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  1. #1
    I'd rather be riding Noif666's Avatar
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    bmx/mtb compatibility

    I'm building up an SS mtb and am using a bmx freewheel with an mtb crankset. I'm wondering whether it's ok to run a bmx chain with mtb chainrings as a mtb chain will obviously not work with the bmx freewheel hub?
    I tried a google search but only got a bunch of online shopping sites
    Thanks

  2. #2
    ÖöÖöÖöÖöÖö Dannihilator's Avatar
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    It can be done.
    You have two choices in doing this.

    Option 1: get a SS specific chainring for the crankset and use the chain.

    Option 2: For the crankset, get a set of profiles and put on a BMX Chain Ring. And run it like that with a bmx chain.

    The hardest part with either of these is finding a BMX chain that is long enough.
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  3. #3
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    1/8" BMX chains will work on 3/32" chainrings, not a big deal, but it will probably be noisier.. Or you could just get a 3/32" freewheel

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    ÖöÖöÖöÖöÖö Dannihilator's Avatar
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    Or run an 8 speed chain.
    Strike like an eagle and sacrifice the dove.
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  5. #5
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    8 speed chain is 3/32" too narrow for a 1/8" bmx freewheel, it wont seat properly.

  6. #6
    ÖöÖöÖöÖöÖö Dannihilator's Avatar
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    Then a 7 speed will do.
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  7. #7
    Retrogrouch in Training bostontrevor's Avatar
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    You can get 3/32" freewheels just fine. My mountain bike is quite happy with a 20t 3/32" ACS.

  8. #8
    Senior Member sydney's Avatar
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    Quote Originally Posted by KonaRider24
    Then a 7 speed will do.
    Get it straight.All derailer chains are 3/32" inside width.

  9. #9
    ÖöÖöÖöÖöÖö Dannihilator's Avatar
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    Quote Originally Posted by sydney
    Get it straight.All derailer chains are 3/32" inside width.
    Guess what, you're wrong, not all chains are 3/32'' inside width check a 9speed chain lately?

    Between the outer plates: 1/4"

    Between the inside plates: 1/8"

    But yeah there is only a hair of a difference between a 7 and an 8. After having awhile to think the chain reccomendations I'd just go with a BMX chain. When shimano developed the 9 speed system, they couldn't get the width of an 8 speed to have the proper clearance, so they had to make a narrower chain to work with a 9 speed system.
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  10. #10
    Senior Member sydney's Avatar
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    Quote Originally Posted by KonaRider24
    Guess what, you're wrong, not all chains are 3/32'' inside width check a 9speed chain lately?

    Between the outer plates: 1/4"

    Between the inside plates: 1/8"

    But yeah there is only a hair of a difference between a 7 and an 8. After having awhile to think the chain reccomendations I'd just go with a BMX chain. When shimano developed the 9 speed system, they couldn't get the width of an 8 speed to have the proper clearance, so they had to make a narrower chain to work with a 9 speed system.
    Wrong again. The inside width of a shimano 9 speed chain is the same as the 8. It's the outside width that is narrower to accomodate the closer cog spacing.Check Sheldon Brown at www.harriscyclery.com

  11. #11
    ÖöÖöÖöÖöÖö Dannihilator's Avatar
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    Quote Originally Posted by sydney
    Wrong again. The inside width of a shimano 9 speed chain is the same as the 8. It's the outside width that is narrower to accomodate the closer cog spacing.Check Sheldon Brown at www.harriscyclery.com

    The tell me this, how come I did a physical measurement and got the numbers I did then? Oh wait, I was measuring a sram, grabbed the wrong peice of chain. God I've been in a funk lately.
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  12. #12
    I'd rather be riding Noif666's Avatar
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    Quote Originally Posted by KonaRider24
    It can be done.
    You have two choices in doing this.

    Option 1: get a SS specific chainring for the crankset and use the chain.

    Option 2: For the crankset, get a set of profiles and put on a BMX Chain Ring. And run it like that with a bmx chain.

    The hardest part with either of these is finding a BMX chain that is long enough.
    I think I'm leaning more towards option 2 as it is easier to get them as second hand parts than it is SS specific parts. Something about SS not being as widespread here in Oz...silly multi-speeders
    thank you all for your input, it gives me a few options to ponder.

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