Bicycle Mechanics - Wheel Strength Question

Can anyone tell me why (if) a rear wheel built with a 135mm hub would be stronger than a wheel built on a 130mm hub? This is assuming all thing are essentially equal: spokes, rims, axle diameter, hub flange thickness? Looking at the Shimano specs, the 130mm road hub axles and bearings are the same size as the 135mm mountain's axles and bearings. I've measured the flanges on our road bike hubs, and they are the same thickness as our mountain bike hubs. I have heard less dishing, but that seems like it would just be lateral rigidity.

I'd say the 135mm hub could be more stiff (laterally), but not stronger. This assumes the flanges are spaced apart slightly more.

the 130mm road hub axles and bearings are the same size as the 135mm mountain's axles and bearings.

The axles are not the same size. Looking at Shimano specs, the mountain axles are clearly 146mm, vs. 141mm for road. I would think that the flanges would usually be wider and the spokes would have more of a bracing angle to create a stronger wheel.

I have heard less dishing, but that seems like it would just be lateral rigidity.

Uh, I may be way off here, but isn't lateral rigidity a measure of strength? More lateral rigidity=more strength.

Yeah, that must be it.

Seems pretty straightforward to me.

Uh, I may be way off here, but isn't lateral rigidity a measure of strength? More lateral rigidity=more strength.

Yeah, that must be it.

Seems pretty straightforward to me.


Not the same at all. Strength is the amount of force the wheel can take before one or more spokes go slack. Wheel strength is largly influenced by the rim choice, # of spokes and spoke tension. Stiffness is a measure an objects resistance to deflection by an applied force. Lateral stiffness is influenced mostly by the flange spacing at the hub, rim choice, and the number (and thickness) of spokes - but not spoke tension.

A strong wheel is one that is tensioned as high as possible without exceeding the limits of the rim. It is true that a wheel with less dish is stronger, since the NDS spokes are tensioned closer to the DS tension and will take more external force to go slack.

Some geeky wheel info if you're interested....

http://www.sheldonbrown.com/rinard/wheel/index.htm

http://www.myra-simon.com/bike/wheels.html

Sorry, but you are just flat wrong.

I didn't say that lateral stiffness was the only measure of strength, just that it was a measure of strength.

Strength is a combination of all the elements of design, not just one, as you seem to think. Your definition of strength has absolutely no basis in reality.

I'll put it in simple English,

If you have two wheels that are identical in all aspects, other than lateral stiffness, then the one which has greater lateral stiffness, is in fact, the stronger wheel.

I don't need to look at a website, no matter how revered it may be to know the definition.

Thanks for playing.

Sorry, but you are just flat wrong.

I didn't say that lateral stiffness was the only measure of strength, just that it was a measure of strength.

Strength is a combination of all the elements of design, not just one, as you seem to think.

I'll put it in simple English,

If you have two wheels that are identical in all aspects, other than lateral stiffness, then the one which has greater lateral stiffness, is in fact, the stronger wheel.

I don't need to look at a website, no matter how revered it may be to know the definition.

Thanks for playing.


I'll go ahead and let you think you're right. ;)

I'll go ahead and let you think you're right. ;)


Meaning that there is nothing in the statement that you can refute, from an engineering standpoint, or just the basic definition.

Strength :
Definition: Power to resist force; solidity or toughness; the quality of bodies by which they endure the application of force without breaking or yielding; in this sense opposed to frangibility; as, the strength of a bone, of a beam, of a wall, a rope, and the like.

Since you use those particular sites as the basis of your argument, rather than the common definition, allow me to quote directly from the second, and see if you are going to tell them that they are wrong. You can't have it both ways.

"Another thing that affects the strength of the wheel is the amount of dishing. This is mainly a problem with the rear wheel, although it is an issue with front wheels with disc brakes as well. On a normal front wheel, you have flanges equidistant from the center of the hub, and spokes go from these flanges to the rim. The spokes coming from each flange go at the same angle to the rim. On the other hand, consider a rear wheel. The right side of the hub has to have room for lots of sprockets, so the right side flange is much closer to the center than the left side flange. Thus if the rim is aligned with the center of the hub as it should be, the left side spokes will be more slanted than the right side spokes (in some cases the right hand spokes are nearly vertical). Thus, in order to keep the rim in the center, the right hand spokes will have to be much tighter than the left hand spokes. When the wheelbuilder is tensioning the wheel, the right side spoke will reach their maximum tightness long before the left spokes will. It is the weakness of the less-tight left hand spokes that makes a highly dished wheel (one where the angle difference between the left and right spokes is great) less strong and less durable than a wheel with less dish. "
"

Meaning I don't have the time to argue with someone that's not listening (or reading informative links related to bicycle wheels).

