Lateral strength of bicycle wheels

[Eichers]

Originally Posted by alienator

Is it safe to assume, klabs, that you aren't going to justify your claims about the factors that affect wheel stiffness?

WOW!!! ...
Are you sure that you know even what you are asking, because it is not something that you seem to do yourself! How many wheels have you actually built yourself?

Yes alfeng, essentially bloviating once again proves that the formula you have indicated holds true ...

thanks KL

 

[alienator]

It doesn't take wheel building experience to understand the physics of where stiffness comes from in a wheel. Moreover, there are a lot of wheel builders that aren't alfeng that understand that wheel stiffness doesn't come from spoke tension, including wheel builders at Weight Weenies. You didn't, however, answer the question. I'll make this easier for you by using simpler language: stiffness is the measure of how much structure resists flexion, elongation, compression, or torsion. Since the topic of late is how a spoke contributes stiffness to a wheel, the stiffness of a spoke is then a measure of how much said spoke resists elongation or compression......but we ca rule out compression in the vast majority of wheels since regular spokes aren't loaded in compression. So given that how can increasing the tension on a spoke increase the stiffness that spoke contributes to a wheel? If a spoke has a stiffness, k =10, then the force to elongate that spoke by x distance is F = -10x. Tension is the force acting on that spoke so we'll call that FT = -10x. So let's take two identical spokes. One is tensioned to 50 units and the other to 100 units: FT1 = -50 = -10x1; FT2 = -100 = -10x2. That means spoke 1 elongates -50/-10 = 5 while spoke 2 elongates -100/-10 = 10. Now lets see how much force it takes to elongate each spoke 1 length unit more. 1 more unit would be -k(1) for each spoke, which means the force required to elongate each spoke by one more unit is -10. So how does more tension make a stiffer wheel when it doesn't change how much force is required to move the spoke an additional increment of distance? Further since k, i.e. stiffness, is a constant, how can more spoke tension change a constant? The simple answer is that it can't. Again, spoke tension can change the dynamics of a whelk, but that is very different situation. Nothing definite can really be said about the dynamic response of a wheel to a load without knowing more about the wheel, like the damping ratio for a wheel, since the dynamics are defined by 2nd order ODE. You could reasonably assume that a wheel is over-damped, but that doesn't help much. Again, given that spokes with greater tension don't decrease how much a wheel deflects under a given load compared to wheels with lower spoke tension (again, as mentioned in quite a few of my other posts, the tension does have to be sufficient to prevent the spoke from going slack.) and given that the a spokes actual measure of stiffness, k, doesn't change with tension, how does increasing tension improve stiffness, klabs?

 

[Eichers]

Originally Posted by alienator

It doesn't take wheel building experience to understand the physics of where stiffness comes from in a wheel. Moreover, there are a lot of wheel builders that aren't alfeng that understand that wheel stiffness doesn't come from spoke tension, including wheel builders at Weight Weenies.

You didn't, however, answer the question. I'll make this easier for you by using simpler language: stiffness is the measure of how much structure resists flexion, elongation, compression, or torsion. Since the topic of late is how a spoke contributes stiffness to a wheel, the stiffness of a spoke is then a measure of how much said spoke resists elongation or compression...

No mate, you obviously can't read, so as such whatever is written wouldn't be sufficient for you. I have been mostly been writing about Bracing Angle (BA) and other aspect of wheel building, such as rear wheel torque control, etc.

Your knowledge of wheel building seems to be limited to spoke tension effects because that is the only thing you seem to want to discuss. A wheel is much more than spoke tension.

I do not wish to discuss spoke tension but I am happy for you to ride your hopefully sufficiently tensioned wheels.

So enough of these posts and best to keep your bad Karma (Bias Nature) for your friends and family.

