Chain Measurement to replace

Discussion in 'Cycling Equipment' started by OscarC, Nov 28, 2007.

  1. OscarC

    OscarC New Member

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    Hi all,
    I use the Park tool to measure and replace my Dura Ace 10-speed chain. A new chain measures .25". I have been replacing my chain once it gets to .75" to reduce cassette and crank wear. The tool says to replace at 1.0". I wonder if I should run the chain till it gets to the 1.0". At what measurement does everyone else replace their chains? What are your thoughts?

    thanks in advance for your reply.

    Oscar.
     
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  2. sogood

    sogood New Member

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    1" stretch on a 12" segment would have been... Wow!

    1% stretch is probably a bit late. IIRC, Campagnolo recommends replacement at 0.5% stretch. At 1%, you are potentially looking at replacing the cassette or going to encounter skips with the new chain in the near future.
     
  3. OscarC

    OscarC New Member

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    I think those measurement on the tool are meant to be over the entire run of the chain measured over a few links. Kinda like when you take your heart rate. Count for 10 seconds and then multiply by what ever. But I could be wrong.
     
  4. sogood

    sogood New Member

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    Still won't be 1", even over the full length of an average chain.
     
  5. OscarC

    OscarC New Member

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    ok you we're right, I looked it up on the Park tool website. It says the numbers are a % of stretch. So a new chain is .25% stretched. It also says "To alleviate poor shifting and uneven drive train wear, most manufacturers recommend chain replacement at or before 1% stretch."

    So on a chain that is 55", then;

    A new chain is - .25% or .1375" stretched.

    .5% is .275" stretched
    .75% is .4125" stretched
    1% is .55" stretched

    Wow, 1% is almost the length of a link. Maybe .75% is a good time to replace?
     
  6. dhk2

    dhk2 Active Member

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    The Park CC-1 gauge I've got has two sides; .75 and 1.0%. When the 0.75% side drops in, you've got a stretch of .09" over a foot of chain. In the old school, using a ruler, the standard was 1/8 (.125") wear per 12 inches, which is of course just more than 1%.

    IMO, replacing at .75% makes sense if you're going to reuse the cassette on the replacement chain, since cassette wear will be less (resulting in better life of the second chain). If you'll be changing out the cassette with the chain, no need to change before the 1% wear limit since you don't care about saving the cogs.
     
  7. xbgs351

    xbgs351 New Member

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    [​IMG]

    I have one of these. I also have a vernier caliper. If I was to use the Park tool to decide when to replace my Campag chains, the chains would probably have about 100,000km on them before replacing. The Park tool will not even fit in a new Campag chain, so there is no way that it will read 0.25 to 0.50 for a new chain.

    The best method is to use a vernier caliper along with the campag recomendations as found on the next post.
     
  8. sogood

    sogood New Member

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    Campag's spec.

    [​IMG]
     
  9. scotty72

    scotty72 New Member

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    Yes,

    Last weekend I replaced a badly worn chain >1%. When I laid out old next to new, there was about 3/4 of a link stretch. Quite amazing. Letting it go that long really did stuff my cassette - changed that too.

    If you're going to do it properly maybe a rule of thumb might be .75%, think about and order a new chain. 1% = hurry the hell up! :)

    Scotty
     
  10. OscarC

    OscarC New Member

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    That is quite a huge difference if the Park tool doesn't even drop into a Campy Chain. I never realized the Shimano and Campy chains we're so different in specs.

    I could never imagine having to replace my Dura Ace cassette ($170) every time I replace my chain ($40.00). I get about 2,000 miles to get to .75%. Not sure how that compares to other cyclist out there. I ride mostly mountians, all climbing if possible.

    It doesn't make sense to me to use the Campy chain specs
    to measure the Dura Ace chains if they are different measurements to begin with unless I'm totally missing something here.
     
  11. sogood

    sogood New Member

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    All chains have the same spec from a length point of view and this came from pre-historic times. They do vary by width based on the number of speeds and manufacturer.

    Campy's spec only refers to the chain. You typically don't have to replace the cassette when the chain has stretched 0.5%.
     
  12. artemidorus

    artemidorus New Member

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    On the contrary, Scotty, when you get to 1% you've got all the time in the world. Keep riding until that chain starts to skip, because you've already stuffed your cassette and your favourite chainring.
     
  13. dhk2

    dhk2 Active Member

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    Well, why not get to 1% or even 2% and let the cassette wear out along with the chain? Haven't done this myself, but could be it's a cost-effective strategy?

    I've only been keeping records since I got a new bike in 04. Using 0.75% as a the replace limit on the chain, the first SRAM PC-99 lasted 6K miles, the second (running on the used DA cassette only lasted 4K. When I bought the replacement chain, my friendly LBS mechanic warned me that a 10K mile DA cassette was liable to skip with a new chain, and sure enough, it did. The second replacement chain, HG-93, now has 5300 miles on it (on new cassette) with the gauge showing plenty of miles to go.

    So, from my limited experience, appears new chains last a good bit longer on a new cassette. If that's true, why not just use the original chain and cassette until it skips under load, or gets noisy, and then replace both together? EG, run the chain and cogset for 12-15K miles, then replace them as a set. Note, I'm ignoring the front chainrings since I've never had a problem with them.
     
  14. scotty72

    scotty72 New Member

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    That was said a little tongue in cheek.

    As my earlier post said, I let my last chain get to 1% and it chewed up the cassette and then spat it back out. That's why I said .75 means order a chain (should only take a few days at worst).

    BTW. The 1% killed the cassette but the rings were as good as gold.

    Scotty
     
  15. xbgs351

    xbgs351 New Member

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    Perhaps because it can hurt when the chain breaks.
     
  16. dhk2

    dhk2 Active Member

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    Sure, but is a chain that's worn to say 2% really significantly weaker than one worn at 1%? I've only had one chain that "broke". It lost a bushing with only 200 miles or so on it. I was JRA, really, and heard a pop. The chain was making a clicking sound for the rest of the ride, but I didn't realize what had happened until I got home.

    Other than that, have seen chain damage from popping out of gear, or a shift under heavy load. But unless a chain experiences some kind of severe overload like this, doubt the links would just fatigue with mileage and snap unexpectedly. I may be wrong of course, since I've not be willing to run a chain (and cassette) to failure. As you said, that could be a painful experiment :)
     
  17. sogood

    sogood New Member

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    Chain out of spec not only increase the wear but also leads to poor performance. So if you enjoy poor shifting and regular skips, then by all means.
     
  18. Albert 50

    Albert 50 New Member

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    If you change your chain at any of the parameters mentioned before you will still eventually need to replace your rings & cogs :)
    I alternate 4 chains at 1k ks. I'm working on the theory that by the time each chain has done maybe [hoping] 5k ks, which is 20k ks, I'll be happy to replace rings & cassette.
    Anyway, just another alternative to consider in the quest for getting maximum value out of your $s.

    Edit: This thread on BF has Hillrider & Operator saying alternating chains is a crapola idea. :)
     
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