spoke tension for Mavic CXP 10?



alfeng

Well-Known Member
Jul 23, 2005
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ScienceIsCool said:
Alfeng, if you have an argument to make and wish to counter the prevailing wisdom, you would do well to elucidate. As it is, I think you've confused two terms. Lateral stiffness and strength.

The lateral stiffness of any wheel is defined by the following elements:

- beam stiffness of the unsupported rim between spokes (second moment of inertia)
- bending stiffness of each spoke (related directly to the second moment of inertia). For a round spoke, this is dependent on diameter. For aero spokes it's a bit more complicated.
- number of spokes.
- to a very tiny degree, wheel stiffness is affected by the number of spoke crossings. Empirically, the lateral stiffness is measured to go down with the number of spoke crossings. I.e., radial wheel is laterally stiffer than a 3x

So it could very well be that the straight guage spoked wheel is laterally stiffer than a double butted spoked wheel. Then again, it might not. There's a few variables to consider.

I would define the strength of a wheel is it's ability to handle riding conditions without breaking. Swaging a spoke (double butting) allows you to put more material is high stress zones such as the elbow and threads. It also allows you to take material away from the central portion where it is not needed. I could see how this would indeed make a stronger wheel.

Lastly, the experts are often recognized as such for a reason. It's important to question any claim (it's a great way to learn and discover), but to stand in a public forum and say they are wrong... I'd suggest that you have a very clear argument why that would be the case.

John Swanson
www.bikephysics.com
Well, I thought I did "elucidate" my argument -- gyroscope ... in-/stability ... that is, if you are trying to turn the wheel and the lateral instability of the softer spokes of a double butted lacing allows the wheel to momentarily continue in a given direction from where the rider is directing the bike.

I am basing MY observation on first-hand experience. Empirical evidence with noodly lacing which was NOT noticeable when moving in a straight line ... granted, an extreme. Reproducable if one is daring or foolish.

Anecdotal, but number crunching by me would certainly NOT satisfy you ... so, why should I bother?

CONSIDER THIS:

Skiers, for example, know that a stiffer ski is easier to control.

A stiffer ski boot is also a benefit to control.

Yet, a soft ski is easier to control at bunny hill speeds by a novice or inexperienced skier who doesn't know how to set his/her edges ... so, that is what they use. They just don't know better, and the speeds at which they are traveling are not handicapped by the soft skis.

If that doesn't make sense then I have to say that if you can't think out of the conventional wisdom box which you have apparently trapped yourself inside of and "work with me" on this ... then, I can't expand upon this further because I won't be able to convince you ... and, as I have said before, it doesn't matter to me whether someone incorrectly chooses to think that a double butted lacing is better ...

As I said, I used double butted spokes in a wheel I laced for myself this past Spring ... but, I know the potential limitations ... I know how the wheel is going to be used.

John, you're the one into doing the math ... MY contrary-to-the-conventional-wisdom shouldn't be the basis for your investigation ... your curiosity should be enough motivation.

ONE MORE TIME, for a beach cruiser or townie then a double butted lacing is the BEST ... but, those are the bikes that won't have that lacing due to the premium one has to pay for the double butted spokes.

So, I say the emporer has no clothes. That's just the way I see it. If you can't see it, then I can understand why you wouldn't want to crunch the numbers.

Let the TRUE BELIEVERS continue to worship their sacred cow and say I am a heretic ... its the way of the world.
 

alfeng

Well-Known Member
Jul 23, 2005
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Retro Grouch said:
If you push down on a stack of coil springs, the weakest ones will always flex first. Your bike rides on pneumatic tires. They probably flex 10 times as much as everything else put together. I think that it's all-too-easy to overstate the effect of relatively tiny differences in other, much stiffer, components.
Geez. How little air is in your tires? How slowly are you riding?
 

Retro Grouch

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Dec 29, 2005
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alfeng said:
Geez. How little air is in your tires? How slowly are you riding?[/QUOTE

Man! You go on and on and on about how stiffer is better but offer not one single iota of evidence to show that your straight gauge spokes are stiffer.
It's starting to get boreing. Give me something that I can think about.
 