Originally Posted by alienator
... but we ca rule out compression in the vast majority of wheels since regular spokes aren't loaded in compression. So given that how can increasing the tension on a spoke increase the stiffness that spoke contributes to a wheel? If a spoke has a stiffness, k =10, then the force to elongate that spoke by x distance is F = -10x. Tension is the force acting on that spoke so we'll call that FT = -10x. So let's take two identical spokes. One is tensioned to 50 units and the other to 100 units: FT1 = -50 = -10x1; FT2 = -100 = -10x2. That means spoke 1 elongates -50/-10 = 5 while spoke 2 elongates -100/-10 = 10. Now lets see how much force it takes to elongate each spoke 1 length unit more. 1 more unit would be -k(1) for each spoke, which means the force required to elongate each spoke by one more unit is -10. So how does more tension make a stiffer wheel when it doesn't change how much force is required to move the spoke an additional increment of distance? Further since k, i.e. stiffness, is a constant, how can more spoke tension change a constant? The simple answer is that it can't. Again, spoke tension can change the dynamics of a whelk, but that is very different situation. Nothing definite can really be said about the dynamic response of a wheel to a load without knowing more about the wheel, like the damping ratio for a wheel, since the dynamics are defined by 2nd order ODE. You could reasonably assume that a wheel is over-damped, but that doesn't help much.

Again, given that spokes with greater tension don't decrease how much a wheel deflects under a given load compared to wheels with lower spoke tension (again, as mentioned in quite a few of my other posts, the tension does have to be sufficient to prevent the spoke from going slack.) and given that the a spokes actual measure of stiffness, k, doesn't change with tension, how does increasing tension improve stiffness...

Perhaps alfeng or campybob would like to answer this part of your post. They are experienced wheel builders unlike yourself (who has not built any wheels) and myself (but I have built a few wheels - mainly rear wheels, both alloy and CF).

Front wheels tend last a long time due to good BA and no Torque effects (unless you like running into pot holes). Alfeng or campybob can educate of these effects (if they want to).

So, best to address your questions to them from this point on. They both should be able to educate you in the ways of wheel building (if they want to)

Again to remind, do not PM me, ever. I do not need, nor want, your advice, ever...

thanks KL

... make your Significance in Life, good significance and not bad significance, because both have relevance but only one builds good life and good wheels that are worth turning over and over

 

[alienator]

No one said that there wasn't anymore to a wheel than spokes or spoke tension. The point has been to point out that spoke tension is not a factor in wheel stiffness. It's that which you don't understand, despite your vast abilities with fonts of different sizes, klabs. The factors affecting wheel stiffness have been mentioned ad infinitum, but, again, spoke tension is not one of those factors so long as the spokes are tensioned enough that they don't go slack. You'll also note that others have got their knickers all knotted over spoke tension and the fact that it has no bearing on wheel stiffness. Note that those others include you. After all, it was you that mentioned spoke tension was a factor in wheel stiffness. It's something that alfeng repeats. There is nothing else about wheel stiffness that is as misunderstood as how spokes contribute to that stiffness. Again, I've brought up the other factors, too. I'll disregard the rest of your advice.

 

[Eichers]

Mate, you still can't read ... do not direct your posts to me. I am not interested in discussing spoke tension with you nor receiving advice from you.

You have not built any wheels yourself, I get that (and I hope others do, also). Please direct your questions to other very experienced wheel builders, such as alfeng and campybob, who will be able to educate you in the art of wheel building ( if they want to).

thanks KL

 

[dabac]

Originally Posted by Eichers
No mate, you obviously can't read, so as such whatever is written wouldn't be sufficient for you. I have been mostly been writing about Bracing Angle (BA) and other aspect of wheel building, such as rear wheel torque control, etc.

Your knowledge of wheel building seems to be limited to spoke tension effects because that is the only thing you seem to want to discuss. A wheel is much more than spoke tension.

I do not wish to discuss spoke tension but I am happy for you to ride your hopefully sufficiently tensioned wheels.

So enough of these posts and best to keep your bad Karma (Bias Nature) for your friends and family.

