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  1. #1
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    Fixed Gear Conversion: Bottom Bracket Issue

    I'm in the midst of a fixed gear conversion using an older Sears Robeck and Co. frame that was built with a one-piece crank. I pulled the crank off to find that the bottom bracket shell (shown below) has a metal cup for the caged bearings to sit in on each side. I tried loosening them with my hands but they won't budge. I was wondering if it was possible to remove these cups, if there are threads underneath them, and if this shell could be used for a more modern crank/bottom bracket set up.


  2. #2
    Senior Member Retro Grouch's Avatar
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    To remove those cups tap them out from the opposite side with a hammer and an expendable screwdriver.

    To install a 3 piece bottom bracket check out BMX sources. You can either instll a BMX 3 piece crankset or you can press inl an adapter which will allow you to fit a Euro bottom bracket and crankset.

    Either way you'll be spending quite a bit of money on a rusty old frame. A much cheaper solution would be to fit an appropriately sized chainring to your existing 1 piece crankset.

  3. #3
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    Would I be able to slide just any separate chain ring on there or is there something in particular I should be looking for?

    Thanks

  4. #4
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    hmm i restored a vintage fuji and was told to just remove the cage holding the bearings and just free pack the bearings back in with lots and lots of grease

    bike works amazing

  5. #5
    Senior Member RoboIsGod's Avatar
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    if your trying to convert something with a one piece crank, yer wasting yer time. i consider conversions appropriate for mid to low end bikes, but that rule even has its limits.

  6. #6
    cab horn
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    Quote Originally Posted by RoboIsGod View Post
    if your trying to convert something with a one piece crank, yer wasting yer time. i consider conversions appropriate for mid to low end bikes, but that rule even has its limits.
    That doesn't really help, but as mentioned there is an adapter that will take it down to regular BB threading. But then again... how much money is going to be dropped vs worth it is up to the OP to decide. It wouldn't be for me.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  7. #7
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    Don't use a hammer and a screwdriver.

    A soft punch/broom handle/whatever will be much less likely to cause damage if they are in there real good.
    Quote Originally Posted by Santaria View Post
    because physics has more street cred than tarckstars.

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    I'm not planning on putting much money into the bike so I'll be sticking with the one piece crank. I'm having trouble finding a cheap set of wheels so the project has been postponed until I can find a deal I like.

    Robo, why hate on the one piece crank?

  9. #9
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    Quote Originally Posted by Fleacircus View Post
    I'm not planning on putting much money into the bike so I'll be sticking with the one piece crank. I'm having trouble finding a cheap set of wheels so the project has been postponed until I can find a deal I like.

    Robo, why hate on the one piece crank?
    velomine.com for some nice cheap trued wheelsets

  10. #10
    Elitist carleton's Avatar
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    Why?

    Seriously. Save the drama. Use the time you would spend trying to restore/convert this old cheap bike and work for some more money to buy something else. It was likely a cheap bike when it was new. Now it's a rusty OLD cheap bike that will become a rusty, old, cheap, unreliable, untunable bike. Use your time and go rake some yards, wait tables, wash some cars, and save up $200 and buy a new cheap bike from Performance, Bikes Direct, or a used bike in better shape.

    Even if you get the BB and cranks situated, the bigger problem is the rust. Rust is bike cancer. The inside of the tubes are likely more rusted than the outside...and the outside looks pretty bad. One good bump in the road and something will crack.

    Every old bike isn't salvageable. Swallow your pride and throw the bike into the recycle bin. This will probably never become a "sweet fixie" or even a decent bike for that matter.

  11. #11
    Senior Member Retro Grouch's Avatar
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    Quote Originally Posted by Fleacircus View Post
    Would I be able to slide just any separate chain ring on there or is there something in particular I should be looking for?
    You need a chainring for a one piece crank.

    To change it you remove the crankset and unscrew a lockring on the back side of the chainring. (Use a hammer and the same expendable screwdriver.)

    Try not to pay too much attention to the nay-sayers. Think of the project as tuition in the school of bicycle mechanics. The only real trick with a project like this is to limit your out-of-pocket expenditure. The good things you have working for you are that you don't charge yourself labor and you have virtually nothing to lose.

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