chorlton

I keep coming back to my program for doing this stuff... because I can. Most recently I have added the ability, perhaps wasted, to deal with butted/non-butted spokes and work out the relative tensions, ratio of sines, as well as take into account elongation of the spokes when under tension.

In respect of elongation then, assuming I have got the sums right, it really does not seem to matter much. Perhaps 1/10th of a millimetre. Slightly disappointed and still concerned I might have the sums wrong there. One thing that does appear to drop out of things is relative tension for same side spokes.

Reading about the place it would seem that the goal is for equal tension in same side spokes but apparently due to tolerances and stuff you cannot achieve it within 'mumble' percent.

Perhaps another and more realistic reason why you are not going to achieve it is that same side spokes exit the flange on opposite sides and therefore at different axial angles because of the width of the flange.

Picture: This is a nominal 700C front wheel with the added bells and whistles. I have overdone the precision. Anyway it has some butted spokes. The Radial and Axial angles are for the Nipples and some trigonometry rule says I can transpose them to the hub.

Target tension was/is 130KGf with a Youngs Modulus of 180GPa/m^2. Program checks for spoke with smallest angle and then works out the rest based on that. Inner spokes on either side have the smallest angle and end up at 130KGf.

Outer spokes on the same side, apart from diving into the flange, have the larger angle and... end up at 112.66KGf. If and when I take out the dive into the flange that will get lower.

Of itself that seems/is significant and suggests that aiming for equal tension on same side spokes, assuming I read other people's words correctly, is perhaps a fallacy that should not necessarily be dismissed for reasons of accuracy of measurment but is in fact 'a real thing'.

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cny-bikeman

WAY too much time on your hands...and yet you don't address interlacing, including on your diagram. But even if you accomplished a perfect model, what good is it, given that indeed there will be variation in tension even on a new wheel? Of course worrying about even tension on a used wheel is not just useless, it can be counterproductive.

FBinNY 

The only fallacy here is your assumption that lines from inside or outside the flange would make a difference.

Two reasons why they don't.

1- from the point of view of bracing angle, the key is the angle at the rim, not the hub. Since the spokes are woven over under at the last cross, their line to the rim only differs by the effect of 1/2 a spokes section, or virtually zero.

2- more important is the net torque consideration. The sum of tensions of all the clockwise spokes must equal the sum of all the counterclockwise spokes. This is immutable according to Newton's Laws, and if it were not the case, the hub would rotate relative to the rim until it were.

So, respectively, and not knowing what you're trying to prove, you're all wet. This is an example of knowing a lot and understanding nothing. Like with an impressionist painting, you have to forget about the dots, and step back to see the picture.

chorlton

I see the big boys are out.

It is three cross.

However you are quite correct that I have not as yet included the effects of interlacing. No doubt you know how that will affect things which could have made your contribution slightly valuable if you would have explained but I guess that since you have not explained your interjection is worthless.

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chorlton

One Hook. Two big fish. I am quite surprised how fast those big boys hit the bait.... NOT.

I almost get 1) in as much as it adds or subtracts from the axial angle although you seem to suggest the effect is minimal. Presumably you are saying CNYBikeMan is wrong. BTW as per my original post the angle used is the axial nipple angle at the rim which appears to agree with your insisted criteria but... nominally speaking, the axial angle at the rim/nipple is the same as that at the hub.

That's one of those trigonometry things you know so much about.

In respect of 2) you seem to be confusing the axial angle with the radial angle. Perhaps you should try to read harder before diving in and calling everyone else wet just because you come from New York. Newton is not immutable, as demonstrated by Einstein, but if you want to quote him pick Law 1) rather than general quoting just coz it makes you sound right.

That's fine. we've met before. I still have no idea why you feel so threatened.

cny-bikeman

Imbuing someone else's discussion of physical phenomena with their presumed emotion is difficult, and probably ill-advised when one perhaps has a preconceived notion.

IK_biker

Besides your wrong assumptions already addressed by FBinNY, the modulus of elasticity is measured in Pa, and 180 GPa seems like an acceptable ballpark figure.
It is not measured in "GPa/m^2".

cny-bikeman

FB is threatened and my contribution is worthless. I'm waiting with bated (or maybe baited, as I'm just a fish) breath to hear your pronouncements as to other contributors' inner emotions and value.

chorlton

Person States A). When person is asked about A) person talks about thing not associated with A). Conclusion... Person does not know about A).

Of course I should be grateful for the electricity you have saved me by sending black pixels.

FBinNY 

Sorry that you're offended.

You posted a false assumption, and I corrected it. Maybe I was a bit harsh, but you should expect that when you try to make nonsense sound scientific.

