Spokes Rubbing

[Yellow Saddle]

I've got proper work to do, to pay the bills, clients chasing. If I've time I'll do something over the weekend.

A force diagram will take you 30 seconds to do. I'll wait until after the weekend. Pardon my cynicism but I've been here before. I already anticipate the lack of a scanner, no access to a drawing program and finally, my "aggressive" style. Prove me wrong.

 

[Salar]

cynicism but I've been here before. I already anticipate the lack of a scanner, no access to a drawing program and finally, my "aggressive" style. Prove me wrong.

You'll be anticipating wrong then and I've nothing to prove. I'll leave it at that.

Office with scanners, printers and plotters from A4 to A1, Drawing and detailing programmes, also 3D packages and numerous latest 2018 analysis programmes.

And,.......lots of drawing paper and even a drawing board.

 

[T675Rich]

So I finally got round to looking at this, the harp test did quickly show which was the offending spoke and it is indeed loose, very loose. I need to get a spoke wrench, then learn how to properly tighten spokes. thanks for putting up with my vagueness, I know I am annoying.

 

[Yellow Saddle]

So I finally got round to looking at this, the harp test did quickly show which was the offending spoke and it is indeed loose, very loose. I need to get a spoke wrench, then learn how to properly tighten spokes. thanks for putting up with my vagueness, I know I am annoying.

Thanks for letting us know. One experiment kills a thousand speculative guesses. Put away the oil, the alternative lacing and soldering iron.

 

[Katherine]

Mod note.
We see that there are some argumentative posts in this thread, by several posters.
Please keep to the original question in the opening post from now on.

 

[Ajax Bay]

My front wheel started making a noise a couple of rides ago after a bit of investigation I think it is a couple of spokes rubbing . . . My question really is what an cause spokes to rub, I assume it is because a spoke is a bit loose, . . . I am just trying to understand what may have caused it.

So I finally got round to looking at this, the harp test did quickly show which was the offending spoke and it is indeed loose, very loose. I need to get a spoke wrench, then learn how to properly tighten spokes. thanks for putting up with my vagueness,

Mod note.
We see that there are some argumentative posts in this thread, by several posters. Please keep to the original question in the opening post from now on.

@Moderators the "original question" in the OP has been answered (with advice) by the OP checking whether any of the spokes are loose (one was). So the further value in this thread, leave the assertion/refutation of the internet forum agressiveness/not suffering fools gladly of the late JB's (that's Jobst Brandt not any other JB around ), is the nature of the support the spokes give a loaded wheel.

One of the (CC 2017) threads that @Yellow Saddle hoped posters might access is this one: Back-wheel-to-avoid-broken-spokes I have linked to Page 4 which finds some resolution.

Some quotes from this (ie not that) thread:

I give you his [JB's] assertion that a hub didn't hang from the spokes above, but stood on the spokes below.

he [JB] patiently explained on many, many occasions how it is that a hub stands on the bottom spokes. To date, this has not been refuted, but proven again and again.

I think we'll just have to disagree about JB. The bottom spokes in a wheel are still under tension.

Call me aggressive, but with that statement you indicate that you don't understand the concept. Read the book again. It is elegant, simple and lucid.
Yes, the bottom spokes are still in tension, but in less tension that what they were before they were (slightly) compressed. A reduction in tension does not imply out-of-tension.

I believe that Ian and YS both know their stuff (even if they disagree about JB's style) on wheel structure and loading.
The confusion that seems to be generated is one of the use of English words like "hang" and "stand".
Considering a spoked wheel normally loaded (ie with a rider atop), most people consider that a spoke (still) in tension, as the spoke at 6 o'clock still is, cannot be consider to support a compressive load. So JB's assertion that the hub "stood on the spokes below" is incompatible with the general definition of "stand/stood".

@Yellow Saddle was content with these articulations (in the thread linked above):
@adscrim said (my emboldening):
"Under load there is a change in tension on the spokes in the 'load area'. They compress. There is no noticeable change in tension in the spokes above the 'load area'. They don't show any additional extension. Because of this we stay the hub is 'standing' on the lower spokes. However, the hub isn't really standing on the lower spokes as it wouldn't be able to remain up [if] the rest of the wheel structure was removed (think wooden wheels with actual columnar spokes bearing the load). In the same way the hub wouldn't be able to remain up if only the top spokes were in play - I assume the light weight rims we use would collapse. So the hubs neither hangs nor stands but utilises the whole wheel structure and wouldn't work without all the elements of that structure"
@Yellow Saddle agreed (his emboldening): "You are absolutely right in your description. You'll notice that I always use "stand" within quotations since there is no single word I can think of to to replace " So the hubs neither hangs nor stands but utilises the whole wheel structure and wouldn't work without all the elements of that structure."

