Ultegra & Dura Ace chains barely elongated after ~3500 miles (5600 km)

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alanyu
Posts: 1503
Joined: Thu Jun 06, 2019 1:10 pm

by alanyu

This is simply a wrong comparison. Metal is NOT plasticine, whose physics properties are a lot different. Plasticine seems larger due to it can be slightly less dense. In fact the volume doesn't change, but its surface area changes. In comparison, the roller can't be less dense, except corrosion or oxidation, which is another story.
Krzysio wrote:
Thu Mar 30, 2023 5:31 pm
Take a bit of plasticine, roll it and you'll se how worn roller can have larger diameter, than new one
Worn rollers do lose material, which has been well studied by CS, ZFC, Silca, etc, but not major.
Krzysio wrote:
Thu Mar 30, 2023 5:31 pm
Worn rollers will basicaly not lose material.
I agree, but here you are contradictory to the first point "larger diameter". Pressure on surface squeeze the metal or make a dent, etc. It doesn't make it larger. ZFC has a lot of pictures showing the deformation/dent. Objects prefer staying at its lowest potential energy, and in the driving system, the dent/deforming part of the roller has a lower potential during the dynamics, which makes the contact area smaller.
Krzysio wrote:
Thu Mar 30, 2023 5:31 pm
They get worn significantly by being rolled with presure
Agree, the worn pin elongates the chain.
Krzysio wrote:
Thu Mar 30, 2023 5:31 pm
Pins are abraded, and this, and only this elongates chain.
Links do elongate under optical microscopy, due to creep, but it contributes negligibly to elongation compared to wearing down of the pin.
Krzysio wrote:
Thu Mar 30, 2023 5:31 pm
Unless someone will report links elongation.

Krzysio
in the industry
Posts: 41
Joined: Thu Jul 11, 2019 8:45 am

by Krzysio

alanyu wrote:
Thu Mar 30, 2023 10:35 pm
This is simply a wrong comparison. Metal is NOT plasticine, whose physics properties are a lot different. Plasticine seems larger due to it can be slightly less dense. In fact the volume doesn't change, but its surface area changes. In comparison, the roller can't be less dense, except corrosion or oxidation, which is another story.

O.K. then - your roller is not plasticine while mine is... oh, of course it is not. But in fact it has the same properties, though on different scale. And problem is, you've got tendency to make negligible factors important, while denying not negligible. This one is not negligible, while weight loss is. At least for chain ( admit - very strange one, wchich I remember is "no", because you never met ) I presented here. But I'm not so keen to convine you by dismounting brand new DA chain to put it's rollers on the scale against mine. You can be correct for yourself and whoever else, no problem. So, if you look at the photos of new roller compared to mine, rolled to larger diameter between links and chainring, you'll see where material mostly gone, by craddling external surface, and on internal you can see central lip created between inner links by rolling process. Like plasticine. External diameter expanded by 0.25. Whatever negligible weight loss.
Maybe for me it's bit easier to understand how it works, because I'm bit formaly educated this way, plus sheet steel cold rolling process was invented by my compatriot by name of Sendzimir. I can't claim I must be trustworthy man to you. You can ask your local blacksmith then. If you can find any. Sorry, I went to far. But I hope you forgive me, as I'm old enough to remember one even next to my backyard, though it was a County Capital.
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Krzysio
in the industry
Posts: 41
Joined: Thu Jul 11, 2019 8:45 am

by Krzysio

Links do elongate under optical microscopy, due to creep, but it contributes negligibly to elongation compared to wearing down of the pin.
Krzysio wrote:
Thu Mar 30, 2023 5:31 pm
Unless someone will report links elongation.
[/quote]
Thank you for saying "negligibly". This was critical word for me, and I think it sorted our problem, so I can leave this forum till late autumn for real world cycling, as here, in my country season just begins. You gave me really unusual theoretical experience, maybe more useful for so-called "e-sport", which I personaly do not consider sport. I'll rather come back to riding this real DA chain, and see what fisically happens next.

alanyu
Posts: 1503
Joined: Thu Jun 06, 2019 1:10 pm

by alanyu

Krzysio wrote:
Fri Mar 31, 2023 3:11 pm
This is simply a wrong comparison. Metal is NOT plasticine, whose physics properties are a lot different. Plasticine seems larger due to it can be slightly less dense. In fact the volume doesn't change, but its surface area changes. In comparison, the roller can't be less dense, except corrosion or oxidation, which is another story.

O.K. then - your roller is not plasticine while mine is... oh, of course it is not. But in fact it has the same properties, though on different scale. And problem is, you've got tendency to make negligible factors important, while denying not negligible. This one is not negligible, while weight loss is. At least for chain ( admit - very strange one, wchich I remember is "no", because you never met ) I presented here. But I'm not so keen to convine you by dismounting brand new DA chain to put it's rollers on the scale against mine. You can be correct for yourself and whoever else, no problem. So, if you look at the photos of new roller compared to mine, rolled to larger diameter between links and chainring, you'll see where material mostly gone, by craddling external surface, and on internal you can see central lip created between inner links by rolling process. Like plasticine. External diameter expanded by 0.25. Whatever negligible weight loss.
Maybe for me it's bit easier to understand how it works, because I'm bit formaly educated this way, plus sheet steel cold rolling process was invented by my compatriot by name of Sendzimir. I can't claim I must be trustworthy man to you. You can ask your local blacksmith then. If you can find any. Sorry, I went to far. But I hope you forgive me, as I'm old enough to remember one even next to my backyard, though it was a County Capital.
:noidea:
8500 km CN-M9100: roller1 OD 0.755 mm, roller2 OD 0.750 mm
brand new CN-M9100 #1: roller1 OD 0.765 mm, roller2 OD 0.765mm
brand new CN-M9100 #2: roller1 OD 0.765 mm, roller2 OD 0.770mm

Maybe ask your workmates who are good in physics: "How does pressure/shock effect? Does it enlarge the metal along the direction of the force, or in the perdenticular direction of the force?"
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8500km roller1
8500km roller1
8500km roller2
8500km roller2
brand new #1 roller1
brand new #1 roller1
brand new #1 roller2
brand new #1 roller2
brand new #2 roller1
brand new #2 roller1
brand new #2 roller2
brand new #2 roller2

Krzysio
in the industry
Posts: 41
Joined: Thu Jul 11, 2019 8:45 am

by Krzysio

There is no one to be my workmate since I'm retired from work. Rollers worn by guy I took chain from are different than yours, and pins are different from any worn chain I've ever seen. As I explained I took this chain for all it's curiosities. As I said before - probably your chain is not plasticine while mine is.

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