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  1. #51
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    Quote Originally Posted by Kontact View Post
    All normal springs go up in tension as they are compressed.
    This may be true, but what is the % of movement of the spring/full movement.

    The OP was questioning if you can stretch the chain dependent on the gear. You may be able to get the chain to stretch a little, if you hang your car off of it. But there is no way the derailuer has any where enough force to stretch a steel chain. period!.
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  2. #52
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    Quote Originally Posted by duriel View Post
    This may be true, but what is the % of movement of the spring/full movement.

    The OP was questioning if you can stretch the chain dependent on the gear. You may be able to get the chain to stretch a little, if you hang your car off of it. But there is no way the derailuer has any where enough force to stretch a steel chain. period!.
    Thank you for telling me what I already said:

    Since it is running through a spring powered idler, it does have more tension in some combinations.

    Just not enough to matter.
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  3. #53
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    Quote Originally Posted by cxwrench View Post
    And yes...unless the derailleur pivot spring is a rising rate spring why would the tension change?
    Because even a linear spring rate (which most coil springs are) exerts more force the more it is compressed or elongated.

    I think you may be a little confused as to what "spring rate" means and how it works.

    You might want to test this before you answer...I've checked it before and there is virtually no change in the spring tension based on cage position. At least on non-clutch Shimano derailleurs.
    It is pretty obvious just grabbing and turning the derailleur cage that there is an increase in the tension as you turn it from fully retracted to fully extended. I am a bit puzzled how you do not feel it.

    But this is all a bit beside the point because nobody is suggesting that the difference in tension is enough to make a difference in checking the chain.

  4. #54
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    The solution is to replace your chain (and bike) every 5000 miles.....PS. Those chain checkers are good for letting you know when to check your chain with a good steel rule.
    If your opinion differs from mine, ..........Too bad.
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  5. #55
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    Quote Originally Posted by Kontact View Post
    All normal springs go up in tension as they are compressed. Normal springs increase tension linearly with a given amount of movement, and progressive springs do so in curve.
    Don't derailleur springs stretch rather than compress?
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

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  6. #56
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    Quote Originally Posted by Kontact View Post
    Hey Mr. Aggression, I'm not ignorant - I'm very aware of the angular wear issues that rollers create, which is why I created this diagram years ago:



    Anyone can post something on the internet reflecting their belief about how chains wear, regardless of whether they design chains or just work at a bike shop. You can look at the geometry I've posted and argue with that.
    I find it odd that you created and posted that very excellent diagram..... but then seem to contradict what it is pointing out.

    If I am understanding that correctly, it accurately shows what happens when the distance between rollers increases.

    However, that increase in distance between rollers occurs because of wear in the pivots (where the pins go through the side plates). Extra play in the rollers is not going to cause that distance to increase, and would not cause the wear shown in that diagram on its own.

  7. #57
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    Park tool chain wear gauge question

    Quote Originally Posted by Lombard View Post
    Don't derailleur springs stretch rather than compress?
    Yes, that is correct, but the same thing applies. When talking about springs, “compress” and “stretch” are both just different forms of the metal spring deflecting.

  8. #58
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    Quote Originally Posted by kapusta View Post
    I find it odd that you created and posted that very excellent diagram..... but then seem to contradict what it is pointing out.

    If I am understanding that correctly, it accurately shows what happens when the distance between rollers increases.

    However, that increase in distance between rollers occurs because of wear in the pivots (where the pins go through the side plates). Extra play in the rollers is not going to cause that distance to increase, and would not cause the wear shown in that diagram on its own.
    The diagram shows roller wear only - the green pivots remain at "new" distance from each other. The only thing that has changed is size of the hole in the rollers.

    This was originally in response to claims that roller wear doesn't change chain pitch. It won't - in a straight line. But when you wrap a chain around a cog roller wear will change the curved pitch of the chain, making it effectively longer by allowing the rollers to orbit higher.

    I should have posted a basic explanation about what is different between the two pictures.
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  9. #59
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    Quote Originally Posted by Lombard View Post
    Don't derailleur springs stretch rather than compress?
    No, I'm pretty sure all knuckle springs compress (AKA the A tension spring). Stretching a coil by untwisting it usually causes binding, so most coils that are used in a twisting direction are compressed into a tighter spiral under force.