@the snail : "there is an increase in tension in the other spokes, small, and presumably insignificant in terms of fatigue though."
@Yellow Saddle : "Yes, it is not strictly true but I always hesitate to introduce it early on. People find the "stand on the bottom spoke" concept difficult to digest as it is. The tension in spokes outside the load affected zones do change every so slightly with each cycle and the reason for that is the slight change in overall rim shape when it gets compressed (flattened at the bottom)."

The surprising point to me is that the maximum tension on a loaded wheel is at the edges of load affected zone rather than in the upper part of the wheel, which makes sense as the rim is straightened out so that it is closer to the hub at the bottom and further away at either side. Sort of like a flat tyre which bulges out next to the contact point.

So it's reasonable (and accurate) to say that a loaded hub does not "hang" on the top spokes and equally reasonable to say that a loaded hub does not "stand" on the bottom spokes. Perhaps we could agree that "the hub neither hangs nor stands but utilises the whole wheel structure"?

 

[raleighnut]

@Moderators the "original question" in the OP has been answered (with advice) by the OP checking whether any of the spokes are loose (one was). So the further value in this thread, leave the assertion/refutation of the internet forum agressiveness/not suffering fools gladly of the late JB's (that's Jobst Brandt not any other JB around ), is the nature of the support the spokes give a loaded wheel.

One of the (CC 2017) threads that @Yellow Saddle hoped posters might access is this one: Back-wheel-to-avoid-broken-spokes I have linked to Page 4 which finds some resolution.

Some quotes from this (ie not that) thread:




I believe that Ian and YS both know their stuff (even if they disagree about JB's style) on wheel structure and loading.
The confusion that seems to be generated is one of the use of English words like "hang" and "stand".
Considering a spoked wheel normally loaded (ie with a rider atop), most people consider that a spoke (still) in tension, as the spoke at 6 o'clock still is, cannot be consider to support a compressive load. So JB's assertion that the hub "stood on the spokes below" is incompatible with the general definition of "stand/stood".

@Yellow Saddle was content with these articulations (in the thread linked above):
@adscrim said (my emboldening):
"Under load there is a change in tension on the spokes in the 'load area'. They compress. There is no noticeable change in tension in the spokes above the 'load area'. They don't show any additional extension. Because of this we stay the hub is 'standing' on the lower spokes. However, the hub isn't really standing on the lower spokes as it wouldn't be able to remain up [if] the rest of the wheel structure was removed (think wooden wheels with actual columnar spokes bearing the load). In the same way the hub wouldn't be able to remain up if only the top spokes were in play - I assume the light weight rims we use would collapse. So the hubs neither hangs nor stands but utilises the whole wheel structure and wouldn't work without all the elements of that structure"
@Yellow Saddle agreed (his emboldening): "You are absolutely right in your description. You'll notice that I always use "stand" within quotations since there is no single word I can think of to to replace " So the hubs neither hangs nor stands but utilises the whole wheel structure and wouldn't work without all the elements of that structure."

@the snail : "there is an increase in tension in the other spokes, small, and presumably insignificant in terms of fatigue though."
@Yellow Saddle : "Yes, it is not strictly true but I always hesitate to introduce it early on. People find the "stand on the bottom spoke" concept difficult to digest as it is. The tension in spokes outside the load affected zones do change every so slightly with each cycle and the reason for that is the slight change in overall rim shape when it gets compressed (flattened at the bottom)."


So it's reasonable (and accurate) to say that a loaded hub does not "hang" on the top spokes and equally reasonable to say that a loaded hub does not "stand" on the bottom spokes. Perhaps we could agree that "the hub neither hangs nor stands but utilises the whole wheel structure"?

Far too reasonable a post.

We're waiting for the fight.

 

[Yellow Saddle]

So it's reasonable (and accurate) to say that a loaded hub does not "hang" on the top spokes and equally reasonable to say that a loaded hub does not "stand" on the bottom spokes. Perhaps we could agree that "the hub neither hangs nor stands but utilises the whole wheel structure"?

That's a good attempt at a King Solomon solution but I am not budging by pandering to semantics. Your suggestion is a bit of both. It isn't.

Note, that in a loaded wheel, the tension in the top spokes does not change (given the insignificant rider I don't like to introduce early on in a debate on understanding tensioned wire wheels) but that the tension in the bottom spokes reduce significantly. They never go out of tension, then the wheel would collapse, but they lose significant tension, but the total weight on the loaded hub is absorbed only by the bottom spokes. The number of spokes AT THE BOTTOM which share the load is a function of rim strength. On average, say three. Therefore, if you load the hub with 60kgs and there is 100kg of tension in each spoke before the bike was loaded, the bottom three now have a tension of 80 kgs. The tension in all other spokes remain 100kgs.

If the tension in the top spokes don't change, we can safely say that the hub does not hang on them? Agreed?

If the tension in the bottom spokes reduce, we can safely start to think that the word stand is not all that alien.

A pre-stressed structure works in strange ways. I suggest anyone who really wants to understand this should first learn how modern concrete lintels work, then graduate to bridges (because wheels are supported beams) then to wheels.

A force diagram demonstrates the situation nicely. I'm sure I've posted one before.

