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Push on or hang from spokes?

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Old 05-09-10 | 07:11 PM
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Originally Posted by Chris_F
This sounds more like a semantics problem than a structural engineering question.
ding ding ding.
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Old 05-09-10 | 07:55 PM
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Originally Posted by Chris_F
This sounds more like a semantics problem than a structural engineering question.
But semantics are important if you want to be understood. (Part of) The reason jargon exists is so that people can communicate clearly.
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Old 05-09-10 | 08:47 PM
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Originally Posted by Chris_F
This sounds more like a semantics problem than a structural engineering question.
yeah, I think I said that too earlier, but still here we are.
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Old 05-09-10 | 08:49 PM
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Originally Posted by wens
But semantics are important if you want to be understood. (Part of) The reason jargon exists is so that people can communicate clearly.
so much for that.
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Old 05-09-10 | 09:29 PM
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Originally Posted by ls01
so much for that.
If you went to the companies that design wheels and put their engineers together they would understand each other, fortunately wheels are not designed by internet experts. I would like to see the wheel the people who think a loss of tension is supporting a wheel would design though.
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Old 05-09-10 | 09:39 PM
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I think what drives the bike forward is a loss of tension in the bottom of the chain which allows the tension in the top to be released.
Also the pedals are driven around by the rider pulling up on them and not pushing.

Last edited by lazerzxr; 05-09-10 at 09:45 PM.
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Old 05-09-10 | 10:08 PM
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Originally Posted by lazerzxr
I think what drives the bike forward is a loss of tension in the bottom of the chain which allows the tension in the top to be released.
Also the pedals are driven around by the rider pulling up on them and not pushing.
The spokes pointing forward "push" the rim while the spokes pointing back "pull" the rim. It's amazing how so many of you just don't get it.... or I should say, refuse to get it.
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Old 05-09-10 | 10:53 PM
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Originally Posted by rydaddy
The spokes pointing forward "push" the rim while the spokes pointing back "pull" the rim. It's amazing how so many of you just don't get it.... or I should say, refuse to get it.
Funny thing is im not sure if your kidding or not having read some of the posts here
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Old 05-09-10 | 11:50 PM
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Originally Posted by lazerzxr
Funny thing is im not sure if your kidding or not having read some of the posts here
Funny, indeed. You should stick with what you're good at.
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Old 05-10-10 | 01:48 AM
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Originally Posted by rydaddy
Funny, indeed. You should stick with what you're good at.
WOW

Im actually not sure what you are trying argue anymore, I have forgotten. Just to put me straight on your way of thinking (which may very well be correct but I dont know what it is) Please explain the correct load path from grond to hub and explain what forces keep the hub central and the wheel stable when opposing spoke tensions differ.

Try to explain without using terminology like the hub either hangs or sits on the spokes so no one gets confused and rather than follow the load path from hub to ground, follow it the other way, so the ground pushes on the rim. Explain for a load large enough to release ALL of the tension in the bottom spokes plus a few N

I'm asking you because you may have a book that you can quote from which will use better and clearer language than I can be bothered to dream up. That way everyone will have the benefit of your knowledge which is the very reason people are on the forum.

The thing is I am agreeing with the analysis posted up because it is correct. I dont agree with some of the conclusions because it is easy to show they are incorrect. All you seem to be doing is laughing at people
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Old 05-10-10 | 03:28 AM
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Okay, fine. I'll enter the symantic fray. An unloaded wheel is already under a lot of complex internal stress. When a weight is applied the load in the spokes changes. Some increase in tension, some decrease. All of the spokes conspire together to support the load. None of them individually "carry" the load. The load doesn't "hang" from the top nor is it supported from below. It's supported by all of the spokes together. Take all of the spokes from one side out and the system fails.

Ditto the "which spokes drive" question.
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Old 05-10-10 | 04:36 AM
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Originally Posted by lazerzxr
I think what drives the bike forward is a loss of tension in the bottom of the chain which allows the tension in the top to be released.
Also the pedals are driven around by the rider pulling up on them and not pushing.
I was in a tug-of-war contest with my two daughters and when one of them let go, the other one pushed me right on to my ass with the rope. ;-)

(Darn. I was really trying to stay out of this...)
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Old 05-10-10 | 05:57 AM
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Next up, discussion on centrifugal force - real or imaginary**********??
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Old 05-10-10 | 07:09 AM
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it's a real pseudoforce...
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Old 05-10-10 | 08:50 AM
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Originally Posted by lazerzxr
WOW

Im actually not sure what you are trying argue anymore, I have forgotten. Just to put me straight on your way of thinking (which may very well be correct but I dont know what it is) Please explain the correct load path from grond to hub and explain what forces keep the hub central and the wheel stable when opposing spoke tensions differ.