The first sentence of link #1...

"It must be emphasized that wheel stiffness is not wheel strength, and in fact may be unrelated to it. I am measuring stiffness, not strength."

-Sheldon Brown

See Above.

As I said, Sheldon Brown is not the person who gets to determine what the definition of strength is.

Run along now.

Since you use those particular sites as the basis of your argument, rather than the common definition, allow me to quote directly from the second, and see if you are going to tell them that they are wrong. You can't have it both ways.

"Another thing that affects the strength of the wheel is the amount of dishing"
"


I'd like to hear your explanation as to why dishing affects wheel strength. Hint: I already said why.

One quick question, and I'm done.

If two objects have all the same characteristics, with the exception of one. In that one case, one is measurably more resistant to deflection before failure, Then you are saying they both have the same strength.

Please, I want you to say that, in those words, so that we may all ridicule you ....

One quick question, and I'm done.

If two objects have all the same characteristics, with the exception of one. In that one case, one is measurably more resistant to deflection before failure, Then you are saying they both have the same strength.

Please, I want you to say that, in those words, so that we may all ridicule you ....

You really need to see a doctor about that cranial-rectal injection from which you are suffering.

You really need to see a doctor about that cranial-rectal injection from which you are suffering.

Yeah, it's been a real problem.

On the other hand, I am not the one who is arguing from a totally unsupportable position.

I quoted directly from the very site he was using as a reference, and guess what, the quote contradicts his argument.

Please allow me my little third grade response.

He started it:roflmao2::roflmao2::roflmao2:

Uh, I may be way off here

Correct


Sheldon Brown is not the person who gets to determine what the definition of strength is.

Is Jobst Brandt an acceptable authority then?


One quick question, and I'm done.

Your question has nothing to do with what I said.


I want you to say that, in those words, so that we may all ridicule you ....

Wait. I thought you were done if I answered. :cry:

I quoted directly from the very site he was using as a reference, and guess what, the quote contradicts his argument.


If you had an inkling of understanding then you would realize there is no contradition whatsoever.

Is Jobst Brandt an acceptable authority then?





Uh,,, not in this case.

Wait. I thought you were done if I answered. :cry:

I lied. this is fun.

Can anyone tell me why (if) a rear wheel built with a 135mm hub would be stronger than a wheel built on a 130mm hub? This is assuming all thing are essentially equal: spokes, rims, axle diameter, hub flange thickness? Looking at the Shimano specs, the 130mm road hub axles and bearings are the same size as the 135mm mountain's axles and bearings. I've measured the flanges on our road bike hubs, and they are the same thickness as our mountain bike hubs. I have heard less dishing, but that seems like it would just be lateral rigidity.

With all things being equal there is not going to be a lot of difference in wheel strength between a 135 mm and 130 mm hub... the size of the rim used will have a greater effect as smaller wheels are stronger.

This is why 26 inch wheels are still the weapon of choice for mountain bikers and utilitarian purposes... 29 inch mountain bikes and cross bikes use a 700c rim and the wheels have to be built to very high specs to withstand the same abuse a 26 inch wheel can take.

To illustrate further ... the 20 inch wheels on my folder are 36 spoke... to get a 700c wheel to be this strong you would need to build a 48 spoke wheel.

A lack of lateral stiffness is a serious issue with any wheel and with dishing, the closer the tension is between the non drive and drive side spokes the better.

A zero dish wheel has equal spoke tensions which is the ideal for building a really strong wheel but a compromise has to made when one uses derailer gears.

Moderators note:

If this discussion does not remain civil I'll be getting out the mop and bucket.

Your question has nothing to do with what I said.

I'd say the 135mm hub could be more stiff (laterally), but not stronger



Uh, yeah, it is pretty much directly in response to what you said.

Moderators note:

If this discussion does not remain civil I'll be getting out the mop and bucket.

I haven't found it to be uncivil, seems more like a playful banter. From my perspective anyways.

In any case, there is certainly nothing more I can add, so I'll bow out now.