Retro Grouch

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ScienceIsCool said:
- bending stiffness of each spoke (related directly to the second moment of inertia). For a round spoke, this is dependent on diameter.
What about tension on the spoke? It seems to me that a spoke is relatively easy to bend in space but, when built into a tension wheel it's much harder to bend. I suppose that a thinner spoke would elongate more and consequently bend more easily but wouldn't other factors, like the rim flexing inward, be more instrumental?
 

alfeng

Well-Known Member
Jul 23, 2005
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Retro Grouch said:
alfeng said:
Geez. How little air is in your tires? How slowly are you riding?[/QUOTE

Man! You go on and on and on about how stiffer is better but offer not one single iota of evidence to show that your straight gauge spokes are stiffer.
It's starting to get boreing. Give me something that I can think about.
Talk about incessant!

I'm sorry that my failure to reply to your almost ridiculous remark about your underinflated & squishy tires while responding to someone else's more sincere query has filled your silly little head with things you don't want to think about.

People/Everyone in this forum can disagree with me regarding which type of spoke to use. I honestly don't care since I use both; but, I know the limitations of a wheel built with double butted spokes and am willing to live with that "limitation" under some circumstances.

I simply began by stating the Park Tensiometer reading for a straight 14 gauge spoke -- the end user can/could look at his/her spec sheet to extrapolate an acceptable tension for the particular spoke type being used.

If one person says that he thinks that double butted spokes are better ... well, fine.

FWIW. I use a Wheelsmith Tensiometer whose readings are, unfortunately, propietary for the specific tensiometer, so THAT is why I was simply stating the numerical value for the OP's Park Tensiometer. Does 23.5 fall outside the range spec'd by MAVIC for their rims? I don't think so.

BTW. You are the one prolonging the discussion by parroting remarks which you clearly don't have a clue about. You are out of your element regardless of how many wheels you may-or-may-not have built.

BTW2. When did Schraner write the first edition of his book on wheel building? This is a REAL question which anyone can reply to. Is Schraner still alive? Again, a real question ...
 

ScienceIsCool

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Jun 25, 2006
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alfeng said:
Geez. How little air is in your tires? How slowly are you riding?
Well... The modulus for metals is around 100,000 Mpa and the tire pressure is at ~1 Mpa. So, unless your frame elements (tubes) are tiny the tire will deform by several orders of magnitude more than anything else on your bike.

And consider me done with this thread. Alfeng, your arguments are not coherent to me and you seem to be combative. This means that we can't really debate the science involved in a rational way. Yup. You'll flame me for saying that, but I will not be responding.

I believe that double butted spokes can make a stiff and strong wheel and can back it up with references. I do not follow your arguments about gyroscopic forces leading to flexible wheels. I do not know how that relates to double butted spokes.

John Swanson
www.bikephysics.com
 

ScienceIsCool

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Jun 25, 2006
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Retro Grouch said:
What about tension on the spoke? It seems to me that a spoke is relatively easy to bend in space but, when built into a tension wheel it's much harder to bend. I suppose that a thinner spoke would elongate more and consequently bend more easily but wouldn't other factors, like the rim flexing inward, be more instrumental?
I agree that it's not intuitive, but I've read several experimental studies that show lateral stiffness is nearly unaffected by spoke tension. Unless the spokes are nearly completely slack.

The modulus (stiffness, or stress/strain) of a material is pretty much a constant unless the material is close to the elastic deformation limit and beyond. So I guess it does make sense. It's just not intuitive.

John Swanson
www.bikephysics.com
 

alfeng

Well-Known Member
Jul 23, 2005
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ScienceIsCool said:
Well... The modulus for metals is around 100,000 Mpa and the tire pressure is at ~1 Mpa. So, unless your frame elements (tubes) are tiny the tire will deform by several orders of magnitude more than anything else on your bike.

And consider me done with this thread. Alfeng, your arguments are not coherent to me and you seem to be combative. This means that we can't really debate the science involved in a rational way. Yup. You'll flame me for saying that, but I will not be responding.

I believe that double butted spokes can make a stiff and strong wheel and can back it up with references. I do not follow your arguments about gyroscopic forces leading to flexible wheels. I do not know how that relates to double butted spokes.

John Swanson
www.bikephysics.com
Have I been combative with you?!?

You asked me to "elucidate." I thought I did.

Others made remarks to which I replied in kind.

I don't believe that I ever said that a wheel laced with double butted spokes couldn't make a stiff and strong wheel ... I just would never recommend it because, IMO (obviously, ONLY in my opinion in this forum!), it won't be as good as a wheel laced with a straight gauge spoke ...

