Cycling Equipment · Public discussion

chainline worries plus front derailleur query

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Cycling Equipment
Published
14 May 2005
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15 May 2005
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  1. Hi

    I'm completely new to bike building but am having a go with some old
    and new bits and alot of reading up ...

    So far, I have two wheels self-built. The rear is Mavic Open Pro, 32x3
    DT Competition, Shimano Ultegra hub, SRAM PC950 cassette. I've got a
    PC990 chain. I'm going to go with Ergopower levers and the rest of the
    components might be Campagnolo unless anyone suggests otherwise (this
    is mainly so I don't have to worry about compatibility but, from what
    I've read, as long as the rear derailleur and the indexed gear
    manafacturers are the same then everything else can be mixed and
    matched for 9 speed).

    The frame to be used is a Reynolds 653 frame from 1989, used to be a 7
    speed Ultegra. Anyway, measured the rear drop-out spacing as 128mm. I'm
    not sure if I should be worried about chainline. Clearly, the current
    spacing is 2mm too narrow for the hub. My current thought is I should
    just go and get a crank and compatible bottom bracket and hope it's OK
    and, if not, get the local bike shop to realign the rear hanger and
    cold set the frame. Is there any better approach? Is there any way I
    can find out the best bottom bracket spindle length? From
    http://www.parktool.com/repair_help/clg2.shtml, I calculated my rear
    cog middle and I get 41.25mm (assuming 130mm drop out once stretched a
    bit). Zinn's book says the chainline should be around 42mm if possible
    (I can't really work out why this is so). Both Campagnolo and Shimano 9
    speed front double cranks are 43.5mm and Park say "Manufacturers
    typically specify a front crankset chain of slightly longer than the
    rear chainline.". So I think I'm OK with either manufacturer. Apart
    from I want 167.5 mm crank arms :-)

    One more little thing: I measure my seat post's circumference as 88.5mm
    so that's 28.2mm diameter. I need a band on double front derailleur -
    the smallest campagnolo or shimano make is 28.6mm! Sounds silly but is
    that going to be OK?

    Cheers

    ccc rider

  2. Quoted message said:

    Hi

    I'm completely new to bike building but am having a go with some old
    and new bits and alot of reading up ...

    So far, I have two wheels self-built. The rear is Mavic Open Pro, 32x3
    DT Competition, Shimano Ultegra hub, SRAM PC950 cassette. I've got a
    PC990 chain. I'm going to go with Ergopower levers and the rest of the
    components might be Campagnolo unless anyone suggests otherwise (this
    is mainly so I don't have to worry about compatibility but, from what
    I've read, as long as the rear derailleur and the indexed gear
    manafacturers are the same then everything else can be mixed and
    matched for 9 speed).

    The frame to be used is a Reynolds 653 frame from 1989, used to be a 7
    speed Ultegra. Anyway, measured the rear drop-out spacing as 128mm. I'm
    not sure if I should be worried about chainline. Clearly, the current
    spacing is 2mm too narrow for the hub. My current thought is I should
    just go and get a crank and compatible bottom bracket and hope it's OK
    and, if not, get the local bike shop to realign the rear hanger and
    cold set the frame. Is there any better approach? Is there any way I
    can find out the best bottom bracket spindle length? From
    http://www.parktool.com/repair_help/clg2.shtml, I calculated my rear
    cog middle and I get 41.25mm (assuming 130mm drop out once stretched a
    bit). Zinn's book says the chainline should be around 42mm if possible
    (I can't really work out why this is so). Both Campagnolo and Shimano 9
    speed front double cranks are 43.5mm and Park say "Manufacturers
    typically specify a front crankset chain of slightly longer than the
    rear chainline.". So I think I'm OK with either manufacturer. Apart
    from I want 167.5 mm crank arms :-)

    One more little thing: I measure my seat post's circumference as 88.5mm
    so that's 28.2mm diameter. I need a band on double front derailleur -
    the smallest campagnolo or shimano make is 28.6mm! Sounds silly but is
    that going to be OK?

    A 130mm hub in a 128mm frame is not even difficult. Yes,
    have it aligned when convenient . When you do, ask to see
    the gauges in your frame. Most frames aren't accurate to 2mm
    so the alignment will both make wheel changes easier and
    also ensure it is straight.

    Spindle length is related to brand/model of crank. What
    crank? And an idealized 41.25 CL _is_ 42 for all practical
    purposes.

    What frame is it? An older metric tube may well be 28.0mm
    in which case just add one layer of cotton bar or rim tape
    between changer clamp and frame.

    --
    Andrew Muzi
    www.yellowjersey.org
    Open every day since 1 April, 1971

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