Hi guys,
I meant to stimluate a healthy discussion about wheel strength, not start an arguement! Maybe I could give you a little background on the question which would really help me out. My touring bike currently has 130 mm rear dropouts. I'm in need (at least I think I do; the present wheels made it acoss the US without any trouble) of a stronger wheel for a pretty demanding tour. I have been vacillating about getting a new bike with the 135mm dropouts or getting a good set of wheels built for my current bike. The real question is: Is the cost of getting a new bike (which has run-of-the-mill wheels) going to give me a better ride than just upgrading my present wheel set? Put the strength/stiffness/etc in the context of a loaded touring bike on mostly paved roads. Thanks for the info so far.

Hi guys,
I meant to stimluate a healthy discussion about wheel strength, not start an arguement! Maybe I could give you a little background on the question which would really help me out. My touring bike currently has 130 mm rear dropouts. I'm in need (at least I think I do; the present wheels made it acoss the US without any trouble) of a stronger wheel for a pretty demanding tour. I have been vacillating about getting a new bike with the 135mm dropouts or getting a good set of wheels built for my current bike. The real question is: Is the cost of getting a new bike (which has run-of-the-mill wheels) going to give me a better ride than just upgrading my present wheel set? Put the strength/stiffness/etc in the context of a loaded touring bike on mostly paved roads. Thanks for the info so far.


If that is the quandry, then there are a few questions. What is the frame material of your current bike. If I was considering having wheels made for it, then if at all possible, I would go the extra step of spreading the stays, and building a 135. All other things being equal, they will be laterally stiffer(stronger) than the 130's. This statement makes the assumption that the hub flanges are 5 millimeters farther apart.

If that is not a possibility, due to frame material, then it simply becomes a question of economics. Would I buy a new bike for the benefits of the slightly stronger wheel? Not unless I had a reasonable certainty that it was necessary for what I had in mind. Given your success so far with what you have, I would say that unless you are going to be changing the load significantly, it seems to be good the way it is.

My vote is get a good set of wheels for the current bike. There are plenty of options. Of course, we all want new bikes too. But if money's an object, the right wheelset will do the job just fine.

I build a lot of touring wheels on 130mm hubs and they have traveled some epic distances and survived some harrowing conditions.

If your bicycle fits well and does what it needs to do I'd upgrade the wheels although... if they made it across the USA with no issues I am guessing they are already fairly good wheels.

Hi guys,
I meant to stimluate a healthy discussion about wheel strength, not start an arguement! Maybe I could give you a little background on the question which would really help me out. My touring bike currently has 130 mm rear dropouts. I'm in need (at least I think I do; the present wheels made it acoss the US without any trouble) of a stronger wheel for a pretty demanding tour. I have been vacillating about getting a new bike with the 135mm dropouts or getting a good set of wheels built for my current bike. The real question is: Is the cost of getting a new bike (which has run-of-the-mill wheels) going to give me a better ride than just upgrading my present wheel set? Put the strength/stiffness/etc in the context of a loaded touring bike on mostly paved roads. Thanks for the info so far.

Of course, this could be just the needed argument to convince your significant other that it is time for a new ride:D:D:D

One quick question, and I'm done.

If two objects have all the same characteristics, with the exception of one. In that one case, one is measurably more resistant to deflection before failure, Then you are saying they both have the same strength.

Please, I want you to say that, in those words, so that we may all ridicule you ....
A bamboo skewer is far stiffer than a bicycle spoke, but that doesn't mean it is stronger.

A bamboo skewer is far stiffer than a bicycle spoke, but that doesn't mean it is stronger.

Wow, I don't have any idea where this nonsense keeps coming from. How does that even relate to what you quoted. Obviously, when comparing a bamboo skewer to a bicycle spoke, then all things are not equal are they?

Once again, I didn't say that it was the only measure of stiffness. I said that all other things being equal, then the wheel with the greater lateral stiffness is the stronger.


Now let's put it to rest once and for all, take 2 identical wheels, the same gauge spokes, identical hubs except that the flanges on one are spread 5mm farther apart. Build 2 wheels. The wheel with the wider spaced flanges are stronger. Is that so hard to comprehend? I hope not.

Thanks for playing. You can pick up your consolation prize from the lady at the door.

Once again, I didn't say that it was the only measure of stiffness. I said that all other things being equal, then the wheel with the greater lateral stiffness is the stronger.

Obviously, when comparing a bamboo skewer to a bicycle spoke, then all things are not equal are they? They are not even wheels.

