stress relieving new wheels myths?

[andrew_s]

What's the recommended way to stress relieve a wheel.

The normal way is to put on gardening gloves, and go round the wheel squeezing pairs of spokes as hard as you reasonably can. I put an old steerer tube in the outer cross, and push towards the hub.

[Freddie]

He didn't say they were tensioned that much, he was posing a hypothetical situation by way of comparison.

It's a red herring.
Keep the example to the real world: at 200kg the rim, whether has eyelets or not, will break.
Such figure has nothing to do with the "stress relieving", as far as I can see from the OP?

With respect, am I correct in saying English is not your first language, as I think you have missed the nuance in Brucey's post.

[531colin]

........... Brandt's article tells you what not to do rather than what to do.

From the article........
".............. However, stretching spoke pairs with a strong grasp at mid-span, can momentarily increased tension by 50% to 100%. Because spokes are usually tensioned no higher than 1/3 their yield stress, this operation has no effect on the spoke as a whole, affecting only the small high stress zones where spokes are near yield....."

Because I'm familiar with the technique, I didn't trip over the "stretching....with a strong grasp" bit....Easier for a UK English audience to understand "squeezing"....etc....?

[mercalia]

is the metallurgical reason to do it really a myth?

Can you explain why you think it is a myth?

well I also a member of a hifi forum and that hobby and interest full of dubious ideas & advocates, that seem plausible. from fancy mains cables to directional audio cables & magic boxes full of ***** that you put on top of your cd player, little devices that you use to "warm" up your phono cartridge, a long list. I cant see that cycle forums should be anything different. And the spoke thing seems a likely candidate as it generates technospeak to bamboozle the faithful

[Gattonero]

It's a red herring.

It absolutely isn't.

My point is that if you leave your wheel un-stress-relieved, the peak stresses in the spokes are locally much higher than any average you could ever achieve in reality, and they are very likely to break as a consequence.

Brandt's book describes a safe and effective method of stress relief, which involves grasping and squeezing (hard) groups of spoke crossings. The only really bad thing about this method is that it makes your hands sore, so wear gloves.

cheers

Then is just a misunderstanding.
I don't get where the 200kg come from and what they have to do with stress-relieving of a wheel?

If you're talking about the "peak stress" then it's more realistic, and as I said: a wheel that is well build does need stress-relieve mainly to make sure that spoke heads&nipples are seating correctly and to confirm that spoke tension is even with no "peaks".

Perhaps we're saying the same thing in different ways?

[Gattonero]

He didn't say they were tensioned that much, he was posing a hypothetical situation by way of comparison.

It's a red herring.
Keep the example to the real world: at 200kg the rim, whether has eyelets or not, will break.
Such figure has nothing to do with the "stress relieving", as far as I can see from the OP?

With respect, am I correct in saying English is not your first language, as I think you have missed the nuance in Brucey's post.

Thus creating a myth?

[Brucey]

... well I also a member of a hifi forum and that hobby and interest full of dubious ideas & advocates, that seem plausible. from fancy mains cables to directional audio cables & magic boxes full of ***** that you put on top of your cd player, little devices that you use to "warm" up your phono cartridge, a long list. I cant see that cycle forums should be anything different...

well what we are talking about is just engineering and materials science here, not untestable hypotheses, fairy stories or wishful thinking as found in the crazy world of 'hi fi'... (BTW you'd be amazed how many of those blighters are practically tone deaf..... )

I -like many other folk I expect- do have some beliefs about bicycles which are not easy to substantiate, but when I mention these I try to make it clear that this is what they are, rather than matters of fact.

Wheel stress relief is well understood, is known to work in practice, and is pretty well substantiated. I don't think you ought to put into the same category as 'audiophile guff'....

cheers

[Freddie]

Brucey, a quick question, do similar points of high stress exist in suspension bridges, if so, how are they dealt with.

[CREPELLO]

is the metallurgical reason to do it really a myth?

Can you explain why you think it is a myth?

well I also a member of a hifi forum and that hobby and interest full of dubious ideas & advocates, that seem plausible. from fancy mains cables to directional audio cables & magic boxes full of ***** that you put on top of your cd player, little devices that you use to "warm" up your phono cartridge, a long list. I cant see that cycle forums should be anything different. And the spoke thing seems a likely candidate as it generates technospeak to bamboozle the faithful

Now I really enjoy a good hifi sound, but as I spend most of my spare money on bikes (although I have acrued a large cd/lp collection), I have never really persued the art of the ultimate hifi. One reason is that it seems a much more expensive hobby than cycling, but I am strongly aware of the esoteric nature of listening to an comparing hifi equipment. Ignorance is bliss and I prefer by and large, to enjoy the music without the limitations of the hardware getting in the way.