    Where you thinking of the parallelogram spring Shimano switched to that stretches like a screen door spring?
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  10. #60
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    Quote Originally Posted by Kontact View Post
    No, I'm pretty sure all knuckle springs compress (AKA the A tension spring). Stretching a coil by untwisting it usually causes binding, so most coils that are used in a twisting direction are compressed into a tighter spiral under force.

    Where you thinking of the parallelogram spring Shimano switched to that stretches like a screen door spring?
    Oh, duh yeah! Brain fart on me. Nevermind!
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

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  11. #61
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    Quote Originally Posted by Kontact View Post
    The diagram shows roller wear only - the green pivots remain at "new" distance from each other. The only thing that has changed is size of the hole in the rollers.

    This was originally in response to claims that roller wear doesn't change chain pitch. It won't - in a straight line. But when you wrap a chain around a cog roller wear will change the curved pitch of the chain, making it effectively longer by allowing the rollers to orbit higher.

    I should have posted a basic explanation about what is different between the two pictures.
    If what you are trying to show is roller wear only, then your diagram is incorrect.

    In your diagram, the distance between all the worn rollers is greater (except when on the cog) than the unworn rollers. That is incorrect. Worn rollers alone will not cause that to happen.

    It is true that the play in the worn rollers can make any two of them farther apart when pushed (such as when you use the chain check tool we are debating), but all you are doing is pushing the rollers closer to the ones on either side of where you are checking.

    Worn rollers do not make the average distance between all the rollers greater. That is what is off in your diagram if what you are trying to show is worn rollers.

  12. #62
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    Quote Originally Posted by Kontact View Post
    No, I'm pretty sure all knuckle springs compress (AKA the A tension spring). Stretching a coil by untwisting it usually causes binding, so most coils that are used in a twisting direction are compressed into a tighter spiral under force.

    Where you thinking of the parallelogram spring Shimano switched to that stretches like a screen door spring?
    Oops, I was thinking of the parallelogram spring as well.

  13. #63
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    Quote Originally Posted by kapusta View Post
    If what you are trying to show is roller wear only, then your diagram is incorrect.

    In your diagram, the distance between all the worn rollers is greater (except when on the cog) than the unworn rollers. That is incorrect. Worn rollers alone will not cause that to happen.

    It is true that the play in the worn rollers can make any two of them farther apart when pushed (such as when you use the chain check tool we are debating), but all you are doing is pushing the rollers closer to the ones on either side of where you are checking.

    Worn rollers do not make the average distance between all the rollers greater. That is what is off in your diagram if what you are trying to show is worn rollers.
    I don't see your objection. The diagram shows pins at fixed distances from each other. The pins are being pulled into the minimum circumference possible because of chain tension. The rollers, having too-large holes in their centers, fail to locate the pins in the centers of the cog troughs, so the link pins descend further into those troughs, effectively reducing the chain wrap because of the reduced circumference. The result is that there isn't enough room left for the outer diameter of the rollers, and so they interfere with the cog teeth, as shown.


    This diagram has been posted here and other places for at least three years, and no one has suggested it is not geometrically accurate. Whether you think rollers should act like this or not, the diagram is not a trick - the green pins are at the same fixed distance from each other in both illustrations. So I'd suggest first thinking about what is depicted before you say what happens in real life.


    If the rollers are in the "wrong place", what mechanism would force them to be in what you think is the right place?
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  14. #64
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    Quote Originally Posted by Kontact View Post
    I don't see your objection. The diagram shows pins at fixed distances from each other. The pins are being pulled into the minimum circumference possible because of chain tension. The rollers, having too-large holes in their centers, fail to locate the pins in the centers of the cog troughs, so the link pins descend further into those troughs, effectively reducing the chain wrap because of the reduced circumference. The result is that there isn't enough room left for the outer diameter of the rollers, and so they interfere with the cog teeth, as shown.


    This diagram has been posted here and other places for at least three years, and no one has suggested it is not geometrically accurate. Whether you think rollers should act like this or not, the diagram is not a trick - the green pins are at the same fixed distance from each other in both illustrations. So I'd suggest first thinking about what is depicted before you say what happens in real life.