Now let's put it to rest once and for all, take 2 identical wheels, the same gauge spokes, identical hubs except that the flanges on one are spread 5mm farther apart. Build 2 wheels. The wheel with the wider spaced flanges are stronger. Is that so hard to comprehend? I hope not.

Thanks for playing. You can pick up your consolation prize from the lady at the door.

Wrong. And Wrong. :rolleyes:

then the wheel with the greater lateral stiffness is stiffer
The wheel with the wider spaced flanges is stiffer

Fixed

Fight to the death!

Wrong. And Wrong. :rolleyes:

then the wheel with the greater lateral stiffness is stiffer
The wheel with the wider spaced flanges is stiffer

Fixed

Wrong and wrong. In this case, strength and stiffness can not be separated.

Strength :
Definition: Power to resist force; solidity or toughness; the quality of bodies by which they endure the application of force without breaking or yielding

Therefore, if they are equal in resisting loads in all directions except laterally, then the one which resists greater lateral force before yielding is by definition, Stronger.

Thanks, Money is an object. Even though a new bike would be nice, I think the money spent on a good set of wheels (or at least the back wheel) will meet my needs. I was leaning that way, but needed a little help tilting all the way in that direction. I ride a steel frame Bianchi Volpe, but do not want to spread the dropouts. However, our son races cyclocross on the single speed version of the Volpe, and he crams a 135mm hubbed wheel in there without too much trouble. His bike is 2 years newer than mine, but it looks about ten years and two train wrecks older!

Don't confuse wheel stiffness with strength. You can compare it to materials properties of Young's Modulus versus yield strength versus ultimate strength.

As for comparing 130mm versus 135mm wheels, the missing data the OP failed to provide is the flange-spacing. Without it, we are talking about nothing relevant.

Fight to the death!

"No. To the pain." :D

Don't confuse wheel stiffness with strength. You can compare it to materials properties of Young's Modulus versus yield strength versus ultimate strength.

As for comparing 130mm versus 135mm wheels, the missing data the OP failed to provide is the flange-spacing. Without it, we are talking about nothing relevant.


I am not confusing it. I am deliberately ruling it out by stating that all other things remain constant.

I am not confusing it. I am deliberately ruling it out by stating that all other things remain constant.
It doesn't matter if all other things are constant. You can have something that is flexible that resists force more than something that is stiff. Stiff just means it won't bend. That does not preclude it from snapping. It is entirely possible to have something that will snap under a lighter load that another thing will bend at.

The definition you posted yourself said breaking OR yielding. As long as an item returns to its original form without an additional force, it hasn't broken or yielded.

Example: Track sprinters like stiffer wheels because they don't want them to go all noodley when they are trying to put power to the ground and gain traction. Those stiffer wheels actually break more spokes than the noodley ones because the wheels refuse to flex, so they snap instead of returning the load. In such a case, stiffer does not equal stronger... unless you consider a wheel more likely to break to be stronger.

It doesn't matter if all other things are constant. You can have something that is flexible that resists force more than something that is stiff. Stiff just means it won't bend. That does not preclude it from snapping. It is entirely possible to have something that will snap under a lighter load that another thing will bend at.

The definition you posted yourself said breaking OR yielding. As long as an item returns to its original form without an additional force, it hasn't broken or yielded.

Example: Track sprinters like stiffer wheels because they don't want them to go all noodley when they are trying to put power to the ground and gain traction. Those stiffer wheels actually break more spokes than the noodley ones because the wheels refuse to flex, so they snap instead of returning the load. In such a case, stiffer does not equal stronger... unless you consider a wheel more likely to break to be stronger.


Wrong again. Once again you pick an argument in which, all things are obviously not equal. The argument involving the sprinter wheel is invalid, because it is a totally separate entity, and in now way is comparable. The spoke tension is not equal, for one thing, since that is how they in fact change the stiffness of the wheel. So, to make it stiffer, they took the spokes closer to yield. In the case of wider flanges, on a drive hub, you can get away with less tension on the drive side. Just one more reason why it is stronger.

This is really getting ridiculous.
I don't know how hard it is to just admit that the wider hub flanges make a stronger wheel, if all else is equal. It is simple physics.

Wrong again. Once again you pick an argument in which, all things are obviously not equal. The argument involving the sprinter wheel is invalid, because it is a totally separate entity, and in now way is comparable. The spoke tension is not equal, for one thing, since that is how they in fact change the stiffness of the wheel. So, to make it stiffer, they took the spokes closer to yield.
Incorrect. Higher tension does not make a wheel stiffer.
http://www.sheldonbrown.com/rinard/wheel/index.htm



In the case of wider flanges, on a drive hub, you can get away with less tension on the drive side. Just one more reason why it is stronger.