 

[T675Rich]

My bike went to the LBS as I was having issues with the gears so they fixed the spoke then and the noise has stopped. I asked about what to do if it happens again and was told never to try and fix the spokes myself and to bring it in. People apparently always mess up their wheels trying to fix loose spokes.

 

[mjr]

My bike went to the LBS as I was having issues with the gears so they fixed the spoke then and the noise has stopped. I asked about what to do if it happens again and was told never to try and fix the spokes myself and to bring it in. People apparently always mess up their wheels trying to fix loose spokes.

Sounds a good way to scare up repeat business. Whether it's worth taking it in depends on how much it costs you (both in shop charges and time) and how big the problem is.

I think the thing people most often miss when tightening loose spokes is that once the was-loose spoke starts taking any tension then each of its neighbours needs tightening by half as much, else you'll be changing the trueness of the rim. I'm sure someone will shout at me if I've misremembered that It's also important to spin the wheel after every adjustment and compare the rim position with a pointer strapped firmly to the forks or stays so you can check whether it's both true and round yet. And that's for small adjustments assuming that most of the wheel is reasonably close to correct. Starting from scratch or with too much wrong is beyond me.

Spoke keys are useful but for small adjustments, a small adjustable spanner will usually suffice - it also usually makes it too difficult to tighten/loosen spokes too quickly

 

[Yellow Saddle]

Sounds a good way to scare up repeat business. Whether it's worth taking it in depends on how much it costs you (both in shop charges and time) and how big the problem is.

I think the thing people most often miss when tightening loose spokes is that once the was-loose spoke starts taking any tension then each of its neighbours needs tightening by half as much, else you'll be changing the trueness of the rim. I'm sure someone will shout at me if I've misremembered that It's also important to spin the wheel after every adjustment and compare the rim position with a pointer strapped firmly to the forks or stays so you can check whether it's both true and round yet. And that's for small adjustments assuming that most of the wheel is reasonably close to correct. Starting from scratch or with too much wrong is beyond me.

Spoke keys are useful but for small adjustments, a small adjustable spanner will usually suffice - it also usually makes it too difficult to tighten/loosen spokes too quickly

You did indeed misremember the procedure.

 

[mjr]

You did indeed misremember the procedure.

Be nice if some non-priest could correct it, but until then, I'm sure it's in all good cycling books (so probably not the Haynes Blue Book).

 

[Yellow Saddle]

Be nice if some non-priest could correct it, but until then, I'm sure it's in all good cycling books (so probably not the Haynes Blue Book).

Tell you what, show a quote from just one cycling book that says that. Don't offer poor advice.

 

[mjr]

Tell you what, show a quote from just one cycling book that says that. Don't offer poor advice.

I'm sat at work which is unsurprisingly bereft of books covering wheel-truing. I'll probably keep daring to post stuff from memory without citations, but at least I label it as such, especially when I'm unsure if I've remembered it rightly! At least I attempt to offer advice.

 

[Ajax Bay]

So it's reasonable (and accurate) to say that a loaded hub does not "hang" on the top spokes and equally reasonable to say that a loaded hub does not "stand" on the bottom spokes. Perhaps we could agree that "the hub neither hangs nor stands but utilises the whole wheel structure"?

That's a good attempt at a King Solomon solution but I am not budging by pandering to semantics. Your suggestion is a bit of both. It isn't.
If the tension in the top spokes don't change, we can safely say that the hub does not hang on them? Agreed?
If the tension in the bottom spokes reduce, we can safely start to think that the word stand is not all that alien.
I suggest anyone who really wants to understand this should first learn how modern concrete lintels work,

I'm not sure what you mean when you say that my "suggestion is a bit of both". My suggestion is that it's neither (hanging or standing), not a bit of both. Spookily your quote I've used includes the word "neither".
@Yellow Saddle agreed (his emboldening): "You are absolutely right in your description. You'll notice that I always use "stand" within quotations since there is no single word I can think of to to replace " So the hubs neither hangs nor stands but utilises the whole wheel structure and wouldn't work without all the elements of that structure."
I am not inviting you to "budge by pandering to semantics". You have used a normal word (stand) and misapplied it, because you think that "people find the concept [of other spokes' tension varying as well] difficult to digest as it is."
YS: "we can safely say that the hub does not hang on them? Agreed?" Yes, as I said "a loaded hub does not "hang" on the top spokes".
YS: "If the tension in the bottom spokes reduce, we can safely start to think that the word stand is not all that alien." You can "start to think" this if you like.
But in English "stand" (in the physics context) implies that the subject (in this case the hub) is being supported (ie experiencing a positive force) by the item being 'stood' on (in this case the bottom spoke). In a wheel under load this is NOT the case: the bottom spoke remains in (albeit reduced) tension and still 'pulls' (downwards) on the hub. So using the word "stand" in this context is "alien" (ie 'wrong') and your use of it like this is not "safe" ie it is liable to sew confusion (as we've seen above and in other threads).