Perhaps alfeng or campybob would like to answer this part of your post. They are experienced wheel builders unlike yourself (who has not built any wheels) and myself (but I have built a few wheels - mainly rear wheels, both alloy and CF).

Front wheels tend last a long time due to good BA and no Torque effects (unless you like running into pot holes). Alfeng or campybob can educate of these effects (if they want to).

So, best to address your questions to them from this point on. They both should be able to educate you in the ways of wheel building (if they want to)

Again to remind, do not PM me, ever. I do not need, nor want, your advice, ever...

thanks KL

... make your Significance in Life, good significance and not bad significance, because both have relevance but only one builds good life and good wheels that are worth turning over and over

Generally speaking, torque effects are small compared to the dynamic relaxation occuring when spokes pass through the load affected zone - which themselves can be small enough to be kinda tricky to measure on some wheels.

This is readily tested - although admittedly not under fully realistic conditions - assuming you have a tensiometer, a bike, an immovable object, and a friend.
Number the spokes, note their tension.
Get on the bike, have your friend repeat the measurements and see how spoke tension changes.
Roll the bike up to an immovable object, get on the bike, put some pressure on the down-bound pedal, have your friend repeat the meassurement, note the changes.

 

[Eichers]

Originally Posted by dabac
Generally speaking, torque effects are small compared to the dynamic relaxation occurring when spokes pass through the load affected zone - which themselves can be small enough to be kinda tricky to measure on some wheels.

This is readily tested - although admittedly not under fully realistic conditions - assuming you have a tension meter, a bike, an immovable object, and a friend.
Number the spokes, note their tension.
Get on the bike, have your friend repeat the measurements and see how spoke tension changes.
Roll the bike up to an immovable object, get on the bike, put some pressure on the down-bound pedal, have your friend repeat the measurement, note the changes.

Hi dabac, I really do not wish to discuss spoke tension but you are welcome to do so (but please do not direct any questions, re spoke tension, to me). As far as I am concerned it is better to use as high a spoke tension as possible that the wheel structure (rim/spokes/hub) can safely and durably accommodate :=)

Re your post, are you suggesting that a 1600 watt sprinter flipping the bike from side to side, or a powerful climber stomping on the pedals, does not affect the wheel structure very much?

thanks KL

 

[dhk2]

Originally Posted by dabac

Generally speaking, torque effects are small compared to the dynamic relaxation occuring when spokes pass through the load affected zone - which themselves can be small enough to be kinda tricky to measure on some wheels.

This is readily tested - although admittedly not under fully realistic conditions - assuming you have a tensiometer, a bike, an immovable object, and a friend.
Number the spokes, note their tension.
Get on the bike, have your friend repeat the measurements and see how spoke tension changes.
Roll the bike up to an immovable object, get on the bike, put some pressure on the down-bound pedal, have your friend repeat the meassurement, note the changes.

I like your test idea dabac. Would like to see particularly how the top spokes share the added bodyweight load. Would be fun to check several wheels to learn if different rims and spokes affected the load distribution. Have a friend with a Park tension gauge, will see if he wants to participate. He can run the gauge, I contribute my 95 kg .....that should be enough dead weight for this experiment.

 

[Eichers]

Originally Posted by dhk2
I like your test idea dabac. Would like to see particularly how the top spokes share the added bodyweight load. Would be fun to check several wheels to learn if different rims and spokes affected the load distribution. Have a friend with a Park tension gauge, will see if he wants to participate. He can run the gauge, I contribute my 95 kg .....that should be enough dead weight for this experiment.

