Spoke fatigue & wheel rebuilding

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531colin
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Re: Wheel rebuild - should I replace the spokes?

Post by 531colin »

Brucey wrote:.....ah, yes, you are quite right, but this means you might still get an 'underbend' which is just as bad, for similar reasons....


Absolutely, Brandt's parallel pair squeeze does nothing for the nipple end bend.

Just so I'm clear, do you get the last crossing on the left and right side of the wheel and squeeze them together?
That seems like a good scheme to me, because it works for the nipple end as well, and if you use the heel of your hand it shouldn't produce arthritis.
Long ago, you were teasing us about a stress-relieving device you were considering......did it get anywhere?
Brucey
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Re: Wheel rebuild - should I replace the spokes?

Post by Brucey »

531colin wrote:Just so I'm clear, do you get the last crossing on the left and right side of the wheel and squeeze them together?
That seems like a good scheme to me, because it works for the nipple end as well, and if you use the heel of your hand it shouldn't produce arthritis.


yes, yes, and maybe respectively. I usually interlock my fingers so that I can squeeze better, but it still knocks the wotsits out of my hands, hence 'the machine'...

Long ago, you were teasing us about a stress-relieving device you were considering......did it get anywhere?


yes, but it was not an unqualified success if I'm honest. On the plus side I can easily apply enough tension to do the business even with 13G spokes. On the minus side...

a) it is a bit slower to use (if I build another one it'll be a different design and much better in this respect) and

b) the parts that bear against the spokes (thus far with 14G or fatter spokes) have nearly always put a set into them.

Now b) was a disappointment; regardless of the radius I used on the tool, I always got a 'set' in the spoke, even working well away from the crossing. In hindsight this may be a reflection of the tension introduced; if the spoke is close to yield in tension, it will take a set in bending somewhat more easily.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
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NATURAL ANKLING
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Re: Wheel rebuild - should I replace the spokes?

Post by NATURAL ANKLING »

531colin wrote:
NATURAL ANKLING wrote:.........
If spokes aren't tensioned some what before stress relieving ............:


"stress relieving" ......doesn't this mean making sure that the spokes are bent to the exact angle(s) required in the finished wheel? ie. they are not flexed to achieve that angle? (the flex is the "stress" in the metal that needs to be relieved)
So the wheel needs to be "finished" ie (tight, even, true, round, dished.......) before it can be stress relieved?.....and the stress is relieved by momentarily taking the tension well above that which will be seen in service?
This is one area where I went away from Brandt.....if memory serves, Brandt stress-relieved when spokes were below final tension......I used to do it at final tension.


I was saying that if you hardly tension the spokes and then stress relive with an object then there is a good chance of adding another bend which if on shank (Straight part of spoke) will never be removed, even if stress relieving at full tension.
Also if you attempt to bend metal cold, and its not held tight or clamped then you end up with bends all over the place.

I just been working on a wheel tonight (still am) and have stress relived after trueing and centring (near final tension) then true and centre again, stress relieve at final tension and true till no more run out is seen after last stress relief :?:

I have read this somewhere that when stress relieving yields no run out you are done :?:
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope
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NATURAL ANKLING
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Re: Wheel rebuild - should I replace the spokes?

Post by NATURAL ANKLING »

Hi,
Bit about nipple end of spoke is interesting.
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
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531colin
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Re: Wheel rebuild - should I replace the spokes?

Post by 531colin »

I only do a proper stress-relief once per wheel......my hands won't stand any more.
My finishing off involves placing the axle end on the floor, hands at 9 and 3 o'clock on the rim, and pushing down with a fair bit of my body weight all round the rim by rotating the wheel, turn over and repeat......you get all sorts of satisfying pinging noises as the spokes unwind.....some call this "stress-relieving", but to me it doesn't load individual spokes enough, I call it "stressing the wheel"....with a light rim and a dished wheel, you can feel the difference in rigidity one side vs. the other.
My final repeating cycle is...."stress the wheel, true the wheel, balance the tension".....repeat, until stressing the wheel doesn't cause it to go out of true.
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531colin
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Re: Wheel rebuild - should I replace the spokes?

Post by 531colin »

Brucey wrote:
531colin wrote:Just so I'm clear, do you get the last crossing on the left and right side of the wheel and squeeze them together?
That seems like a good scheme to me, because it works for the nipple end as well, and if you use the heel of your hand it shouldn't produce arthritis.


yes, yes, and maybe respectively. I usually interlock my fingers so that I can squeeze better, but it still knocks the wotsits out of my hands, hence 'the machine'...

Long ago, you were teasing us about a stress-relieving device you were considering......did it get anywhere?


yes, but it was not an unqualified success if I'm honest. On the plus side I can easily apply enough tension to do the business even with 13G spokes. On the minus side...

a) it is a bit slower to use (if I build another one it'll be a different design and much better in this respect) and

b) the parts that bear against the spokes (thus far with 14G or fatter spokes) have nearly always put a set into them.