As I said, I have no idea what you're trying to prove, but suggest that you leave it in the oven a bit longer before trying to prove that generally accepted knowledge is wrong.

BTW knowing the words doesn't imply understanding. In my second point, there was no confusion of axial and radial angles, since i clearly referenced tortional considerations.

In any case I don't feel threatened, and doubt that CNY does either. However your reference to big guns, and reaction to being corrected has me believing that maybe you do. Keep working at it, READ the posts when folks are trying to correct your errors, and maybe you'll get there.

I don't have any exclusivity on the knowledge I've accumulated over years, and as countless posts prove, I don't mind sharing it freely.

chorlton

Sure... Pile it on. Ignoring my wrong assumptions as misinterpreted by FBinNY... See what I did there?

My 'number', according to you, is right. However I appear to have messed up the units by adding per square metre when Pa is already 1N/m^2 or 1Kg/m^2, unless you are on Mars. I guess I just looked at the top of the tables.

Thank you very much for pointing out my mistake without properly explaining it.

FBinNY 

It's clear that you don't want or appreciate anybody's help, so, I'll spare you.

OTOH if I find misinformation in the future, I may correct it so others don't get misled.

ThermionicScott 

Subscribed.

chorlton

Not at all. As previously suggested I did not expect anything less from you.

I posted a suggestion. You did not correct it. You immediately dived in and tried to rubbish it using Science yourself, Newton, in a misplaced effort to support your lack of point. Common Sophistry.

Generally accepted knowledge is that axial forces are distributed according to the ratio of sine of angles. Of course the author of Spocalc may be wrong. Perhaps you should send him an e-mail.

I have used ratio of sine of angles to demonstrate that the tension associated with same side spokes, without accounting for other factors which no-one else in this thread has really bothered to properly address other than your suggestion that it does not matter in respect of interleaving, is, necessarily, different.

Perhaps you need to read what you wrote again.... Here it is,

Sounds a bit radial to me.

On that one and in respect of other contributors so far I really do believe you do not feel threatened. You just line yourself up and meaninglessly, probably deliberately, attack stuff that of itself may be reasonable but you feel you have the opportunity to do so.

You once asked me 'What do you bring to the table?' and repeatedly thereafter have taken your axe to the table without sharing much more than your axe. That's OK. You call me. I call you.

Bill Kapaun

When I saw 130kgf for a front wheel it pretty much ended any thoughts of the OP's credibility.

FBinNY 

I'm happy to have given you the opportunity to get that off your chest.

Sadly, while you don't like the source or style of the criticism, nor the possible motives of the critic, that doesn't change the facts.

It's very simple, you've built up some sort of analysis, somehow showing that inside head and outside head spokes can't have equal tensions. I've explained that torsional equilibrium requires that they do and will.

So, you believe what you will, I'll believe what I will and anyone who cares will believe what they will.

chorlton

Thanks. You may have noticed I was not asking for help so much as pointing out the possibility that differential tension on same side spokes is a thing.

Still waiting for the correction.

chorlton

Plug in your own number.

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Andrew R Stewart 

So chorlton is a pseudonym of Trump's?


Their manor of rebuttal to facts seem much the same. Andy

chorlton

OK... using your logic then by extension you are suggesting that Drive side and Non Drive side spokes on a dished rear wheel can have the same tension.

Perhaps you should file for a patent on that one.

FBinNY 

Yes, and I was simply pointing out that this was wrong. As for waiting, just open your eyes for a moment since I very clearly explained why it wasn't possible at least twice already.

DiabloScott

An easy proof would be to build a front wheel radial laced, with half innies and half outies on each flange.
That would eliminate any contribution of interlacing, leaving just the angle effect.

chorlton

Good spot. Accuse Hillary of your own indiscretions and get your Fox mates to re-enforce the misdirection . Next up... Godwin.

FBinNY 

I guess that you really do believe that Einstein disproved Newton since you've managed to make a quantum leap from my reference to torsional equilibrium in either flange to equal tensions in both.

Seriously, stop being angry or defensive and open your eyes.

Consider --- the flange has spokes spiraling out in two directions, clockwise and counter-clockwise. The total torque of all the spokes equals zero, so, the sums of all the right pointing spokes has to equal the sum of all the left pointing spokes. Whatever else is happening cannot change this, so your original demonstration of tension difference must be flawed.

One of the most basic rules of engineering logic is that when you've proven an impossibility, you need to check your assumptions.


(that's 3)

FBinNY 

Not quite.

Actually it would be easy to build a radial wheel with every alternating spoke having higher or lower tension, as long as the rim were stiff enough to withstand it. I could do this and "prove" that head inside spokes have higher tension than outer or vice versa.

My proof of equal (average) tension depends on the torsional considerations, which don't exist in a radial wheel.