Hi dhk2, how do you think this test will assist, re wheel building, or do you simply find it interesting...

thanks KL

 

[dabac]

Originally Posted by Eichers
Hi dabac, I really do not wish to discuss spoke tension but you are welcome to do so (but please do not direct any questions, re spoke tension, to me). As far as I am concerned it is better to use as high a spoke tension as possible that the wheel structure (rim/spokes/hub) can safely and durably accommodate :=)

Re your post, are you suggesting that a 1600 watt sprinter flipping the bike from side to side, or a powerful climber stomping on the pedals, does not affect the wheel structure very much?

thanks KL

I don't have access to a 1600 watt sprinter. All I can say that with my tensiometer, my weight, and my wheels I don't see much happening when I try to pedal the bike through a wall.

Either way the ,most common spoke killer is fatigue, and even the 1600W sprinter or your powerful climber will spend a lot more time simply keeping up than going all out.

 

[Eichers]

Originally Posted by dabac
I don't have access to a 1600 watt sprinter. All I can say that with my tensiometer, my weight, and my wheels I don't see much happening when I try to pedal the bike through a wall.

Either way the ,most common spoke killer is fatigue, and even the 1600W sprinter or your powerful climber will spend a lot more time simply keeping up than going all out.

Hi dabac, no worries and it really doesn't matter. Hopefully the rim, hub, and spoke manufacturers have done sufficient testing to provide us with accurate specifications :=)

Providing the Bracing Angle is around 6 degrees off each hub flange, ie a non disc 100mm OLD front wheel, and we use as high a spoke tension as possible for the spoke lacing and spoke number, ie >= 90 kgf, that the wheel structure (rim/spokes/hub) can safely and durably accommodate, then all should be fine. If the Bracing Angle is around 6 degrees off each hub flange then many of the variables that affect a bicycle wheel, such as Capt Hooks Law, are reduced and some of the variables can even become negligible :=)

The issue is with the current 10/11spd rear wheels whose DS BA is around 3 degrees, or 100mm OLD disc front wheels,. A Bracing Angle of around 3 degrees off each hub flange will not produce a laterally stiff wheel. So to make these wheels laterally stiff the following can be done/used...

• Deep Rims improve BA, but can have cross-wind issues and are generally heavy which has a larger rotational mass effect.
• Large diameter hub flanges improve BA. In this instance at least the extra rotational mass effect is located close to the axle.
• Long DS spokes, usually a virtual/actual 3x/4x/5x/tangential lacing, and short NDS spokes (usually radial or 1x lacing).
• If necessary, use stiff DS spokes and elastic NDS spokes.
• Increase the NDS BA so that the total BA is between 11 to 13 degrees. This comes at the price of low NDS spoke tension, ie. low NDS tension ratio. This requires the DS spoke tension to be very high to ensure that the NDS spoke tension is sufficient.
• The best result though would be if a Bracing Angle of around 6 degrees off each hub flange could be achieved. This is why they are considering increasing the rear OLD to 135mm, which would be the same as the MTB standard. BTW, a 6 degree BA off each hub flange is possible with 10/11spd wheels but it requires a different wheel construction :=)

[*]Reduce the number of NDS spokes, ie. the current 2:1 triplet configurations.
[*]J spokes allow for heads in and heads out lacing flexibility.
[*]Straight spokes allow for easier connection of the spoke head but at the expense of a more complicated hub flange design.

thanks KL

 

[dhk2]

Originally Posted by Eichers
Hi dhk2, how do you think this test will assist, re wheel building, or do you simply find it interesting...

thanks KL

Find it interesting, that's all. The results will shed light on how much loading/unloading occurs on spokes as the wheel rotates normally. Even on smooth roads, the spokes are being stretched and released with every turn of the wheel. The magnitude and distribution of this cyclical loading across the top and bottom spokes would be interesting to know. Hope to check at least two different wheels, one with 28 thin (15/17/15) spokes, another with 20 heavier spokes.

For building a wheel, would still trust the tension specs provided by the spoke and/or rim makers.

 

[alienator]

I like your test idea dabac.  Would like to see particularly how the top spokes share the added bodyweight load.  Would be fun to check several wheels to learn if different rims and spokes affected the load distribution.  Have a friend with a Park tension gauge, will see if he wants to participate.  He can run the gauge, I contribute my 95 kg .....that should be enough dead weight for this experiment. 