    If the rollers are in the "wrong place", what mechanism would force them to be in what you think is the right place?
    I did not say the diagram was inaccurate. In fact, I said exactly the opposite.

    What I AM saying is that it does not support what you are claiming.

  15. #65
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    Quote Originally Posted by kapusta View Post
    I did not say the diagram was inaccurate. In fact, I said exactly the opposite.

    What I AM saying is that it does not support what you are claiming.
    Then you must not understand what I'm claiming, because I'm claiming what the diagram shows.

  16. #66
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    Quote Originally Posted by Kontact View Post
    Then you must not understand what I'm claiming, because I'm claiming what the diagram shows.
    You have repeatedly claimed that measuring chain elongation - the cumulative effect of an increased distance between the pins - which is what a ruler measures - is irrelevant. I think your words were something like "as useful as measuring the box the chain comes in".

    Yet, in the diagram in question that you use to explain chain wear, the distance between the pins is GREATER on the worn chain (which is what chain elongation is). I am a little puzzled why you say the distance is not greater. It is plain as day looking at it, and I even put a ruler up to the diagram, and indeed the distance between the green pins IS greater on the worn chain compared to the new chain. THAT is why I said your diagram is accurate, because you show the distance increasing between the new and worn chain.

    (Just to be clear, I am talking about the distance between the pins that are NOT on the cog)

    Furthermore, your diagram shows why the cogs wear on the leading edge: because the extra distance between the pins as the chain leaves the cog causes the roller leaving the cog up top to hang up on the tooth. THAT is why the roller leaving the top of the cog is pressed up against the side of the tooth.

    From your explanation, I think I get what you are intending to show with that diagram, and I am not ruling out that you may have a point, and that roller wear may have SOME impact on cog wear. The problem is that by introducing chain elongation (which you are claiming is irrelevant) into the diagram, you end up giving a far more likely explanation than roller wear for the cog wear.

    If I can use an analogy, It would be like claiming that low tire pressure, rather than a bad alignment, causes a certain type of tire wear. But then to prove it, you use an example of a car with both low tire pressure AND a bad alignment.

    If you want a diagram to show how roller wear, and NOT chain elongation, causes cog wear, then use a diagram that does not include chain elongation.
    Last edited by kapusta; 01-01-2018 at 01:00 PM.

  17. #67
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    This thread reminds me of the sort of "verbal masturbation" I used to observe between some of my more obsessive classmates when I was an mechanical engineering student.....
    "L'enfer, c'est les autres"

  18. #68
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    Quote Originally Posted by No Time Toulouse View Post
    This thread reminds me of the sort of "verbal masturbation" I used to observe between some of my more obsessive classmates when I was an mechanical engineering student.....
    You hit the nail on the head here. But it could be worse. Can you imagine if 11spd came in here also?
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  19. #69
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    Quote Originally Posted by kapusta View Post
    You have repeatedly claimed that measuring chain elongation - the cumulative effect of an increased distance between the pins - which is what a ruler measures - is irrelevant. I think your words were something like "as useful as measuring the box the chain comes in".

    Yet, in the diagram in question that you use to explain chain wear, the distance between the pins is GREATER on the worn chain (which is what chain elongation is). I am a little puzzled why you say the distance is not greater. It is plain as day looking at it, and I even put a ruler up to the diagram, and indeed the distance between the green pins IS greater on the worn chain compared to the new chain. THAT is why I said your diagram is accurate, because you show the distance increasing between the new and worn chain.

    (Just to be clear, I am talking about the distance between the pins that are NOT on the cog)

    Furthermore, your diagram shows why the cogs wear on the leading edge: because the extra distance between the pins as the chain leaves the cog causes the roller leaving the cog up top to hang up on the tooth. THAT is why the roller leaving the top of the cog is pressed up against the side of the tooth.

    From your explanation, I think I get what you are intending to show with that diagram, and I am not ruling out that you may have a point, and that roller wear may have SOME impact on cog wear. The problem is that by introducing chain elongation (which you are claiming is irrelevant) into the diagram, you end up giving a far more likely explanation than roller wear for the cog wear.

    If I can use an analogy, It would be like claiming that low tire pressure, rather than a bad alignment, causes a certain type of tire wear. But then to prove it, you use an example of a car with both low tire pressure AND a bad alignment.

