop me from using BBs/sand/etc?"
> the most common response is "possible clumping, lower density means
> more volume" which, to me, is marketing more than anything else.
> __________________________________________________________
>
> From: "ponsaerts.filip@telenet.be" <ponsaerts.filip@telenet.be>
> To: st2 owners <st2_owners@yahoogroups.com>
> Sent: Wednesday, November 23, 2011 10:51 AM
> Subject: Re: [DucatiST] Dyna Beads
>
> Hi Aaron,
> With respect to the video, I will not claim trickery either, but this
> video does not answer my question... ;) Sorry
> The video does not show the arrangement of beads while turning, which
> is the major item of their claim.
> But it does bring a cheap alternative to mind.... As the bottle gets
> heavier with the beads, I can do the same with any material I put into
> that bottle....
> So for all the users of dyna beads, why not start using some water, dry
> sand, or other cheap stuff in your tire which will evenly spread and
> resist the movement of the heavier part of your tire. ;)
> Sorry, I could not resist ;))
> Filip
> You do not need to drink seawater to know it is salty.
> ----- Originele e-mail -----
> Van: "Aaron Grossman" <agrossma07@yahoo.com>
> Aan: "st2 owners" <st2_owners@yahoogroups.com>
> Verzonden: Woensdag 23 november 2011 16:26:41 GMT +01:00 Amsterdam /
> Berlijn / Bern / Rome / Stockholm / Wenen
> Onderwerp: Re: [DucatiST] Dyna Beads
>
> I don't use dynabeads, haven't tried them, have no opinion either way.
> simply to answer the request for a video of how they work, perhaps with
> a clear cylinder, I googled "video dynabeads work" and found this as
> the first hit:
> http://www.youtube.com/watch?v=eq263AYgyYg
> I will not claim that there is no trickery here [as an engineer myself,
> I can see a number of ways that the veracity can be questioned] but it
> seems to at least answer your request.
> ~A
> __________________________________________________________
>
> From: "ponsaerts.filip@telenet.be" <ponsaerts.filip@telenet.be>
> To: st2 owners <st2_owners@yahoogroups.com>
> Sent: Wednesday, November 23, 2011 7:28 AM
> Subject: Re: [DucatiST] Dyna Beads
>
> Robert,
> A very nice slideshow, so a commercial from Dyna Beads.
> As an engineer, it does not tell me how it works. In fact, I think
> their story is faulty.
> If the beads distribute evenly on an unbalanced tire when it starts, I
> do not understand now why the beads would "resist" the "going up" of
> the heavy part of the tire.
> Having the beads going in a rotation, when no longer forced to go into
> rotation, the bead will tend go "outside" of the circle. So when the
> heavy part of the tire goes up, the bead will just follow.
> This is a direct consequence of the centripedal force....
> They also do not explain why the beads will distribute evenly on an
> unbalanced tire when it starts to rotate... To me this sounds like an
> assumption, but no evidence.
> Lastly, a tire is not "flat" on the inside. A lot of friction in there
> on the beads. so even if their story shows to be right, I think this
> friction will come in and disturb the process.
> They could have easily made a convincing video. Just take a plexy (see
> through plastic) cylinder, put in some beads, put one weight on the
> outside to unbalance, and have it rotate. Now that would convince me.
> Easy to do, isn't it. So why did they not do it..... right ;)
> Filip
> 01:00 Amsterdam / Berlijn / Bern / Rome / Stockholm / Wenen
> Onderwerp: Re: [DucatiST] Dyna Beads
>
> I don't use dynabeads, haven't tried them, have no opinion either way.
> simply to answer the request for a video of how they work, perhaps with
> a clear cylinder, I googled "video dynabeads work" and found this as
> the first hit:
> http://www.youtube.com/watch?v=eq263AYgyYg
> I will not claim that there is no trickery here [as an engineer myself,
> I can see a number of ways that the veracity can be questioned] but it
> seems to at least answer your request.
> ~A
> __________________________________________________________
>
> From: "ponsaerts.filip@telenet.be" <ponsaerts.filip@telenet.be>
> To: st2 owners <st2_owners@yahoogroups.com>
> Sent: Wednesday, November 23, 2011 7:28 AM
> Subject: Re: [DucatiST] Dyna Beads
>
> Robert,
> A very nice slideshow, so a commercial from Dyna Beads.
> As an engineer, it does not tell me how it works. In fact, I think
> their story is faulty.
> If the beads distribute evenly on an unbalanced tire when it starts, I
> do not understand now why the beads would "resist" the "going up" of
> the heavy part of the tire.
> Having the beads going in a rotation, when no longer forced to go into
> rotation, the bead will tend go "outside" of the circle. So when the
> heavy part of the tire goes up, the bead will just follow.
> This is a direct consequence of the centripedal force....
> They also do not explain why the beads will distribute evenly on an
> unbalanced tire when it starts to rotate... To me this sounds like an
> assumption, but no evidence.
> Lastly, a tire is not "flat" on the inside. A lot of friction in there
> on the beads. so even if their story shows to be right, I think this
> friction will come in and disturb the process.
> They could have easily made a convincing video. Just take a plexy (see
> through plastic) cylinder, put in some beads, put one weight on the
> outside to unbalance, and have it rotate. Now that would convince me.
> Easy to do, isn't it. So why did they not do it..... right ;)
> Filip
> Amsterdam / Berlijn / Bern / Rome / Stockholm / Wenen
> Onderwerp: Re: [DucatiST] Dyna Beads
>
> I don't use dynabeads, haven't tried them, have no opinion either way.
> simply to answer the request for a video of how they work, perhaps with
> a clear cylinder, I googled "video dynabeads work" and found this as
> the first hit:
> http://www.youtube.com/watch?v=eq263AYgyYg
> I will not claim that there is no trickery here [as an engineer myself,
> I can see a number of ways that the veracity can be questioned] but it
> seems to at least answer your request.
> ~A
> __________________________________________________________
>
> From: "ponsaerts.filip@telenet.be" <ponsaerts.filip@telenet.be>
> To: st2 owners <st2_owners@yahoogroups.com>
> Sent: Wednesday, November 23, 2011 7:28 AM
> Subject: Re: [DucatiST] Dyna Beads
>
> Robert,
> A very nice slideshow, so a commercial from Dyna Beads.
> As an engineer, it does not tell me how it works. In fact, I think
> their story is faulty.
> If the beads distribute evenly on an unbalanced tire when it starts, I
> do not understand now why the beads would "resist" the "going up" of
> the heavy part of the tire.
> Having the beads going in a rotation, when no longer forced to go into
> rotation, the bead will tend go "outside" of the circle. So when the
> heavy part of the tire goes up, the bead will just follow.
> This is a direct consequence of the centripedal force....
> They also do not explain why the beads will distribute evenly on an
> unbalanced tire when it starts to rotate... To me this sounds like an
> assumption, but no evidence.
> Lastly, a tire is not "flat" on the inside. A lot of friction in there
> on the beads. so even if their story shows to be right, I think this
> friction will come in and disturb the process.
> They could have easily made a convincing video. Just take a plexy (see
> through plastic) cylinder, put in some beads, put one weight on the
> outside to unbalance, and have it rotate. Now that would convince me.
> Easy to do, isn't it. So why did they not do it..... right ;)
> Filip