Try to explain without using terminology like the hub either hangs or sits on the spokes so no one gets confused and rather than follow the load path from hub to ground, follow it the other way, so the ground pushes on the rim. Explain for a load large enough to release ALL of the tension in the bottom spokes plus a few N

I'm asking you because you may have a book that you can quote from which will use better and clearer language than I can be bothered to dream up. That way everyone will have the benefit of your knowledge which is the very reason people are on the forum.

The thing is I am agreeing with the analysis posted up because it is correct. I dont agree with some of the conclusions because it is easy to show they are incorrect. All you seem to be doing is laughing at people

My problem is I get pulled into these arguments and it's my own damn fault for not resisting the temptation. It comes up every few months and I just haven't smartened up enough to stay the F out of it. I get fired up pretty easily by comments that the hub "hangs" from the upper spokes (see ls01's post which I quoted earlier). It is a matter of semantics, but "hanging" is the worst of the two, the other being "standing" on the lower spokes. The bottom line is, the lower spokes lose much more tension than any of the other individual spokes gain, therefore, you tell me which ones are absorbing most of the load? Call it what you want, but it certainly does not prove to me that the hub "hangs" from above.

I don't claim that the other spokes are doing nothing. They're keeping the wheel together. I have read several wheel books and I don't think one of them claims that the hub "hangs" from the upper spokes. If you haven't read it already, Jobst Brandt's book is great for understanding all the mechanics of a wheel, especially for engineers, which I am one as well. That book was truly enlightening to me.

As for the "which spokes drive" question, well that's in the book too.
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Old 05-10-10 | 08:58 AM
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you are probably right, the hub is really pulling the top of the rim down.
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Old 05-10-10 | 09:01 AM
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^^^^^^^^^
And as far as which spokes drive the wheel forwardthats easy , the spokes in the front of the hub pull the hub forward and the tension in the trailing spokes pull the rim forward.
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Old 05-10-10 | 09:13 AM
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Originally Posted by ls01
^^^^^^^^^
And as far as which spokes drive the wheel forwardthats easy , the spokes in the front of the hub pull the hub forward and the tension in the trailing spokes pull the rim forward.
You couldn't be more wrong. What you describe is braking (only in reverse).
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Old 05-10-10 | 10:08 AM
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Originally Posted by lazerzxr
WOW (yada yada yada)
The only thing I caught from that was his poking fun at your grammatical error.
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Old 05-10-10 | 10:16 AM
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Check out the book the Bicycle Wheel by Jobst Brandt. It explains all this stuff and more importantly what to do with that knowledge. GL
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Old 05-10-10 | 10:53 AM
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Originally Posted by ls01
The ground does not push up on the wheel.


I disagree, Sir. Please see my Third Law.
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Old 05-10-10 | 06:38 PM
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Originally Posted by sirious94


I disagree, Sir. Please see my Third Law.
Why does it have something to do with having really big freekin' hair?

No, I get it but if I jump on the bike is the ground moving up at me? or am I moving down at the ground? The point was the ground is not supplying the load the bike is.
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Old 05-10-10 | 06:40 PM
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Originally Posted by kleinboogie
Check out the book the Bicycle Wheel by Jobst Brandt. It explains all this stuff and more importantly what to do with that knowledge. GL
I already build my own wheels, or should I consult with the engineers that designed the r sys wheels?
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Old 05-10-10 | 06:51 PM
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Originally Posted by rydaddy
My problem is I get pulled into these arguments and it's my own damn fault for not resisting the temptation. It comes up every few months and I just haven't smartened up enough to stay the F out of it. I get fired up pretty easily by comments that the hub "hangs" from the upper spokes (see ls01's post which I quoted earlier). It is a matter of semantics, but "hanging" is the worst of the two, the other being "standing" on the lower spokes. The bottom line is, the lower spokes lose much more tension than any of the other individual spokes gain, therefore, you tell me which ones are absorbing most of the load? Call it what you want, but it certainly does not prove to me that the hub "hangs" from above.

I don't claim that the other spokes are doing nothing. They're keeping the wheel together. I have read several wheel books and I don't think one of them claims that the hub "hangs" from the upper spokes. If you haven't read it already, Jobst Brandt's book is great for understanding all the mechanics of a wheel, especially for engineers, which I am one as well. That book was truly enlightening to me.

As for the "which spokes drive" question, well that's in the book too.
I agree, hanging and standing are pretty lousy descriptions. I tend to think of it more of being suspended, but the trap is when we start talking about position and direction then those terms spring into use.
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Old 05-10-10 | 07:16 PM
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Originally Posted by ls01
Why does it have something to do with having really big freekin' hair?

No, I get it but if I jump on the bike is the ground moving up at me? or am I moving down at the ground? The point was the ground is not supplying the load the bike is.
Technically both, unless the Earth became the immovable center of the universe recently.
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