Agreed. Even tension makes a stronger wheel.




This is really getting ridiculous.
I don't know how hard it is to just admit that the wider hub flanges make a stronger wheel, if all else is equal. It is simple physics.
I'm not arguing that a wider hub doesn't make a stronger wheel. All I said was that stiff does not automatically equal strong. It can in the right circumstances, but not always. Stiff and strong are not mutually exclusive. That is all I was saying. Anything else you inferred from it is from your inability to comprehend what you are reading.

Do you now get that you are arguing against something I never said? My only argument is "it's strong because it's stiff" is not valid. You're right that it's stronger, but for a reason slightly more complex than what you stated.

Incorrect. Higher tension does not make a wheel stiffer.
http://www.sheldonbrown.com/rinard/wheel/index.htm



Agreed. Even tension makes a stronger wheel.



I'm not arguing that a wider hub doesn't make a stronger wheel. All I said was that stiff does not automatically equal strong. It can in the right circumstances, but not always. Stiff and strong are not mutually exclusive. That is all I was saying. Anything else you inferred from it is from your inability to comprehend what you are reading.

Do you now get that you are arguing against something I never said? My only argument is "it's strong because it's stiff" is not valid. You're right that it's stronger, but for a reason slightly more complex than what you stated.

Again, go back and re-read the entire thread, if you are still confused. I never said that stiffer automatically equaled stronger. I never inferred that stiffer automatically inferred stronger. I limited my statement to a single instance, where it could be said that all other forces and material strengths were pretty much equal, in that the only thing changed is the distance between the flanges on a hub. I don't know where bamboo comes into it or any of the rest of it.

And yes, if you make the statement that all other things are equal, then the item which resists deflection is the stronger.

Again, go back and re-read the entire thread, if you are still confused. I never said that stiffer automatically equaled stronger. I never inferred that stiffer automatically inferred stronger.

Uh, I may be way off here, but isn't lateral rigidity a measure of strength? More lateral rigidity=more strength.

That sure seems like you're claiming stiffness = strength and that more stiffness = more strength.




And yes, if you make the statement that all other things are equal, then the item which resists deflection is the stronger.
That was my point with the bamboo sticks. It was supposed to be an example but the root idea was lost on your nit picking. The point is deflection means it can be moved from its natural position. Some items can be deflected and yet return to their natural form (resilience) while others will not deflect but would break under the same load instead (brittle). Strength does have a slightly loose definition, so either could be considered stronger than the other, but I'd rather have the wheel that will deflect and then spring back to position than the wheel that will snap because it is too stiff to deflect. For that reason, I would consider whichever wheel is less likely to PERMANENTLY lose its form to be the stronger. Given all other things equal, of course.


But for the purpose of the OP's question, we agree that flanges set further apart help to make a more durable wheel, regardless of our explanations of why.

Well, we can agree on one thing, anyways.

Actually 2, but I'll get into that.

I have come to the conclusion, using my own intellect and analytical thinking (more people around here should try that) that I was mistaken about tighter spokes relating to a stiffer wheel. After careful consideration, I have to admit that was an assumption I was wrong about. I will add, that this revelation only applies to dished wheels, for reasons that i will go into later.

If you look at a transparent cross section of a wheel from the front or rear, the left and right paired spokes form a triangle with the hub as the base. If you preload a pair of spokes a certain amount, they will stretch, microscopically, so they are in effect a pair of springs. If you double the preload on the springs, they will stretch twice as far, but again, it is most likely not measurable. The important thing here is that the opposing forces cancel each other out, so that if you apply 25 lbs to one side, you in effect, add 25 to 0, given a net movement based on that figure.
As long as the spoke tension is equal, it does not matter what the tension is, short of reaching yield strength, because the tensions cancel each other out, leaving 0 at the node. The deflection will always be constant for a given force, so the stiffness of the wheel will remain constant.


The equal spoke tension canceling out is why this only works on dishless wheels.

It may well apply to dished wheels as well, but I will have to do some mental modeling to determine if that is the case. On the surface, it seems likely, but I need to examine the additional variables in play.

That said, it has no impact on my initial statement, which got all this started, and that the issue of spoke tension has no bearing whatsoever on that.

