Chains do not stretch, discuss?

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  • Chains do not stretch, discuss?
  • and remain shorter in terms of length.

    what other terms might they have been shorter in ?

    Olly
    Member

    plastic deformation only stops when the object is cooled to absolute zero (-270somethingish)
    solids are only truly solid at absolute zero.
    the same idea applies to glass in windowpanes, whereby glass over 100 years old or so, is noticebly thicker at the botttom than the top, due to flowing down the pane and sagging.

    ive snapped chains, and im a portly 11st.
    i THINK its more to do with application of load, rather than the load itself, ive only done it whileplaying silly buggers on toy bikes
    i think it also only occours where ive done something silly with the pin, like pushed in a normal pin to join a chain, causing a weakness on ones side, allowing the outer plate to be forced to pop off the roller due to slight side forces incurred while the chain is crossed from middle ring to big sprocket.

    slight side loads (due to gear selection) + dodgey bodge in a pin + Torque = crotch + stem + “Ow!”

    mudshark
    Member

    …glass in windowpanes, whereby glass over 100 years old or so, is noticebly thicker at the botttom than the top, due to flowing down the pane and sagging…

    That’s true – we rotate ours every 50 years.

    So if I’ve read it right

    Pitch length increases as the pins and bushes wear.

    The side plates are unlikely to be plastically deformed due to creep at standard riding temperatures.

    solids are only truly solid at absolute zero.

    no, at that temperature they just stop molecular vibration

    the same idea applies to glass in windowpanes, whereby glass over 100 years old or so, is noticebly thicker at the botttom than the top, due to flowing down the pane and sagging.

    apocryphal. In fact, older glass panes are thicker at the bottom (if at all) due to the casting methods used. Modern glass is cast floating on liquid metal and highly uniform.

    Premier Icon hot_fiat
    Subscriber

    the same idea applies to glass in windowpanes, whereby glass over 100 years old or so, is noticebly thicker at the botttom than the top, due to flowing down the pane and sagging.

    This is complete tosh of the finest urban myth sort. Yes glass is not a true crystalline material, being a supercooled liquid, and will “flow” over a (very considerable) amount of time, but not in your, mine or anybody else’s lifetime.

    Pre tin float glass, panes were made from bullseye glass that was spun out into a disk from a blown glass bubble. The disks were then cooled and cut up into panes. As they were formed from a disk created under centrifical force, they were thicker at one end than the other. In order to make glazing easier, glaziers would place the thicker portion at the bottom of the pane and so joe public naturally thinks that the glass has flowed from the top of the pane to the bottom. The cheapest panes were those from the centre of the bubble where the bowing iron or puntee were attached. These would be really thick and have a round glass bullseye in them.

    Premier Icon glenh
    Subscriber

    Good one for QI that. Are you listening Stephen?

    coffeeking
    Member

    ballsofcottonwool – as someone said above, chains almost always snap due to pin/plate joint failure, slight misalignment or lateral forces, or material failure if the chain fatigues in the middle of the plate (rare). Technically you should never find a bike chain that has snapped due to a plate failing in plain tension.

    As hot_fiat says, glass creep takes immense amounts of time, longer than a window would remain a window.

    Olly
    Member

    how is placeing a window pane with one theoretically minutley thicker end at the bottom, any easier than placing it any other way up??
    molecular vibration only stops completly at absoloute zero

    i stick to my guns, but cant be bothered to argue it :p

    ball of cotton wool has it 🙂

    I am also interested in how “larger gentlemen” break chains. I doubt they put more load thru them that we do on the tandem. 22+ stone of us jumping on the pedals in 22 / 34 granny puts frightening loads on the chain – a load of nearly a tonne along the chain. ( and 4 tonnes on the pawls in the freehub) We break freehubs but not chains. At that level its not a function of fitness but of power and leverage – and with both of us putting all our weight on the pedals few solo riders will be able to match that.

    IMO chains break either when they are badly worn or when you make a mess of a gear change

    IMO chains break either when they are badly worn or when you make a mess of a gear change

    perhaps the fatties are just daydreaming about pies and stuff when they should be concentrating on clean gear changes ?

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