Bottom Bracket/Chainline Question

Discussion in 'Singlespeed' started by fixedgearpaddy, Mar 4, 2008.

  1. fixedgearpaddy

    fixedgearpaddy New Member

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    I have assembled all parts for a new Salsa Casseroll build with the exception of a Phil Wood bb since I was unsure which length to get to achieve the best chainline. The Casseroll has 130mm rear spacing and forward-entry horizontal dropouts allowing me to run fixed/ss/ or geared setups. Should I go with the cranks spec'd length of 113mm allowing for possible future use in a geared setup? or is there a better alternative with a decreased q factor?

    Here are the drivetrain parts that I am working with:

    NOS- Shimano 105 FC-1055 (double) cranks
    44T surly chainring
    3/32 16T EAI cog
    3/32 White Industries freewheel
    130mm Paul Comp. high flange hub fixed/free/ Paul lockring

    Thanks for any and all help!

    Chris
     
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  2. alfeng

    alfeng Well-Known Member

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    What is your option -- 107mm?

    At first blush, I presume you are thinking that the chainine will be ~3mm off if you opt for the 113mm BB spindle ... BUT, I think that those 107mm spindles are really intended for:
    • a crank which uses a symmetrical spindle
    • a frame with 120mm rear spacing & you've got 130mm rear spacing
    Is the flange spacing WIDER (as I believe they are on a SURLY rear hub) OR do they have the traditional separation?

    If wider, I presume the hub is more-or-less intended to be used with a standard length BB spindle. Ask the vendor.

    FWIW. Personally (not that it should matter what 'I' think or would choose to do), I would opt for the "normal" BB spindle because a slight offset (if it exists) does not matter with a Single Speed freewheel ...

    If you're concerned with the offset on the Fixed side, presuming a threaded axle, you can adjust the dish on the rear wheel so that the Fixed cog lines up perfectly with the chainring & allow the freewheel side to be slightly off line.

    To state the obvious, you can mount the chainring on EITHER the inner OR outer shoulder ...
     
  3. yoxi5236

    yoxi5236 New Member

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  4. daveornee

    daveornee New Member

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    You want to end up with a 44 mm chain line for the best results with the Paul hub. You need to get the BB length and crank that gets you to 44 mm.
     
  5. alfeng

    alfeng Well-Known Member

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    THAT may be true ...

    BUT, let me add (belatedly, since I presume you've finished putting the bike together), if you are using a regular ROAD chain, you actually have a lot of latitude (at least 5mm) with regard to the chainline on a Single Speed ... so, having the perfect chainline becomes more of a cosmetic issue.
     
  6. daveornee

    daveornee New Member

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    Straighter chain improves efficiency and extends chain life, but derailer chains do work without having well aligned cog/chainwheel.
    Less expensive BMX/single-speed/track chains wear & work well with well aligned cog/chainwheel. + if you like the colorful ones, they seem only to come in single-speed/BMX.
     
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