cassette, Rd and chain length ??
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  1. #1
    Man, I need a shower !
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    cassette, Rd and chain length ??

    I currently have a 13-29 cassette (that I use primarily for long mtn climbs) with what I assume is a long cage Campy RD. I'm getting another wheel set for use with the same bike, but want to go to different cog ratios for more typical training rides. Since there is concern for chain length, etc., what's the smallest large cog that would be compatible with this set up - would either a 12-25 or 13-26 work?

    Thanks

  2. #2
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    Quote Originally Posted by fasteddie
    I currently have a 13-29 cassette (that I use primarily for long mtn climbs) with what I assume is a long cage Campy RD. I'm getting another wheel set for use with the same bike, but want to go to different cog ratios for more typical training rides. Since there is concern for chain length, etc., what's the smallest large cog that would be compatible with this set up - would either a 12-25 or 13-26 work?

    Thanks
    Any of the two cassette should be fine, with your present setup, the long RD will take up the chains extra slack.

    Rick

  3. #3
    RoadBikeReview Member
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    think about it...

    Quote Originally Posted by fasteddie
    I currently have a 13-29 cassette (that I use primarily for long mtn climbs) with what I assume is a long cage Campy RD. I'm getting another wheel set for use with the same bike, but want to go to different cog ratios for more typical training rides. Since there is concern for chain length, etc., what's the smallest large cog that would be compatible with this set up - would either a 12-25 or 13-26 work?

    Thanks
    The worst case condition is the little chainring and the 12T cog (which you should not use anyway). If the chain length is correct it will have some tension in this combination. This 1-tooth change is only equivalent to 1/4 inch of chain. The minimum increment that can be removed from the chain is 1-inch.

    Using a cassette with a smaller maximum cog changes nothing. You have the same cogs on the 13-29.

  4. #4
    A wheelist
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    Quote Originally Posted by fasteddie
    I currently have a 13-29 cassette (that I use primarily for long mtn climbs) with what I assume is a long cage Campy RD. I'm getting another wheel set for use with the same bike, but want to go to different cog ratios for more typical training rides. Since there is concern for chain length, etc., what's the smallest large cog that would be compatible with this set up - would either a 12-25 or 13-26 work?

    Thanks

    You only need to be concerned that you have enough chain to span the big/big combo - if that combo is selected by mistake (as it's not normally a usable combo due to severe chain angle). Damage will result if you don't have enough. With smaller large cogs you will then have a little extra chain - no big deal.
    .

  5. #5

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    Quote Originally Posted by Mike T.
    You only need to be concerned that you have enough chain to span the big/big combo - if that combo is selected by mistake (as it's not normally a usable combo due to severe chain angle). Damage will result if you don't have enough. With smaller large cogs you will then have a little extra chain - no big deal.
    If you use the big-big measuring method you'll have to extend your chain if you switch from let's say a 11-21 to a 12-25. With the small-small method you won't.

  6. #6
    A wheelist
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    Quote Originally Posted by divve
    With the small-small method you won't.

    And by that method you'll only have enough chain by chance, not by choice. That's not a method SRAM endorses and they make chains.
    .

  7. #7

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    Small-small isn't by chance. It's always correct provided you stay with-in the derailleur wrap capacity. Campagnolo describes this method in their manual and they make 10 speed chains which SRAM hasn't even heard of

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