You would also have to consider what happens at speed and with different sized road "features." In general, all wheels are pretty damned stiff radially.

 

[alfeng]

Originally Posted by alienator


You would also have to consider what happens at speed and with different sized road "features." In general, all wheels are pretty damned stiff radially.

WOW!!!

What is THAT supposed to mean?

Where are YOUR numbers?

Once again, you demonstrate that you really, REALLY do not understand bicycle wheel construction & are merely tossing out what is basically nonsense in the Real World but which makes perfect sense in your situational world ...

If you had the slightest inkling about why different crossings are used when lacing a traditional bicycle wheel, then you would know that a x4 spoked wheel has more vertical compliance than a x1 (radially) spoked wheel, et cetera.

Well, at least you are pretending to understand that a wheel on the road might act differently from a static, two-dimensional object.

 

[Yvolution]

It's easy to think of the spokes as columns supporting the wheel and helping it retain its shape. But, the "support" that the wheel receives is created by pulling the spokes towards the center of the wheel (tension) rather than pushing out from the center (compression). If you've had the occasion to hold a spoke that was removed from a wheel, you've probably noticed how flimsy it is. You could bend one in half without too much effort. However, if you tried to pull one apart you would not be able to. The "pulling" of the spokes toward the center of the hub is what gives the bicycle wheel its strength.

 

[Eichers]

The mechanical (vector analysis) relationship between spoke tension/bracing angle (BA)/spoke count, re Lateral and Radial stiffness, is quite interesting, especially Lateral stiffness.

• The smaller the BA becomes the smaller the spoke tension lateral force is available to oppose a rims lateral movement but the higher the vertical force available to oppose a rims radial/vertical movement. So, decreasing BA results in less spoke tension lateral force availability, which results in smaller amounts of spoke tension lateral force to assist with Lateral stiffness. Hence the reason, re decreasing BA (< 6 degrees and especially as it approaches 0 degrees), that increasing spoke tension will not assist very much with increasing Lateral stiffness.
• OTOH, increasing BA (>= 6 degrees and especially as it approaches 12 degrees) means that increasing spoke tension will assist Lateral stiffness more and more, because there is more spoke lateral tension force available to assist with Lateral stiffness. The benefit of increasing BA is that lower spoke tension is required to achieve the same Lateral stiffness although the opposite is the effect on Radial/Vertical stiffness.
• Think of Spoke count as adding each spokes lateral tension force together to give a Total spoke lateral tension force for the wheel build. This is why increasing Spoke count will assist with Lateral stiffness (and Radial stiffness).

Of course, the following should also be considered, re Lateral and Radial/Vertical stiffness...

• Rim stiffness/strength.
• Spoke attachment, loose or fixed... usual is loose, ie J-spoke with nipple.

thanks KL

 

[alienator]

Think of Spoke count as adding each spokes lateral tension force together to give a Total spoke lateral tension force for the wheel build.  This is why increasing Spoke count will assist with Lateral stiffness (and Radial stiffness).

First, tension is a force, so you can just say "tension". Tension is not a factor in wheel stiffness except in that spoke tension needs to be high enough that a spoke doesn't go slack. The reason more spokes can increase lateral stiffness is because there is more material opposing any deflection. More material means adding more stiffness coefficients, i.e. spring constants, together. The primary source of radial stiffness is the rim itself. If you compare the radial deflection of built wheels, you'll find that range of deflection is much smaller. Heck, it's not just much smaller, it's very small. Of course you won't believe me, so instead read what John Swanson has to say in his paper at his BikePhysics website.

 

[Eichers]

Originally Posted by Yvolution
It's easy to think of the spokes as columns supporting the wheel and helping it retain its shape. But, the "support" that the wheel receives is created by pulling the spokes towards the center of the wheel (tension) rather than pushing out from the center (compression). If you've had the occasion to hold a spoke that was removed from a wheel, you've probably noticed how flimsy it is. You could bend one in half without too much effort. However, if you tried to pull one apart you would not be able to. The "pulling" of the spokes toward the center of the hub is what gives the bicycle wheel its strength.

