Crank/Chainline/Bottom Bracket Help- Mtbr.com
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  1. #1
    That roadie in your way
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    May 2006
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    Crank/Chainline/Bottom Bracket Help

    Yeah, I'm a little confused. I have an old Rock Lobster Cross frame that is spaced for 130 (think it was respaced from 135 at some point in it past life), an old crankset and bottom bracket from an early 80s 10 speed, and a fixed/free track hub that has been respaced to 130.

    Its an old double crank and I had to move the chainring to the outer position to allow for frame clearance. With the bottom bracket and crankarms installed I have very little clearance between the frame and the crankarm, currently less than a quarter inch on the non drive side. As things are now, I can achieve a proper chainline but the narrow clearance is bothering me. If I go with a wider BB, I think the chainline may be a problem. Is there something I'm missing?

  2. #2
    Out spokin'
    Reputation: Sparticus's Avatar
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    Quote Originally Posted by crumjack
    Yeah, I'm a little confused. I have an old Rock Lobster Cross frame that is spaced for 130 (think it was respaced from 135 at some point in it past life), an old crankset and bottom bracket from an early 80s 10 speed, and a fixed/free track hub that has been respaced to 130.

    Its an old double crank and I had to move the chainring to the outer position to allow for frame clearance. With the bottom bracket and crankarms installed I have very little clearance between the frame and the crankarm, currently less than a quarter inch on the non drive side. As things are now, I can achieve a proper chainline but the narrow clearance is bothering me. If I go with a wider BB, I think the chainline may be a problem. Is there something I'm missing?
    If you go with a longer spindle, you could move the ring to the crank's middle position.

    I admit that "less than a quarter inch" is a bit close, but if it doesn't hit... is there really a problem? I'm just sayin'...

    --Sparty
    disciplesofdirt.org

    We don't quit riding because we get old.
    We get old because we quit riding.

  3. #3
    That roadie in your way
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    Quote Originally Posted by Sparticus
    If you go with a longer spindle, you could move the ring to the crank's middle position.

    I admit that "less than a quarter inch" is a bit close, but if it doesn't hit... is there really a problem? I'm just sayin'...

    --Sparty
    I may end up doing that. My concern with the small clearance was my heel hitting the chainstay. I called my LBS and their concern was flexing the crankarm into the chainstay. That seems like a lot of flex but it could be possible. I guess I'll just build, ride, and see what happens.

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