BTW. If you think about it, the tires are almost irrelevant to the gyroscopic forces EXCEPT that they add weight near the circumference ... and presumably, contribute to the inertia.

If you (that's a generic-you, as in "anyone") can't envision how the gyroscopic forces MAY-or-may-not come into play, then there would be little reason for you to investigate further. No problem on my part.

ONE MORE TIME SINCE THIS STATEMENT IS FALLING ON DEAF EARS:


I have wheels which I have laced with double butted spokes. I just laced a set FOR MYSELF last Spring -- however, I don't think they are better AND I don't think the final wheel is better OR stronger than a wheel laced with a single gauge spoke.


I will note that if Schraner wrote his tome circa 1980 AND if he is the basis for this urban myth, that I can reasonably speculate why he made the statement. If Schraner's pronouncements were made within the last dozen years, then his reasoning makes no more sense to me than mine APPARENTLY do to you!


You know, the conventional wisdom amongst some people IS/WAS that the Pope was infallible. So, because that is still the conventional wisdom amongst some people, are you saying that I should believe THAT conventional wisdom?

I'm glad you are questioning ME. You should if ANYTHING I post doesn't ring true ...

But, so too, perhaps you should not be afraid to question the conventional wisdom.

Early 60s conventional wisdom. Eggs & Butter are bad for you.

21st C conventional wisdom. Eggs & Butter are NOT bad for you.

In a recent thread in this forum, someone questions the conventional wisdom that aluminum frames are (sorry this isn't verbatim) uncomfortable to ride!

... His observation is one with which I don't have a problem ... but, if I were to believe the conventional wisdom, I would question his observation and that of others who echo his sentiment.

So, please don't parrot something you've read someplace if you haven't actually investigated the situation.

If you want to discount my empirical observations & conclusion(s), then make your own empirical observations rather than speculating ... record the data. Repeat the experiment -- you know, that's supposedly what science is about.

Remember, it is said that Bumblebees theoretically shouldn't be able to fly ... so, theoretical speculation has limitations.
 

Retro Grouch

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ScienceIsCool said:
The modulus (stiffness, or stress/strain) of a material is pretty much a constant unless the material is close to the elastic deformation limit and beyond. John Swanson
www.bikephysics.com
So John, What's the tensile strength of a stainless steel spoke with a 1.5mm center section? I've kind of assumed that it had tensile strength to burn but that lack of torsional strength would make skinnier spokes too hard to build with. Would I be right if I said that during normal use it would still be a long way from that "elastic deformation limit"?
 

fish156

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Mar 26, 2005
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alfeng said:
I will note that if Schraner wrote his tome circa 1980 AND if he is the basis for this urban myth, that I can reasonably speculate why he made the statement. If Schraner's pronouncements were made within the last dozen years, then his reasoning makes no more sense to me than mine APPARENTLY do to you!
.
Speaking of speculation/s, this one is way off target - as most of your speculations are. Schraner's book was published in 1999, complete with at least one picture of him taken in 1998. So, there's a pretty good chance that he still alive, as if that makes any difference.

It's pretty clear that you don't have a copy of Schraner's book, yet you feel free to disregard some of the major statements in it. And this book was written by a man who spent most of his working life specializing in wheelbuilding. If you want people to accept your opinions then maybe it would be a good idea to back up your own statements with the published - and accepted - statements of others. So far, you have done nothing but expect the members of this forum to accept your unsubstantiated opinions and offered nothing else of substance. You seem to love obscure and irrelevant references, so here's a couple for you. Cold fusion and successful human cloning were both claimed to be accomplished by scientists. But, as most people know, those claims turned out to be faked when the authors were put to task. They could not back up their claims with repeatability or second sources. You, also, seem to have neither for your opinions.

The recurring theme in this discussion is that everyone keeps asking you for substance and you have none to offer. People are not going to buy what you say just because you say it. If you can't back up your statements with something other than your own opinion, then your credibility is pretty near zero, no matter how many obscure and irrelevant references you make and no matter how many different fonts you use.