If you have two wheels that are identical in all aspects, other than lateral stiffness, then the one which has greater lateral stiffness, is in fact, the stronger wheel.

How that can deteriorate into a comparison of spokes to bamboo is really beyond me. I know, and have constantly stated that stiffness in and of itself does not imply strength. Something can be very stiff and yet brittle, etc etc. Nowhere did I dispute that fact. All I ever said was that all things being equal, the wheel having wider spread flanges, was stiffer and by definition stronger than an identical wheel with narrower spaced flanges. In that instance, the difference in strength is quite certainly attributed directly to lateral stiffness. The opposite is also true, especially if you take it to extremes. Take a dishless wheel with very closely spaced flanges. You can build a perfectly good wheel that will roll straight and true and strong, but it will fail catastrophically if you apply a side load. In this instance, the only difference is less lateral rigidity, and it is most certainly a weaker wheel.

Of course, my definition strength and weakness are rather unsophisticated. The wheel with the higher likelihood of failure is the weaker wheel.

Apparently that definition is somehow contrary to the Gospel of Sheldon

-
I don't know the mechanics or physics or any other technical aspects of wheels . . . . I do know a great wheel can be built using either a road or mtb spaced hub.

Quality of components being equal ....How the wheel is put together is the most important factor, in my opinion to a wheel that "Stands". There's no substitute for a hand built wheel built by a Professional wheelbuilder, or highly competent amateur.

Of course, my definition strength and weakness are rather unsophisticated. The wheel with the higher likelihood of failure is the weaker wheel.

That's what confuses me. I gave you a few examples where stiffer wheels could break before a more flexible wheel. Shear strength vs. resilient strength. However, your comment "The deflection will always be constant for a given force, so the stiffness of the wheel will remain constant" makes me realize that you may be giving an allowance for the resilience of a wheel and therefore considering it "stiff" as long as it does not permanently deform. In that case, we are in agreement, but I don't consider that to be stiff, just strong. Am I getting that correctly?

Also, I assume when you say "identical in all aspects, other than lateral stiffness" I assume you mean other than the flange spacing variable? Obviously identical wheels would have identical characteristics. I am inclined to agree that the wheel with the wider flange spacing is stiffer and stronger, but it is stronger because the spoke tension is more even (the NDS spokes aren't as low in tension), not because of the added stiffness.

Well, we can agree on one thing, anyways.

Actually 2, but I'll get into that.

I have come to the conclusion, using my own intellect and analytical thinking (more people around here should try that) that I was mistaken about tighter spokes relating to a stiffer wheel. After careful consideration, I have to admit that was an assumption I was wrong about. I will add, that this revelation only applies to dished wheels, for reasons that i will go into later.

If you look at a transparent cross section of a wheel from the front or rear, the left and right paired spokes form a triangle with the hub as the base. If you preload a pair of spokes a certain amount, they will stretch, microscopically, so they are in effect a pair of springs. If you double the preload on the springs, they will stretch twice as far, but again, it is most likely not measurable. The important thing here is that the opposing forces cancel each other out, so that if you apply 25 lbs to one side, you in effect, add 25 to 0, given a net movement based on that figure.
As long as the spoke tension is equal, it does not matter what the tension is, short of reaching yield strength, because the tensions cancel each other out, leaving 0 at the node. The deflection will always be constant for a given force, so the stiffness of the wheel will remain constant.


The equal spoke tension canceling out is why this only works on dishless wheels.

It may well apply to dished wheels as well, but I will have to do some mental modeling to determine if that is the case. On the surface, it seems likely, but I need to examine the additional variables in play.

That said, it has no impact on my initial statement, which got all this started, and that the issue of spoke tension has no bearing whatsoever on that.

If you have two wheels that are identical in all aspects, other than lateral stiffness, then the one which has greater lateral stiffness, is in fact, the stronger wheel.

How that can deteriorate into a comparison of spokes to bamboo is really beyond me. I know, and have constantly stated that stiffness in and of itself does not imply strength. Something can be very stiff and yet brittle, etc etc. Nowhere did I dispute that fact. All I ever said was that all things being equal, the wheel having wider spread flanges, was stiffer and by definition stronger than an identical wheel with narrower spaced flanges. In that instance, the difference in strength is quite certainly attributed directly to lateral stiffness. The opposite is also true, especially if you take it to extremes. Take a dishless wheel with very closely spaced flanges. You can build a perfectly good wheel that will roll straight and true and strong, but it will fail catastrophically if you apply a side load. In this instance, the only difference is less lateral rigidity, and it is most certainly a weaker wheel.