Hi Yvolution, what are your thoughts on what I posted above, re Bracing Angle, Spoke Count, and spoke tension ... thanks KL

 

[alfeng]

Originally Posted by alienator

It doesn't take wheel building experience to understand the physics of where stiffness comes from in a wheel. Moreover, there are a lot of wheel builders that aren't alfeng that understand that wheel stiffness doesn't come from spoke tension, including wheel builders at Weight Weenies.

You didn't, however, answer the question. I'll make this easier for you by using simpler language: stiffness is the measure of how much structure resists flexion, elongation, compression, or torsion. Since the topic of late is how a spoke contributes stiffness to a wheel, the stiffness of a spoke is then a measure of how much said spoke resists elongation or compression......but we ca rule out compression in the vast majority of wheels since regular spokes aren't loaded in compression. So given that how can increasing the tension on a spoke increase the stiffness that spoke contributes to a wheel? If a spoke has a stiffness, k =10, then the force to elongate that spoke by x distance is F = -10x. Tension is the force acting on that spoke so we'll call that FT = -10x. So let's take two identical spokes. One is tensioned to 50 units and the other to 100 units: FT1 = -50 = -10x1; FT2 = -100 = -10x2. That means spoke 1 elongates -50/-10 = 5 while spoke 2 elongates -100/-10 = 10. Now lets see how much force it takes to elongate each spoke 1 length unit more. 1 more unit would be -k(1) for each spoke, which means the force required to elongate each spoke by one more unit is -10. So how does more tension make a stiffer wheel when it doesn't change how much force is required to move the spoke an additional increment of distance? Further since k, i.e. stiffness, is a constant, how can more spoke tension change a constant? The simple answer is that it can't. Again, spoke tension can change the dynamics of a whelk, but that is very different situation. Nothing definite can really be said about the dynamic response of a wheel to a load without knowing more about the wheel, like the damping ratio for a wheel, since the dynamics are defined by 2nd order ODE. You could reasonably assume that a wheel is over-damped, but that doesn't help much.

Again, given that spokes with greater tension don't decrease how much a wheel deflects under a given load compared to wheels with lower spoke tension (again, as mentioned in quite a few of my other posts, the tension does have to be sufficient to prevent the spoke from going slack.) and given that the a spokes actual measure of stiffness, k, doesn't change with tension, how does increasing tension improve stiffness, klabs?

Oh!?!

Apparently, alienator was rejuvenated by dhk2's calculations enough so that we again have to deal with alienator's low reading comprehension (aka "listening") followed by a further expository bloviation where an inability to use "critical thought" or "reason" as they are understood in the Real World vs. in his dystopian situational world being foisted upon us as having been supposedly derived through the "scientific method" ...

Here, once again, YOU begin your rant with a false premise as a "given" whereby you unilaterally declare "that spokes with greater tension don't decrease how much a wheel deflects ...".

Worse, yet, due to your poor reading comprehension + your inability to comprehend the data in a matrix, we see here another example of your inability to demonstrate a "listening" (again, THAT would be "reading" what is in front of you in our non-oral Forum) ability beyond the voices which are apparently in your head AND we now see that you are suggesting that 'I' have been stating that a spoke's tension is the primary factor which affects the lateral stiffness which a bicycle wheel will have ...

So, in your schizophrenic confusion you are now suggesting that 'I' have been suggesting that spoke tension alone (?) has an effect on a wheel's lateral strength (where strength is resistance to lateral deflection) when it has ALWAYS been my contention that if a person wants a "stronger" wheel (again, one which will resist deflection) that s/he will choose straight 14g spokes laced x3 on the driveside & x2 on the non-driveside rather than a wheel laced with double-butted 14-15-14 spokes.

