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  1. #1
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    Bottom bracket threading/size question (amateur hour)

    I've picked up an 80s era Fuji Sports 10. My goal is to turn it into a single speed commuter, but really I'm just taking it apart slowly and trying to learn some bike mechanics along the way (you'll see from my question that I'm new to this).

    I've gotten to the cranks and bottom bracket completely disassembled (why? the larger chainweel is attached to the crank and I wanted it gone, also the learning thing). The cranks were three piece cottered, I pounded the pins out easy enough and removed them, the axle and both the fixed and adjustable cups. I'm looking at and measuring the naked bottom bracket housing and I'm trying to determine exactly what I've got before I go about replacing parts (e.g. putting in a cartridge bottom bracket).

    I measure 70mm across the bottom bracket (from the outer edges) and the fixed cup screws in to the left, which confuses me because the research I've done tells me I shouldn't see this combination. Am I measuring incorrectly? Surely I'm doing something stupid, but on the small chance that I'm not, can I even get a bottom bracket cartridge to put into this frame?

    Thanks,
    Jacob

  2. #2
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    What is the threading on the drive side of the bottom bracket? Is it it normal right handed or left handed?

    A 70 mm bb shell is usually Italian threaded (right handed on both sides) but that would be extremely unlikely on an 80's vintage Japanese bike. They were almost all English threaded, had 68 mm bb shell widths and left-hand threads on the drive side. I'd measure again to be sure.

    Most likely your frame is English threaded and, if it is, getting a new cartridge bb is easy. Actually, even if it is Italian threaded, a new bb is easy to find.

  3. #3
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    >What is the threading on the drive side of the bottom bracket? Is it it normal right handed or left handed?

    It's left hand threaded on the drive side.

    >A 70 mm bb shell is usually Italian threaded (right handed on both sides) but that would be extremely >unlikely on an 80's vintage Japanese bike. They were almost all English threaded, had 68 mm bb shell >widths and left-hand threads on the drive side. I'd measure again to be sure.

    I'll measure again. I'm just using a ruler, so it's possible my eyes are deceiving me (though I've checked it a few times).

    >Most likely your frame is English threaded and, if it is, getting a new cartridge bb is easy. Actually, even if it is Italian threaded, a new bb is easy to find.

    I guess I can also try to dig up a 68mm cartridge for an english threaded frame and see if it fits.

    Thanks for your help.

  4. #4
    coffee bean grinder grinderbob's Avatar
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    italian threading drive side: loosen when you turn your wrench counterclockwise (like if you were to ride the bike backward)
    english threading drive side: loosen when you turn your wrench clockwise (like when you ride the
    bike forward)

    do you see any markings?
    italian: 36 x 24T, 70
    english 1.37 x 24T, 68

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