You got a couple of replies from members that were willing to have an open discussion about this subject and you wasted no time in insulting them. This seems to be your modus operandi with anyone that disagrees with you. It's just a little narrow minded to think that you're the only one who could be right.
 

alfeng

Well-Known Member
Jul 23, 2005
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fish156 said:
Speaking of speculation/s, this one is way off target - as most of your speculations are. Schraner's book was published in 1999, complete with at least one picture of him taken in 1998. So, there's a pretty good chance that he still alive, as if that makes any difference.

It's pretty clear that you don't have a copy of Schraner's book, yet you feel free to disregard some of the major statements in it. And this book was written by a man who spent most of his working life specializing in wheelbuilding. If you want people to accept your opinions then maybe it would be a good idea to back up your own statements with the published - and accepted - statements of others. So far, you have done nothing but expect the members of this forum to accept your unsubstantiated opinions and offered nothing else of substance. You seem to love obscure and irrelevant references, so here's a couple for you. Cold fusion and successful human cloning were both claimed to be accomplished by scientists. But, as most people know, those claims turned out to be faked when the authors were put to task. They could not back up their claims with repeatability or second sources. You, also, seem to have neither for your opinions.

The recurring theme in this discussion is that everyone keeps asking you for substance and you have none to offer. People are not going to buy what you say just because you say it. If you can't back up your statements with something other than your own opinion, then your credibility is pretty near zero, no matter how many obscure and irrelevant references you make and no matter how many different fonts you use.

You got a couple of replies from members that were willing to have an open discussion about this subject and you wasted no time in insulting them. This seems to be your modus operandi with anyone that disagrees with you. It's just a little narrow minded to think that you're the only one who could be right.
You are kidding, right?

What? Because I refuse to bow at the feet of the god of double butted spokes I am recalcitrant?

I don't see how my failure to embrace what people parrot is an unwillingness to discuss the matter ...

I was asked me to elucidate.

I thought I did.

You clearly have chosen NOT to comprehend what I have said while reading into my statements things I am not saying.

If you don't understand the principle of how a gyroscope works and how it applies to my conclusion, then I have failed to clarify.

Further, I have described an EASY test anyone can do to see how a rim deflects -- simply grab some spokes and notice how the rim is NOT rigid ... oh, gee, I didn't phrase it THAT way, now did I?

Regarding ScienceIsCool's earlier statement with regard to the modulus of elasticity (okay, he just said "modulus"), you ignore the logical conclusion from his abbreviated statement!

That is, if there is X-amount of material, and the cross section of a double butted spokes is 3/4 the cross section of a single gauge spoke (you CAN do the math, can't you?), then doesn't it necessarily follow that the wheel laced with double butted spokes will be more flexible ... if tensioned to comparable spec.

Think about it.

AND, based on what you and others are espousing, motorcycle spoked wheels should be able to use 14-15-14 double butted spokes ... but, they don't. HMMM, I wonder why ...

I have repeatedly stated that I don't expect to convince anyone that straight gauge spokes might be better since it is clearly considered to be an heretical statement.

Where's anyone's proof other than suggesting that so-called experts have said so?

Regarding Schraner, et al. Why would I waste my money-or-time as you have to read misinformation? 1999? Shameful ... as noted, if he wrote his book in 1980 the I would allow him an "out" for originating an urban myth ... since I know Brandt's work predates 1999, is he the originator?

What? Is your idea of "substance" a series of formulas?

Here ... to over-simplify it for you ... compare 32*.75 & 32*1.0.

If the resulting numbers represent the total cross section of material for two collectives, which will exhibit more flexibility?

I would suspect that if comparably tensioned that the collective with less physical material present would be more flexible.

You (collectively) have failed to explain to me how that isn't the case despite your pompous proclamation suggesting that people have been willing to openly discuss the matter -- again, simply parroting a statment that I have observed to be an urban myth does not move the parroted statement into the realm of truth.

But, you know, that is all barely relevant to the argument I was making ...

AND, how many times do I have to say that I don't care if anyone chooses to build/spec their wheels with double butted spokes?

I have described an empirical observation which you can replicate if you want ...

The rest of YOU (collectively) are extending this thread because you are apparently trying to educate me to your way of thinking.

Believe what you want to believe; but, I can tell you it won't change my mind ... and, the loss, if you are correct, is mine.

For the time being, it is still a free country for you to do & think as you -- or, I -- choose.

