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  1. #1
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    how to measure wear on gears

    I bought an '84 Fuji Del Rey. The chain was stretched by 1/16-1/8, and had to replaced. the cogset was also replaced. the front gears are still the old ones, and I'm wondering if I need to replace those as well.

    When I pedal, I can hear the chain clicking with the gears. I've lubed up the chain pretty good, and it's still doing that.

  2. #2
    Constant tinkerer FastJake's Avatar
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    Chainrings usually last pretty long. I've never actually had a problem with one, despite all the old bikes I ride. Can you post a picture of them? Are you sure the clicking is coming from the front?
    Why "derailer" is the correct way to spell the gear-change mechanism: sheldonbrown.com/derailer.html

  3. #3
    bike whisperer Kimmo's Avatar
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    What kind of clicking? The quiet whir of the chain wrapping around your jockey wheels, or the horrible clatter of the chain catching on larger cogs, for instance?

    IME worn chainrings produce a throbby feeling through the pedals under power; the teeth have a shark-fin look. Post a pic of your rings.

  4. #4
    Senior Member Shimagnolo's Avatar
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    I had a bike I used for years as a commuter.
    The steel chainrings were worn to a sharks-tooth shape, but still worked w/o problem when I finally junked the bike.
    I've never replaced a chainring due to wear.

  5. #5
    bike whisperer Kimmo's Avatar
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    I'd hazard a guess steel and ally rings are apples and oranges.

    As far as I can figure, a chainring can wear and wear and it's not a problem until either the teeth have enough of a hook to cause friction as the rollers are dragged over them, or the effective diameter of the chainring is reduced enough to space the pins too close. Chain wear could potentially mask the former effect, and I'm pretty sure I've noticed a ring I previously thought was still okay throb with a new chain.
    Last edited by Kimmo; 05-21-11 at 11:03 PM.

  6. #6
    Quirky Grifter LesterOfPuppets's Avatar
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    I've had increased chain suck on worn MTB rings. I've got a couple of completely wasted inner road rings that never caused me any problem though. But, you can tell they're wasted when the teeth get asymmetrical.

    Oh, I remember reading about techniques for figuring chainring wear based on how far you could pull the chain away from the ring. Forget exactly how that went and it seemed pretty vague at the time, though.
    Last edited by LesterOfPuppets; 05-21-11 at 11:19 PM.
    1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1997 KHS Comp * 1990-ish Scapin * Lemond Buenos Aires Triple

  7. #7
    bike whisperer Kimmo's Avatar
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    Quote Originally Posted by LesterOfPuppets View Post
    Oh, I remember reading about techniques for figuring chainring wear based on how far you could pull the chain away from the ring. Forget exactly how that went and it seemed pretty vague at the time, though.
    With a fresh chain, that would indicate the effective reduction of the chainring diameter. Prolly want to see how far you can pull a new chain from a new ring before inferring much from it, though.

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