Well not with my power input.
Bike Forum
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Chains do not stretch, discuss?
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Posted 3 years ago #
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it will stretch.
maybe elastically and maybe minutely but it will - it has to it's the law.
Posted 3 years ago # -
You get wear at the pins and inner plates. a thou of wear in each one results in a longer chain. See Sheldon Brown for details
Posted 3 years ago # -
Chains don't stretch. But the bushes around the pins wear, so a chain will get longer.
Posted 3 years ago # -
See above
Theres no significant plastic deformation along the length of the plates.
Posted 3 years ago # -
plastic deformation
Takes me back to T203 - Material Science
Posted 3 years ago # -
hmmm
now even a stretchy thing is purely it's 'bits' moving further apart, even at a molecular level. does the parts of a chain becoming further apart not have the same effect? does the true definition of 'stretch' imply an plastic deformation? does it require that the amount of material stay the same?
anyone clarify?
Posted 3 years ago # -
tie a chain to soemthing. Hang an anvil, or an Acme 16tonne weight off it. It'll stretch. Thread closed.
Posted 3 years ago # -
Chains don't stretch. But the bushes around the pins wear, so a chain will get longer
what part of "getting longer" is not stretching ?
Posted 3 years ago # -
SFB - I'm guessing he means the effective length between the rollers increases as they, and the pins they rotate on, wear.
They do also stretch though - I've measured to check (sad I know).... Only Sram ones though as they are pish.
They roller wear is the significant factor - hence well lubed chains don't "stretch"/wear as fast.
Posted 3 years ago # -
If your hair grows it hasn't stretched.
Posted 3 years ago # -
I hung two Sram chains up side by side the other day.
One has seen plenty of use...the other brand new.
And there was a good couple of mm difference.
I'll take a pic & post tonight...
Quite surprising.Might even get one of the outer plates from each on the CMM next week, just to check.
Its quiet at work at the moment.Oh, & Sram are in a different league to Shitmano Chains.
Posted 3 years ago # -
ah but that is by the addition of new material
we need a conclusive definition of what 'stretch' is here
Posted 3 years ago # -
I'm sure if your mighty power were kept up for long enough you would cause a little creep over time.
Posted 3 years ago # -
See - Sram
Posted 3 years ago # -
If your hair grows it hasn't stretched.
so what nutrients do I need to avoid having to buy new chains by cloning ?
Posted 3 years ago # -
Iron, plus small amounts of some other metals I guess
Posted 3 years ago # -
Stretch - to lengthen, widen, distend, or enlarge by tension: to stretch a rubber band.
This implies that when the tension is removed the object will return to somewhere near its previous length. As chain length increases due to wear between the component parts this doesn't happen.Posted 3 years ago # -
I'm sure if your mighty power were kept up for long enough you would cause a little creep over time.
'Tis true, if you push on a wall for long enough, it will fall down, eventually
Posted 3 years ago # -
not so sure. wot we need is a proper scientist to tell us. leather elbow patches a must
Posted 3 years ago # -
the pins are fixed in the outer plates, and free to pivot in the inner plates and rollers (the little washer bits inbetween the inner plates)
the holes in the inner plates become marginally ovalised over time.
measure a chain, from centre pin to centre pin.....
over 12 links (inner and an outer pair), it should measure 12 inches.
if the 12 inches measures centre of one pin, to the edge of the 24th pin, then its time for a new chain
Posted 3 years ago # -
if you push on a wall for long enough, it will fall down, eventually
or you will...
This implies that when the tension is removed the object will return to somewhere near its previous length.
but it's in the nature of bike chains always to be under tension!
In my view, arguing about the verb is beside the point - the chain DOES get longer, and will also be a poor fit to an unworn cassette.
Posted 3 years ago # -
'Stretching' implies that a single, continuous object/piece of something is getting longer while remaining whole, or it does to me anyway! With a chain, single pieces are actually getting smaller but the combination of those parts gets longer.
Posted 3 years ago # -
As is so often these case with such things, the hypothesis has not been expanded on enough to form a useful question.
Chains do not stretch.
Not ture. The do undergo elastic deformation.
Can we measure it? With the right kit, yes.
Do we care? No
Is it significant to wear and performance? No.Posted 3 years ago # -
The original post says "Not with my power output", missing the point- chains DO stretch but not because of the power applied, but because of wear and tear. Any stretching due to power loading is irrelevant.
Posted 3 years ago # -
Any stretching due to power loading is irrelevant.
except inasmuch as some of the 'larger gentlemen' riders I know seem to have an increased incidence of snapped chains...
Posted 3 years ago # -
chains do get longer but its unlikely that the link plates will stretch, or even if they do the wear in the pins will be more of an issue.
more to the point, who cares?
Posted 3 years ago # -
i like onzadogs alternative universe nice and simple
Posted 3 years ago # -
simonfbarnes - except inasmuch as some of the 'larger gentlemen' riders I know seem to have an increased incidence of snapped chains...
not because it has stretched, probably more because the pins or plates have deformed and ping loosePosted 3 years ago # -
I suspect they do deform (stretch) under load, but not noticably - and then they snap. If a link suffers damage, then a snap is more likely within "normal" pedalling-uphill loads.
I agree with the bushing wear resulting on permanent lengthening. I now understand why cleaning and lubing helps control wear rates.
Posted 3 years ago # -
the gaps between links get longer due to wearing on the cassette /chain ring get a chin wear tool and check if you done beleive me
Posted 3 years ago # -
mine just snap
too much torque of course Posted 3 years ago # -
'Tis true, if you push on a wall for long enough, it will fall down, eventually
Not if you're below the creep threshold, otherwise your mountains would have flattened out by now
OK lets sort/summarise this....
Chains do stretch elastically under ANY load, but return to normal length when unloaded.
Chain parts do not stretch plastically, permanent length changes are caused by wear at the inner plate/pin joint. So while the chain may change length over time the question of stretch becomes one of do we define stretch as a change of length of parts of the chain or a change of length of the item as a whole.
If you look on a half-link basis the chain does not stretch, if you look on a whole-link, or whole chain basis it does by way of wear.The word stretch does not require deformation to be due to plastic or elastic material deformation?
Posted 3 years ago # -
Chains do stretch elastically under ANY load
are you sure? - a quick calc would say would need to weigh just over 7 tonnes to exceed the yield strength of a single plate or am i missing something - and yes i know chains fail but again that is wear and deformation around the pin holes
Posted 3 years ago # -
are you sure? - a quick calc would say would need to weigh just over 7 tonnes to exceed the yield strength of a single plate or am i missing something - and yes i know chains fail but again that is wear and deformation around the pin holes
You're missing something :-), to exceed the yield strength would be going into plastic deformation, elastic deformation occurs below yield (thats the definition of the elastic limit/yield point). Its just that elastic deformation returns to original length when unloaded.
Posted 3 years ago #
Topic Closed
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