BTW. Were you (fish156) one of the people who wanted to know about tempered aluminum bicycle frames? Klein and Cunningham both tempered their frames. You've heard of them, right? I didn't pursue that thread at the time because it seemed better to let it fade into the ether without further embarrassing you, et al, at the time.

Be the defender of the faith -- the ayatollahs would be proud of you.
 

fish156

New Member
Mar 26, 2005
262
0
0
alfeng said:
You are kidding, right?

What? Because I refuse to bow at the feet of the god of double butted spokes I am recalcitrant?

I don't see how my failure to embrace what people parrot is an unwillingness to discuss the matter ...

I was asked me to elucidate.

I thought I did.

You clearly have chosen NOT to comprehend what I have said while reading into my statements things I am not saying.

If you don't understand the principle of how a gyroscope works and how it applies to my conclusion, then I have failed to clarify.

Further, I have described an EASY test anyone can do to see how a rim deflects -- simply grab some spokes and notice how the rim is NOT rigid ... oh, gee, I didn't phrase it THAT way, now did I?

Regarding ScienceIsCool's earlier statement with regard to the modulus of elasticity (okay, he just said "modulus"), you ignore the logical conclusion from his abbreviated statement!

That is, if there is X-amount of material, and the cross section of a double butted spokes is 3/4 the cross section of a single gauge spoke (you CAN do the math, can't you?), then doesn't it necessarily follow that the wheel laced with double butted spokes will be more flexible ... if tensioned to comparable spec.

Think about it.

AND, based on what you and others are espousing, motorcycle spoked wheels should be able to use 14-15-14 double butted spokes ... but, they don't. HMMM, I wonder why ...

I have repeatedly stated that I don't expect to convince anyone that straight gauge spokes might be better since it is clearly considered to be an heretical statement.

Where's anyone's proof other than suggesting that so-called experts have said so?

Regarding Schraner, et al. Why would I waste my money-or-time as you have to read misinformation? 1999? Shameful ... as noted, if he wrote his book in 1980 the I would allow him an "out" for originating an urban myth ... since I know Brandt's work predates 1999, is he the originator?

What? Is your idea of "substance" a series of formulas?

Here ... to over-simplify it for you ... compare 32*.75 & 32*1.0.

If the resulting numbers represent the total cross section of material for two collectives, which will exhibit more flexibility?

I would suspect that if comparably tensioned that the collective with less physical material present would be more flexible.

You (collectively) have failed to explain to me how that isn't the case despite your pompous proclamation suggesting that people have been willing to openly discuss the matter -- again, simply parroting a statment that I have observed to be an urban myth does not move the parroted statement into the realm of truth.

But, you know, that is all barely relevant to the argument I was making ...

AND, how many times do I have to say that I don't care if anyone chooses to build/spec their wheels with double butted spokes?

I have described an empirical observation which you can replicate if you want ...

The rest of YOU (collectively) are extending this thread because you are apparently trying to educate me to your way of thinking.

Believe what you want to believe; but, I can tell you it won't change my mind ... and, the loss, if you are correct, is mine.

For the time being, it is still a free country for you to do & think as you -- or, I -- choose.

BTW. Were you (fish156) one of the people who wanted to know about tempered aluminum bicycle frames? Klein and Cunningham both tempered their frames. You've heard of them, right? I didn't pursue that thread at the time because it seemed better to let it fade into the ether without further embarrassing you, et al, at the time.

Be the defender of the faith -- the ayatollahs would be proud of you.
Once again, you fail to back up anything you say with other than your own opinion.

You embarrass me? That's a good one ;-)

Yes, I do remember that thread. When pressed, you launched into homophobic rants. That was most impressive. Here's the link so that anyone who missed your performance in that thread can read it now and see, once again, at how narrow minded you are:

http://cyclingforums.com/t-349544-15-1&highlight=tempering+aluminum.html

Sure, lets see some of your "examples" of aluminum bike frames that have been tempered after welding. Please put up those links. I'm sure we'd all like to see you back up something you claim with some proof.
 

alfeng

Well-Known Member
Jul 23, 2005
6,723
126
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fish156 said:
Once again, you fail to back up anything you say with other than your own opinion.

...

Sure, lets see some of your "examples" of aluminum bike frames that have been tempered after welding. Please put up those links. I'm sure we'd all like to see you back up something you claim with some proof.
Which part of Klein or Cunningham aren't you comprehending as framemakers who tempered their aluminum frames after welding?