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  1. #1
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    I picked up a free Motobecane at a garage sale.......

    and am wondering if I can replace the old cotter crank and BB with a modern 68mm square taper. Will the threads match up? The frame indicates the bike was made in France so that makes me think it may have some strange/rare size. This will be my first attempt at working with such an old bike and going in blind, so I appreciate the help.

  2. #2
    people's champ marley mission's Avatar
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    free motobecane! suhweet! stay cottered - classic look - just use the right tool to remove the pins
    Kleins, Kleins...everywhere there's Kleins

  3. #3
    Senior Member mparker326's Avatar
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    pics?

  4. #4
    Senior Member wahoonc's Avatar
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    Yes you can...if you find the correct size bottom bracket cups. I did it way back in 1978. You most likely will have either a Swiss or French threaded BB. FWIW I used Campy cups in mine, because that was what was available at the time.

    Aaron
    Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(

    ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.

    "Cycling should be a way of life, not a hobby.
    RIDE, YOU FOOL, RIDE!"
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    "Steel: nearly a thousand years of metallurgical development
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    Which one would you rather have under your butt at 30mph?"
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  5. #5
    Senior Member cycleheimer's Avatar
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    JensonUSA seems to have a good supply of BB cartridges when you're ready to order...

    http://www.jensonusa.com/store/sub/1...+Brackets.aspx
    Bike-A-Holic

  6. #6
    Senior Member auchencrow's Avatar
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    Quote Originally Posted by marley mission View Post
    free motobecane! suhweet! stay cottered - classic look - just use the right tool to remove the pins
    +1

    Unless there is a problem with the crank, changing to cotterless will degrade the looks and durability of the crank in exchange for a minor weight reduction and some grief/expense in finding a suitable spindle &/cups.

    (PS- Pics or it didn't happen!)
    - Auchen

  7. #7
    Senior Member ScottNotBombs's Avatar
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    If you decide to upgrade, you may be able find a spindle the right length and just replace that. If you have to buy a bottom bracket and crankset, the cost isn't worth it.
    I'm just a kid who gets in trouble sometimes

  8. #8
    Novist senior member tolfan's Avatar
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    I have done this a few times and I always used the cups that came with the bike, never had any problem.
    There are some things a man needs to believe in wether they're true or not;

  9. #9
    Senior Member michael k's Avatar
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    Iv;e done it twice.

    The '75 came with english threading




    This HAD swiss threading.Retapped to english.


  10. #10
    Is a real super guy. Henry III's Avatar
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    I don't know what's the hassle with cottered cranks? Loosen up the bolt but leave it on enough to cover up the threads(if you want to save them or sell them) and a few taps with a hammer or mallet. No need to deliver death blows just a few love taps and they always come right out.

  11. #11
    Mike Coop500's Avatar
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    Quote Originally Posted by marley mission View Post
    free motobecane! suhweet! stay cottered - classic look - just use the right tool to remove the pins
    Agreed, I'd be happy to just to get one free. There is a nice one for sale locally for $150 and I thought that was good LOL.
    1994 Specialized Rockhopper Fs
    "Twenty years from now, you will be more disappointed by the things that you didn't do than by the ones you did do"- Mark Twain

  12. #12
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    After this discussion now I'm thinking maybe just clean it up as best I can and leave it as original as possible. New chain, cables/housing, brake pads, tires/tubes. The frame has some rust on the stays and rear wheel will need to be replaced, but I just happen to have one that will work. I'll have to check ebay and see if these are worth the fixing.....the frame is too large for me.

  13. #13
    Senior Member wahoonc's Avatar
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    Quote Originally Posted by Henry III View Post
    I don't know what's the hassle with cottered cranks? Loosen up the bolt but leave it on enough to cover up the threads(if you want to save them or sell them) and a few taps with a hammer or mallet. No need to deliver death blows just a few love taps and they always come right out.
    You obviously HAVE NOT come across the pseudo welded cotters yet...

    I have had to drill a couple out over the years, and that was after trying a cotter press and a large hammer. Not all cotters are going to gently tap out.

    Aaron
    Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(

    ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.

    "Cycling should be a way of life, not a hobby.
    RIDE, YOU FOOL, RIDE!"
    _Nicodemus

    "Steel: nearly a thousand years of metallurgical development
    Aluminum: barely a hundred
    Which one would you rather have under your butt at 30mph?"
    _krazygluon

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