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Old 08-12-09, 11:21 AM   #1
Doug64
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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.
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Old 08-12-09, 11:24 AM   #2
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I'd say the 135mm hub could be more stiff (laterally), but not stronger. This assumes the flanges are spaced apart slightly more.
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Old 08-12-09, 11:31 AM   #3
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Originally Posted by Doug64
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.
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Old 08-12-09, 12:48 PM   #4
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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.
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Old 08-12-09, 01:15 PM   #5
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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

Last edited by rydaddy; 08-12-09 at 03:13 PM.
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Old 08-12-09, 02:08 PM   #6
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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.

Last edited by dahoyle; 08-12-09 at 02:15 PM.
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Old 08-12-09, 02:13 PM   #7
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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.
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Old 08-12-09, 02:20 PM   #8
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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. "
"

Last edited by dahoyle; 08-12-09 at 02:34 PM.
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Old 08-12-09, 02:26 PM   #9
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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
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Old 08-12-09, 02:32 PM   #10
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See Above.

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

Run along now.
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Old 08-12-09, 02:35 PM   #11
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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.
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Old 08-12-09, 02:40 PM   #12
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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 ....
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Old 08-12-09, 02:44 PM   #13
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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.
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Old 08-12-09, 02:49 PM   #14
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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
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Old 08-12-09, 02:51 PM   #15
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Uh, I may be way off here
Correct

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Sheldon Brown is not the person who gets to determine what the definition of strength is.
Is Jobst Brandt an acceptable authority then?

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One quick question, and I'm done.
Your question has nothing to do with what I said.

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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.
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Old 08-12-09, 02:52 PM   #16
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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.
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Old 08-12-09, 02:53 PM   #17
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Is Jobst Brandt an acceptable authority then?


Uh,,, not in this case.
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Old 08-12-09, 02:55 PM   #18
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Wait. I thought you were done if I answered.
I lied. this is fun.
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Old 08-12-09, 02:56 PM   #19
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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.
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Old 08-12-09, 02:58 PM   #20
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If this discussion does not remain civil I'll be getting out the mop and bucket.
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Old 08-12-09, 02:58 PM   #21
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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.
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Old 08-12-09, 03:01 PM   #22
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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.
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Old 08-12-09, 03:11 PM   #23
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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.
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Old 08-12-09, 03:21 PM   #24
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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.
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Old 08-12-09, 03:25 PM   #25
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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.
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