Now b) was a disappointment; regardless of the radius I used on the tool, I always got a 'set' in the spoke, even working well away from the crossing. In hindsight this may be a reflection of the tension introduced; if the spoke is close to yield in tension, it will take a set in bending somewhat more easily.

cheers


I might just get something like this from Screwfix, clamp it in the vise** and press each spoke crossing on it, holding the rim at 3 and 9 o'clock......
**without the swivel, obviously

Image

http://www.screwfix.com/p/select-swivel-castor-150mm/4029p#product_additional_details_container
Brucey
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Re: Wheel rebuild - should I replace the spokes?

Post by Brucey »

that is certainly worth a go, (and maybe there is a way of dong this that I have not thought about yet), but I wouldn't be surprised if you end up with some kinks in the spokes ( especially at the crossing).

I suspect the PU tyre on that wheel is about the right consistency (maybe it could be thicker?) but for whatever reason (maybe it is the shape?, maybe it is the tension?) my hands don't seem to kink the spokes but the tools I have tried do so much more easily.

I think that a wider tool that works pairs of spokes just above the crossing (so that the crossing itself doesn't kink, which looks terrible and is difficult to correct) might be the way to go?

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
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tykeboy2003
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Re: Wheel rebuild - should I replace the spokes?

Post by tykeboy2003 »

In reply to the OP.

Conventional wisdom is yes, buy new spokes, however, a few years ago my rear wheel was buckled beyond repair so I bought a new rim and simply rebuilt the wheel (rear) with the hub and original spokes. Never had a problem with it.
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531colin
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Re: Wheel rebuild - should I replace the spokes?

Post by 531colin »

I think the wheel is actually 6" x 2".
I have one on "click and collect", so I will know soon.....maybe i should have splashed out on two of them? :wink:
(damned sight cheaper than new hands!)
Keezx
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Re: Wheel rebuild - should I replace the spokes?

Post by Keezx »

531colin wrote:I only do a proper stress-relief once per wheel......my hands won't stand any more.
My finishing off involves placing the axle end on the floor, hands at 9 and 3 o'clock on the rim, and pushing down with a fair bit of my body weight all round the rim by rotating the wheel, turn over and repeat......you get all sorts of satisfying pinging noises as the spokes unwind.....some call this "stress-relieving", but to me it doesn't load individual spokes enough, I call it "stressing the wheel"....with a light rim and a dished wheel, you can feel the difference in rigidity one side vs. the other.
My final repeating cycle is...."stress the wheel, true the wheel, balance the tension".....repeat, until stressing the wheel doesn't cause it to go out of true.


That's certainly not "stress relief" like Jobst Brand it ment to be, but it has always worked for me.
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531colin
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Re: Wheel rebuild - should I replace the spokes?

Post by 531colin »

This is looking like it might work.........

Image

Thats the big caster wheel from Screwfix gripped in a "workmate" at saw-horse height to make it easy to get a bit of a lean down onto it.
There are bits of wood either side of the caster to act as guides so I don't get the spokes off the side. The bike wheel is a 26", 36 spoke, 3 cross, if it matters.
With the 2" wide caster there is room for me to stress the spokes away from the third crossing, so i shouldn't kink the spokes at the crossing?
Hmmmmm.....looks like I should build myself a pair of wheels?
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Gattonero
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Re: Wheel rebuild - should I replace the spokes?

Post by Gattonero »

Robin78 wrote:Hi,

I am replacing both the rims on the wheels on my Specialized Sirrus hybrid bike. The bike is about six years old and the current rims are wearing thin from contact with the brake pads. My plan was to take each old wheel off the bike. tape the new rim to the old one and simply transfer the spokes one by one. However, I have found one of the spokes to be broken (on the back wheel) and now I am wondering if I should also replace all the spokes too. So what I want to know is whether spokes are parts that need to be replaced after a good period of use, or whether they 'go on forever' and I could get away with simply replacing the broken one(s).

Thank you in advance :)

Robin


Off-the shelf mid-priced bikes would almost always have "no brand" spokes. After 6 years they may well be fatigued, in fact one spoke broke already.
Add to this that the spokes would get mis-shaped while laced and tensioned, if you were to remove them you will notice that they get a different bend according to their position (i.e. the rear trailing Lh is different from the rear trailing Rh). One more reason to not reuse them, unless you have time to lear and are ok with keep on replacing them when they will break.
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...
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NATURAL ANKLING
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Re: Wheel rebuild - should I replace the spokes?

Post by NATURAL ANKLING »

Hi,
Cable tie crosses, remove nipples leave spokes in hub, transplant rim.
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
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Gattonero
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Re: Wheel rebuild - should I replace the spokes?

Post by Gattonero »

NATURAL ANKLING wrote:Hi,
Cable tie crosses, remove nipples leave spokes in hub, transplant rim.


If (if) the spokes are good, don't need to tie down the crosses. Just tape the new rim onto one side (the Rh for the rear wheel) and align the spoke holes, paying attention to their orientation and the rim label too.
Then just move the spokes one by one from one rim to another, in sequence just as they come on the rim. New nipples are often a good idea.
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...
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NATURAL ANKLING
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Re: Wheel rebuild - should I replace the spokes?

Post by NATURAL ANKLING »

Hi,
Which way could you do quicker :?:
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
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