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  1. #1
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    EighthInch Courier Crankset, EighthInch Bottom Bracket

    Hello,

    I've searched but found conflicting information. I think this may be a result of specifications changing over time. I've also read this: Square Taper Bottom Bracket Interchangeability.

    My question is as follows:
    I purchased the EighthInch Courier Crankset (EighthInch Fixed Gear/Single Speed Cranks |EighthInch Courier).
    The product specifications state the following:
    Crank: Chainring BCD 144 BCD
    Crank: Recommended Spindle Length 110 mm
    Crank: Spindle Interface Type Square Taper JIS
    But the box states, "110mm ISO bottom bracket recommended."

    I also purchased the EighthInch Square-Taper Bottom Bracket (EighthInch Bottom Brackets | EighthInch Square-Taper Bottom Bracket). I chose a spindle length of 110mm. The website states, "The 110mm works well with our EighthInch Courier crank."
    The box states the following:
    - 68mm shell width
    - ISO/english threading (1.37" x 24tpi)
    - JIS square taper spindle
    - crank bolts included

    Are these two truly compatible? Will 110mm give me the straightest chainline? Should I simply contact EighthInch?

    Thank you.

  2. #2
    Blaster of Reality Scrodzilla's Avatar
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    My shop stopped carrying that crankset because EighthInch is stupid and couldn't tell me what BB to actually use. I eventually found that using a 107mm JIS spindle works the best.

  3. #3
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    I have the courier cranks

    Quote Originally Posted by Scrodzilla View Post
    My shop stopped carrying that crankset because EighthInch is stupid and couldn't tell me what BB to actually use. I eventually found that using a 107mm JIS spindle works the best.
    If I could resurrect an old thread here.......I run my cranks with the 110 mm eighthinch bottom bracket. The chain line looks straight to me but I haven't measured it if its actually 42mm. Even if I did measure it, no guarantees I could get it accurate enough to within a few mm. I like these cranks by the way. They are nice and thick and of course 144 bcd. It's ugly though. I tossed the stock chainring and picked up a 7075 47t and I'm good to go.

  4. #4
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    So to continue talking to myself and for the sake of Internet posterity I did some more accurate measuring of these cranks. I measured the circumference of my seat tube using a string and calculated its diameter and then placed a ruler against it to find that with the 110 bottom bracket you get a 43.18 mm chain line. With the 107 spindle BB that Scrod suggested you would get a 41.68 chainline. So Scrod is technically closer to the magical 42 mm chainline. Is this guy ever wrong? I'm not changing my BB though as its close enough for me and maybe even closer to my formula hub all city cog combo rear chain line. I can't be exactly sure but we are talking about a minuscule difference only hardcore bike nerds would even care about.
    Last edited by ufbeans; 02-23-15 at 08:23 AM.

  5. #5
    Blaster of Reality Scrodzilla's Avatar
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    Quote Originally Posted by ufbeans View Post
    Is this guy ever wrong?
    No.

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