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  1. #1
    Senior Member
    Join Date
    May 2007
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    Madison, WI
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    Tease Fixed Gear, Schwinn World Traveler 72, 60's Hawthorne
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    J.I.S vs ISO headset, what's the difference

    Ok, so I'm trying to figure out what is the difference between the JLS and ISO headsets. I don't really get it?
    So a 1inch tube is a 1 inch tube right? (obviously not). So each type of headset has cups that are the same but the crown fork race is different? The reason why I ask is that I went to my ibs a few months ago and bought a new headset (cheap one), the cups fit in fine (required the homemade cuppress of course), but the race was too small. They filed down an edge on my fork and got the race to stick on. I've been riding my bike for 3 months and it's ok, but not great (obviously I bought the 20.00 headset). But I've been feeling the need to upgrade the headset and the fork (if needed-I should be able to get a used steel/alum fork from an LBS (different LBS of course) ) but now I'm just lost on the sizing. I have a one inch threaded headset on there now that is not the JIS size (probably should have been given that my bike is definitely from the late 70 and was definitely bottom market it's brand was the tease, but I still love it). I wanted something with sealed bearing (I was thinking a dura ace or any suggestions?), but I need to know what size I need, what types of fork, etc... and inorder to do that I need to figure out the difference between JLS and ISO and previous posts just don't sink into my head...so how you you explain this difference to your grandmother or 5 year old brother (me )? Thanks for the help, I know this is a lame question, but I'm sure you all know what is going on here! I don't!

    Brian

  2. #2
    Senior Member
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    For some reason I originally thought it was JLS not JIS so when I write JLS I mean JIS

  3. #3
    Low car diet JiveTurkey's Avatar
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    Aug 2007
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    Corvallis, OR, USA
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    2006 Windsor Dover w/105, 2007 GT Avalanche w/XT, 1995 Trek 820 setup for touring, 201? Yeah single-speed folder, 199? Huffy tandem.
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    Quote Originally Posted by slopvehicle View Post
    Not wearing a helmet makes me more aware of my surroundings. I find myself anticipating the hardness of concrete 50 or 100 feet in front of me, it's almost a zen-like connection between my face and the pavement.

  4. #4
    Low car diet JiveTurkey's Avatar
    Join Date
    Aug 2007
    Location
    Corvallis, OR, USA
    My Bikes
    2006 Windsor Dover w/105, 2007 GT Avalanche w/XT, 1995 Trek 820 setup for touring, 201? Yeah single-speed folder, 199? Huffy tandem.
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    Sounds like you originally had a JIS setup. The new headset is ISO. JIS and ISO frame cup diameters are slightly different, but can usually be interchanged. The JIS crown race is slightly larger, so that's why the JIS fork had to be filed to accommodate the smaller ISO crown race.

    Since the fork has been modified for ISO, a new sealed ISO headset should be able to go on w/out problems.
    Quote Originally Posted by slopvehicle View Post
    Not wearing a helmet makes me more aware of my surroundings. I find myself anticipating the hardness of concrete 50 or 100 feet in front of me, it's almost a zen-like connection between my face and the pavement.

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