Chain length

Discussion in 'Cycling Equipment' started by Phill P, Dec 29, 2007.

  1. Phill P

    Phill P New Member

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    How do you know the correct chain length?

    I'm going from a 11-23 cassette, to a 12-25 cassette. I'm assuming I just need to make the new chain 2 links longer than the old chain to cover the extra 2 teeth on the cassette, and the jockey cage will still be able to deal with the extra length when in the 12 tooth.

    Or do I just need to add one link and split the difference at each end of the cassette?
     
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  2. kdelong

    kdelong Well-Known Member

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    This is a good question and I would like to know the answer too. Is there any accurate way of calculating the number of links required in a chain based upon the cassette and chain rings? I always just use the same length chain as the one I am replacing if I am not changing cassettes or chainrings. If I do change these, I just place the chain on the largest chainring and largest cog, pull the chain until the derailler cage is pulled close to its limit, remove the excess links and connect the chain there. Then I place it on the smallest cog and chainring to make sure that there is no slack in the chain. If there is slack, I just remove enough links to get some tension, and reconnect. This works, but can get expensive if you are using Shimano chains that require the special pin, and have to make a couple of adjustments.
     
  3. Retro Grouch

    Retro Grouch New Member

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    First, take a good look at your chain. You can't add just 1 link.

    The quick, dirty test is to gingerly try to shift into your big/big combination. If it'll shift up into that combination (my bet) and still give you a little chain slack you're good-to-go.

    Don't try doing this by pedaling up a hill with all of your might unless you're interested in buying a whole new bike.
     
  4. Peter@vecchios

    [email protected] New Member

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    Small ring and small cog..then ensure you have about 5mm from the chain as it exits the lower pulley and RD body..works for any system..

    As for Ceramic bearing balls..I think you should shamelessly mention that writers(engineers) to Velonews state you should see about a 1% increase in wattage with all ceramics thruout your bike..BB, pulleys, hubs, plus longevity of the balls certainly, but the steel cones and cups will not be effected and may wear sooner, due to the hardness of the grade 5 ceramics....not sure it's worth the $400+, IMHO
     
  5. sideshow_bob

    sideshow_bob New Member

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    I'm sure you could build a formula to calculate it, but there are more variables than just the size of the cassette and the chainrings. The bike's geometry will be significant, specifically the lengths of the chainstays.

    In regards to the OP, unless the chain has been fit on to the minimum length, you will probably find that going to a 25 should be okay without modifying the chain. But it really depends on the big/big combination, ie can you shift into it. I'd simply put my bike on a stand and see how the system looks in the big/big combo.

    FWIW I use SRAM cassettes and routinely swap out wheels between the 11-23 and 11-26 combo's without any adjustment to the chain.

    --brett
     
  6. Phill P

    Phill P New Member

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    Campybob...thanks, the park tool webite pretty much says it all. Pretty much what I was thinking I'd need to do, just didn't know the correct conditions etc. Better to be sure than sorry!

    Peter......some people like/want the ceramic balls some don't. I don't sell a set of ceramic balls for $400, I buy direct from the manufacturer so the price stays waay lower since there aren't markups from going through multiple hands. I don't sell a great deal of them, its just a hobby. I also now sell a few nylon bolts for bolt cages and deraillors. All just a bit of fun.
     
  7. michaeltop

    michaeltop New Member

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    download the chain length calculator at http://www.machinehead-software.co.uk/

    there are a couple other cycling programs available as well

    cheers,
    topo
     
  8. OldGoat

    OldGoat New Member

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    If you use a Wippermann Connex link instead of the Shimano pin, you won't have this problem/expense.
     
  9. Phill P

    Phill P New Member

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    I'm using KMC chains that come with the missing link (same as a wippermann??)
     
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