I think the art and understanding of wheel building is a bit more objective than understanding good hifi sound (or perhaps I mean less complicated ). A better comparison in cycling would be pursuit of the best frame materials and designs. As many on this forum have attested, they find differences between many materials marginal at best and yet there will be those who passionately believe the differences are substantial and objective.

With regard to wheel building and stress relieve, it's clear to me that spokes that have not been properly formed into the build will be in a constant state of static stress. Manipulate the spokes into their natural line within the build and everything locks into place with the result that the spokes are not stressed to unnatural positions and the desired spoke tension will stay there, spread evenly between all the spokes.

My understanding is somewhat limited, but wheel building me is partly an art, one of gut feeling and what feels right, backed up by a learnt understanding - much of it from this forum

[kylecycler]

What's the recommended way to stress relieve a wheel.

The normal way is to put on gardening gloves, and go round the wheel squeezing pairs of spokes as hard as you reasonably can. I put an old steerer tube in the outer cross, and push towards the hub.

I suppose if you wanted to be really flash, you'd treat yourself to a pair of these, for the 'professional look'...
https://www.aldi.co.uk/p/92479/0
There are still plenty in my local Aldi; they might even get reduced soon. Maybe a bit too good and even too expensive for the purpose (unusually for Aldi), but they look ideal. I was looking at them and thinking I'd really like a pair but couldn't think what I'd use them for! It might waste them, though.

In Sheldon's article on wheel building, John Allen uses an old left crank to do what you do with an old steerer tube:


http://www.sheldonbrown.com/wheelbuild.html

I didn't really understand stress relieving - I knew you were supposed to, I just didn't know why. Still find it hard to get my head round, but the explanations in this thread have helped.

[cycleruk]

In Sheldon's article on wheel building, John Allen uses an old left crank to do what you do with an old steerer tube:


http://www.sheldonbrown.com/wheelbuild.html

I didn't really understand stress relieving - I knew you were supposed to, I just didn't know why. Still find it hard to get my head round, but the explanations in this thread have helped.

When Jobst says grab two spokes - is that the 2 spokes he means or another 2 and is that one way to do it ?
P.S. That's the way I do it.

[Brucey]

Brucey, a quick question, do similar points of high stress exist in suspension bridges, if so, how are they dealt with.

it depends how the bridge is made.... a 'safe' way of doing it is to bolt/attach parts together such that each part doesn't have inbuilt stresses, and such that the bolting (or other joining) operation doesn't itself introduce additional harmful stresses.

In many cases (eg welded) large structures cannot be fabricated without there being high levels of residual stress in them, as well as various geometric stress concentrators. In some cases both appear at once. In these cases there are various methods of dealing with this, eg.

- in situ stress-relief heat treatment
- vibrationary stress-relief treatment
- weld dressing
- local mechanical treatment (eg shot peening of weld beads)
- proof loading tests
- validated design
- coded design
-periodic inspection

Coded/validated designs are made according to standards that are justified using years (sometimes decades) of research work and practical experience. Something like a suspension bridge is arguably easier than some other things in a way; unlike a bicycle wheel it doesn't need to (or could) have an infinite fatigue life, and periodic inspections should detect cracks etc before they get to the kind of size where they might result in failure of the whole structure.

The closest thing to 'stress relief in wheels' is probably something like a proof-loading test (eg in a pressure vessel); if parts of the structure go to yield during the proof loading (in a controlled fashion) this can improve the service life in a similar way.

cheers

[MikeF]

In Sheldon's article on wheel building, John Allen uses an old left crank to do what you do with an old steerer tube:



I didn't really understand stress relieving - I knew you were supposed to, I just didn't know why. Still find it hard to get my head round, but the explanations in this thread have helped.

When Jobst says grab two spokes - is that the 2 spokes he means or another 2 and is that one way to do it ?
P.S. That's the way I do it.

I thought it was pairs of parallel spokes, not two crossing spokes or perhaps it doesn't matter which? I'm sure someone more expert will enlighten us.

Also if you re-rim a wheel do you need to stress relieve again? I would have thought the initial build and riding should have done most of the stress relieving, but presumably the rebuild might have added some stress.

[531colin]

............ as I said: a wheel that is well build does need stress-relieve mainly to make sure that spoke heads&nipples are seating correctly and to confirm that spoke tension is even with no "peaks"..............

No. Spokes need stress-relieving, to relieve the stresses built up in the steel by all the processes the spokes go through.....from drawing the wire through forming the head and rolling the thread all the way to building and tensioning the wheel.
Without stress-relieving, the fatigue life of the spoke is shortened due to the built-in stress in the metal.

[531colin]

I have always squeezed the (near) parallel pairs of spokes.....both sides of the wheel at the same point, at the same time.
I don't see why you wouldn't stress-relieve a wheel you were re-rimming....its free, and it can't be a bad thing.