Of course, most-if-not-all of the followers of what I have previously referred to as the "religion of double-butted spokes" apparently believe that lacing a rear wheel x3 on both sides is a requisite part of the fore mentioned religion ...

• Why don't ALL wheel builders use asymmetrical crossing?

• Simply stated, it (certainly) takes (me) MORE TIME to use an alternate crossing pattern on the non-driveside because you either have to have to think about it OR have a wheel which you previously laced with the alternate crossing pattern as a template ...

Your inability to understand that a double-butted 14-15-14 gauge spoke has less lateral resistance to deflection at 100 kgf than a straight 14g spoke fabricated from the same material at 100 kgf speaks volumes to your lack of "critical thought" with an incorrect belief that 'I' am saying that a spokes tension, alone, affects a wheel's lateral strength.

OR, are you now going to say that "of course a thinner spoke is more easily deflected" despite your repeated bloviationg about Hooke's Law?

Because, as you have been presenting Hooke's Law in a linear analysis in the wrong Axis, you have been addressing a straight 14g spoke to be the same in a wheel as a double-butted 14-15-14 spoke (which is presumably of the same material) ...

And, extrapolating YOUR statement would logically suggest that a piece of rebar (if it were made of the same material) would have the same ability to resist lateral deflection.

What say you, now?!?

Your insistence that Hooke's Law is directly applicable to analyzing the lateral stiffness which a bicycle wheel will have via an analysis in the wrong axis reaffirms that ...

​

alienator apparently doesn't know the difference between Hooke's Law and Captain Hook.​

​

Regardless, if you are going to pretend that Hooke's Law is applicable, then you would need to base your calculations on the Conic cross section of the different spokes ...

BUT, while the length of the spokes might vary by a small enough percentage to be negligibly different, if the double-butted 14-15-14 spoke's cross-section is approximately only 90% of the that of the straight 14 gauge spoke's cross-section, then the resultant calculation will not be a small amount....

The Park Tool tensiometer's matrix suggests a difference of roughly 76+ %.

If you don't like the precision of the Park Tool & matrix, then at the very least, THAT minimally suggests a difference of 81% ...

81% is hardly a small amount in the Real World.
Regardless, YOU are absolutely incorrect when you bloviate that a spoke merely needs to have enough tension so that it does not go slack ...

And, if one allows that your suggestion of "50 units" vs. "100 units" is translatable to "50 kgf" and "100 kgf" then it is really, REALLY TOO BAD that you don't still live in the Tucson-area-and-environs because if you were able to convince your AZ wheelbuilder (or, if you were to finally venture to actually build a set of wheels) to lace a set of wheels for you which were only tensioned to 50 kgf and then ride up to the summit of Mt. Lemmon (if you ever did so in the past ... OR, as far as you can go where you encounter switchbacks or curves which are taken in excess of a modest 20mph) then I'll bet you have a different song to sing after the descent on bicycle wheels whose spokes are laced at only 50+ kgf.

Hey, why don't you detension your current wheels ...

then see how you subsequently feel about a wheel's lateral strength [resistance to lateral deflection] on a roadway which you are familiar with that has some moderately high speed left-right turns in succession!

 

[alfeng]

Originally Posted by alienator


First, tension is a force, so you can just say "tension". Tension is not a factor in wheel stiffness except in that spoke tension needs to be high enough that a spoke doesn't go slack. The reason more spokes can increase lateral stiffness is because there is more material opposing any deflection. More material means adding more stiffness coefficients, i.e. spring constants, together.

The primary source of radial stiffness is the rim itself. If you compare the radial deflection of built wheels, you'll find that range of deflection is much smaller. Heck, it's not just much smaller, it's very small. Of course you won't believe me, so instead read what John Swanson has to say in his paper at his BikePhysics website.

Unless Swanson re-did his measurements with meaningful weights, his conclusion is meaningless.