    If you want a diagram to show how roller wear, and NOT chain elongation, causes cog wear, then use a diagram that does not include chain elongation.
    You're puzzled because you repeatedly have misunderstood the diagram, even with my explanation.

    The diagram shows two chains with exactly the same pin and link dimensions. Zero elongation. I made the diagram, I measured the distance between pins with a caliper. Zero.

    The diagram only shows what happens when the inside of the rollers are worn. That's all.
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  20. #70
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    Quote Originally Posted by No Time Toulouse View Post
    This thread reminds me of the sort of "verbal masturbation" I used to observe between some of my more obsessive classmates when I was an mechanical engineering student.....
    That's funny. Your posts remind me of a troll, who alternates between personal potshots at people discussing technical bike stuff on, of all places, the mechanical section of a bike forum; and your other posts which are usually about bike stuff, but wrong.
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  21. #71
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    I think he changed the diagram!

    But is just a diagram, that doesn't make it true. Most here still believe that it elonigates cause you can measure it,.... which makes it real.... not a diagram.

    Now you could take your chain apart to measure what you are proposing is the only thing that wears, but then once that is done, how are you going to get it back on the bike?
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  22. #72
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    Quote Originally Posted by duriel View Post
    I think he changed the diagram!

    But is just a diagram, that doesn't make it true. Most here still believe that it elonigates cause you can measure it,.... which makes it real.... not a diagram.

    Now you could take your chain apart to measure what you are proposing is the only thing that wears, but then once that is done, how are you going to get it back on the bike?
    I don't get how people can continuously misunderstand something so simple:

    The diagram is not to demonstrate that the pins and links can't or don't elongate. They do. The diagram demonstrates that one of the things that ALSO wears cogs is roller wear, because roller wear affects chain pitch when wrapped around cogs.

    Therefore, it doesn't make sense to just check chain elongation and discount the rollers.
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  23. #73
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    Quote Originally Posted by Kontact View Post
    That's funny. Your posts remind me of a troll, who alternates between personal potshots at people discussing technical bike stuff on, of all places, the mechanical section of a bike forum; and your other posts which are usually about bike stuff, but wrong.
    Well if you look at his description, he is the "Russian Troll Farmer".
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

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  24. #74
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    Quote Originally Posted by Kontact View Post
    I don't get how people can continuously misunderstand something so simple:

    The diagram is not to demonstrate that the pins and links can't or don't elongate. They do. The diagram demonstrates that one of the things that ALSO wears cogs is roller wear, because roller wear affects chain pitch when wrapped around cogs.

    Therefore, it doesn't make sense to just check chain elongation and discount the rollers.
    Roller wear does NOT cause the chain pitch to change and does not wear cogs. See http://pardo.net/bike/pic/fail-004/000.html. Pardo wrote: The important issue of chain wear is that the spacing changes, causing the chain to ride up on the sprocket teeth. Thus, it is important to measure pin/bushing wear. However, bushing/roller wear does not affect chain performance unless it becomes so severe that it affects structural integrity — the bearing is worn away, the roller fractures, or the like. Thus, bushing/roller wear should not be included in overall wear measurements.

    The standard procedure for measuring chain wear is to hold a ruler against the chain. With 1/2-inch spacing chain, 24 links should measure 12 inches new; if 24 links measures 12-1/8 inches, the chain has worn about 1%.

    Roller clearance is not even standardized among chain manufacturers, so that should tell you something about how unimportant it is and how measuring something that isn't standardized is irrelevant. The late Jobst Brandt also said roller wear does not cause cog wear.

  25. #75
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    Quote Originally Posted by Kontact View Post
    The diagram shows two chains with exactly the same pin and link dimensions. Zero elongation. I made the diagram, I measured the distance between pins with a caliper. Zero.
    The worn chain is CLEARLY elongated in that diagram. Here are the two chains from your diagram side by side:

    Name:  compared.png
Views: 88
Size:  10.5 KB

    It is patently obvious that the distance between the pins AND rollers on the worn (orange) chain is greater.

    We must not be talking about the same thing. Do you have a different version of this diagram that you mixed this one up with?
    Attached Images Attached Images  
    Last edited by kapusta; 01-02-2018 at 12:01 PM.

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