Of course, my definition strength and weakness are rather unsophisticated. The wheel with the higher likelihood of failure is the weaker wheel.

Apparently that definition is somehow contrary to the Gospel of Sheldon


I encourage you to read Jobst Brandt's book. There are no mental models. Only finite element models. I'm not interested in taking this argument any further. Actually the statement I made about your first post was that stiffness is not related to strength. You seem to have a different definition of 'strength' than I do. Mine is based on many of the wheel gurus writings (confirmed by my own engineering intuition). This discussion is based on assumptions that we have no idea to be factual anyway (as DannoXYZ pointed out). We design wheels based on its intended use, and know what components to choose to get what we want out of them. In the end, we have no way of measuring 'strength' anyway.

I encourage you to read Jobst Brandt's book. There are no mental models. Only finite element models.

+10
I have a copy of the book right here, and have read it several times over the years since I bought it.
Strength and stiffness issues are covered exhaustively.

http://www.amazon.com/Bicycle-Wheel-3rd-Jobst-Brandt/dp/0960723668

Can anyone tell me why (if) a rear wheel built with a 135mm hub would be stronger than a wheel built on a 130mm hub?

Yup.

A wheel that's built on a 135 mm hub will have more space between the right side dropout and the centerline of the bike. Assuming you're talking about conventional hubs and not just arguing for arguing's sake, that will result in less difference between the two sides in the spoke braceing angle. That, in turn, will result in less spoke tension difference between the two sides and provide a more reliable wheel.

And that myth just continues to propagate around here.

Here we go again. The difference in spoke tension is not what makes the wheel stronger or weaker in a dished wheel. It is the fact that one side has much less bracing angle.

By using the explanation of difference in spoke tension alone, you totally ignore the obvious. A wheel with closely spaced flanges will fail before a wheel with wider flanges, even if you are talking about a dishless rim. I do not know what is so hard to comprehend about that statement.

Anyone who knows anything about lateral cross bracing or guy wires knows this to be true. I don't understand why it seems so hard to get across, when the same physical principal is applied to a wheel, rather than a bridge or tower span.

The greater the angle holding the load, the less tension is necessary to restrain the load, when a lateral force is applied to it. A tower with guy wires placed at 80 degrees from vertical is will deflect more with a given lateral load, than a tower with guy wires that are 60 degrees from vertical. As the angle increases to near vertical, the force applied to the guy and anchor rise exponentially, for a given lateral load.
On a Bike wheel, excess deflection is a death blow, as it will go beyond it's ability to correct itself, and become a Taco. Prevent that occurance, and you have prevented the Taco.

Simply put, it is not the difference in tension between the two sides, but rather very simple physics as it relates to all structures.

There is a nonrelated article including a chart measuring felt loads of the guys(or spokes, in the case of a bike wheel) as it relates to the angle of the guy.

http://books.google.com/books?id=-6rzSZLM00QC&pg=PA138&lpg=PA138&dq=guy+angle+vs+load+chart&source=bl&ots=t611Gr6wq7&sig=wWIPH44nk7WS3DpEIjw0ybwx3EQ&hl=en&ei=-4OESqK-FYHssQP2mvyTBw&sa=X&oi=book_result&ct=result&resnum=1

The table is on page 137. Of particular interest, is the shape of the curve.

When I say unrelated, I don't mean that the physics don't apply, just that the subject matter is somewhat different.

The difference in spoke tension is not what makes the wheel stronger or weaker. It is the fact that one side has much less bracing angle.


This statement is golden. :roflmao2:

And that myth just continues to propagate around here.

Here we go again. The difference in spoke tension is not what makes the wheel stronger or weaker. It is the fact that one side has much less bracing angle.

By using the explanation of difference in spoke tension alone, you totally ignore the obvious. A wheel with closely spaced flanges will fail before a wheel with wider flanges, even if you are talking about a dishless rim. I do not know what is so hard to comprehend about that statement.

Anyone who knows anything about lateral cross bracing or guy wires knows this to be true. I don't understand why it seems so hard to get across, when the same physical principal is applied to a wheel, rather than a bridge or tower span.
Out of curiosity, what do you believe are the forces and events that lead to a spoke failure on a bicycle wheel? And a rim failure?