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  1. #1
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    BB 68 X 110.5mm ISO to 68 X 113mm JIS Issues

    So I'm trying to figure out if I would have any Issues going from a
    BB 68 X 110.5mm ISO to a 68 X 113mm JIS
    This is on a 2011 Jamis Earth Cruiser 3 (I removed the 3-speed)
    I’m converting it to single speed. I want to change the 44T original crankset with a 46T or larger 48T max. In so doing most if not all the single speed cranksets I have seen and like require JIS and not ISO square taper. I'm a bit perplexed as the last time I messed with any bottom bracket was 40+ years ago on a Stingray, Cups and Ball bearings... Needless to say things have really changed.

    Any info would be greatly appreciated..!!

    Thanks

  2. #2
    Senior Member Bill Kapaun's Avatar
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    Shouldn't be a problem.
    The main thing is you are using the same shell width @ 68MM.

  3. #3
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    the main issue between JIS and ISO spindles isn't the taper angle, but the width of the taper at the center, or put another way, the width of the raper at the small end. This changes how far a crank arm will come up on the taper, and can cause problems in chainline, chainstay clearance and, in extreme cases, the end of the spindle coming through the crank so it cannot be tightened (the flip side is inadequate engagement of the arm which will ride on the tip of the spindle).

    I can't predict in advance how this will play out for you, and it might work out fine, but be ready to make adjustments if it doesn't.
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  4. #4
    Senior Member Bill Kapaun's Avatar
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    Poster said he is changing the crank set, so I assume they are going with the recommended cartridge type & length

  5. #5
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    Excellent info...
    Thanks

  6. #6
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    So I'm pretty clear now on the difference between the ISO and JIS taper and crank arm seat depth

    And the difference between the 110.5 and 113 shouldn’t cause a worry.

    The recommended for the crankset I’m looking at is for 68X113mm JIS Englishthread.

    Thanks for the info.

    It has been greatly appreciated

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