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  1. #1
    nnn
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    Converting 8sp cassette to a 7sp

    Well I haven't been around for a long time.

    Anyway my question is, is it possible to convert an 8sp cassette to a 7sp by removing one sprocket and spacer, and perhaps using the 7sp spacers to use as a 7sp cassette ?
    I'm asknig because 7sp cassettes are rarely sold these days, but it would cost me an arm and a leg to convert (integrated shifting etc etc) and I'm more than happy with a 7sp setup.
    Last edited by nnn; 01-28-2006 at 08:04 AM.

  2. #2
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    Quote Originally Posted by nnn
    Well I haven't been around for a long time.

    Anyway my question is, is it possible to convert an 8sp cassette to a 7sp by removing one sprocket and spacer, and perhaps using the 7sp spacers to use as a 7sp cassette ?
    I'm asknig because 7sp cassettes are rarely sold these days, but it would cost me an arm and a leg to convert (integrated shifting etc etc) and I'm more than happy with a 7sp setup.
    The spacing of the cogs is slightly different, 8 speed uses 4.8 mm c-c cogs and 7 speed uses 5.0 mm c-c cogs.
    There is no added value to my participation - in fact, just more confusion.

  3. #3
    Chrome Toaster
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    I suppose its perfectly possible but would likely require quite a bit of work to get the right spacing. If you get a lower end cassette which are usually the kind with complete cogs that are riveted together you can drill out the rivets and loosen all the cogs. You'll need to replace the spacers in between each cog to get the right seperation. Standard Shimano H.G. 7 speed sprockets are 5.0 mm in seperation with each sprocket being 1.85mm thick and spacers 3.15mm. 8 speed HG is 4.8mm in seperation with 1.8mm sprockets. Spacers are 3.0mm.

  4. #4
    Ebo
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    You can easily find 7 spd cassettes on Ebay, Nashbar, Cambriabikes, Bikeman, AEbike, etc.

  5. #5
    AKA Frank N. Bike!!
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    Quote Originally Posted by GearHead
    The spacing of the cogs is slightly different, 8 speed uses 4.8 mm c-c cogs and 7 speed uses 5.0 mm c-c cogs.
    If that's true why is it I can run a 7 speed rapid fire shifter on a 8 speed cassette with NO ghost shifting?
    My Bike: '03 Specialized HardRock FrankenBike
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  6. #6
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    Quote Originally Posted by Kona0197
    If that's true why is it I can run a 7 speed rapid fire shifter on a 8 speed cassette with NO ghost shifting?
    I don't know, maybe you aren't very sensitive to bad shifting. I didn't make this up Shimano and SRAM did. Here is a link that goes through it in detail.

    http://sheldonbrown.com/k7.html
    There is no added value to my participation - in fact, just more confusion.

  7. #7
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    Quote Originally Posted by Kona0197
    If that's true why is it I can run a 7 speed rapid fire shifter on a 8 speed cassette with NO ghost shifting?
    Becuase the difference is quite small and derailleurs have a certain amount of tolerance for slop before you start to notice problems. You can get good enough shifting under some conditions but it will be hard to det ideal shifting over all setups.

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