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  1. #1
    Senior Member Velocirapture's Avatar
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    BB spindle length confusion

    I hope you guys can give me more guidance than google has so far.

    I'm about to buy a very lovely frame, that the manufacturer notes as having a english threaded 68 BB, and a 53.5 chainline (which seems a bit wide to me?)

    My current Pro-Lite Sardinia crankset will be built across - and the specs for this are BB:108mm JIS taper, with a 44mm chainline.

    Am i correct in undersatndint that 108mm is the recommended length of the spindle? (i have now discovered that square taper comes in many spindle lengths!)

    if 108 is not the recommended spindle length, would anyone be able to point me towards what would be.

    Additionally, is there some way to correct for the stated 44mm to 53.5mm, as almost 10mm is a big difference. (unless i am misunderstanding the frame info).

    Any imput on interpretting these numbers will be appreciated! i'm buying the frame and BB online, so wont be able to get input on the shop floor, so to speak.

    thanks

  2. #2
    aka mattio queerpunk's Avatar
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    Why does the manufacturer of your frame mention a 53.5 chainline? You might want to doublecheck that. Frames don't have chainlines - drivetrains do. 42.5mm is a track chainline - just about all hubs and cogs place the chainline there, so you want to set up your crank to match. +/- a millimeter or two is fine. 10 is well past pushing it.

    Yes, if your literature is correct, 108mm is the recommended length of the spindle. Note also that there are two different types of tapers - JIS and ISO. Confirm which type this Pro-Lite crankset is.
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  3. #3
    Senior Member Velocirapture's Avatar
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    ^ Thanks! that helps.

    I have a suspicion that the manufacturer may not have fully understood my question, as their help desk is not first language english. The crank is definitely JIS, that information came from the tech documents rather than my emailed query.

  4. #4
    aka mattio queerpunk's Avatar
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    OK.
    You're likely to have a bit of an easier time finding a 107mm spindle, which would be fine - it would bring your chainline in a half a millimeter, closer to the track standard of 42.5. It won't be dead on, but chains do have some side-to-side wiggle room and a millimeter, over the course of a drivetrain, is a very small amount.
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  5. #5
    Senior Member ftwelder's Avatar
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    Quote Originally Posted by queerpunk View Post
    Why does the manufacturer of your frame mention a 53.5 chainline? You might want to doublecheck that. Frames don't have chainlines - drivetrains do. 42.5mm is a track chainline - just about all hubs and cogs place the chainline there, so you want to set up your crank to match. +/- a millimeter or two is fine. 10 is well past pushing it.

    Yes, if your literature is correct, 108mm is the recommended length of the spindle. Note also that there are two different types of tapers - JIS and ISO. Confirm which type this Pro-Lite crankset is.
    Frames have a "minimum" chain line figure with a specific chain ring diameter in some cases.
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  6. #6
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    Quote Originally Posted by ftwelder View Post
    Frames have a "minimum" chain line figure with a specific chain ring diameter in some cases.
    I second that. Some might remember the trouble with certain Fuji frames and chainrings hitting the chainstay.

    My Sardinia crankset is mounted with a 110mm JIS BB, resulting chainline is 46mm. That's fine for me because the rear hub is an old Powertap. The crank is really close to my BB. I doubt that it would work with the 108mm version of this cheap german plasticky BB (I love 'em).
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