puzzling cottered crank
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  1. #1
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    puzzling cottered crank

    I encountered a crank today where the non drive side is held on with a cotter and the drive side is fixed to the bottom bracket axle. The shell is not threaded and uses pressed in cups of smaller diameter than a schwinn. The cups appear to be non removable. All the preload on the bearings is accomplished via adjusting outer races threaded onto the crank arm.

    the owner damaged the BB axle, i'd like to find a square taper adapter but they appear to be for the larger schwinn and i don't see any cranks like this on ebay.

    The bike is a Futurematic 3 speed made in Austria.

  2. #2
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    picture?
    Too old to ride plastic

  3. #3
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    Quote Originally Posted by jroden View Post
    I encountered a crank today where the non drive side is held on with a cotter and the drive side is fixed to the bottom bracket axle. The shell is not threaded and uses pressed in cups of smaller diameter than a schwinn. The cups appear to be non removable. All the preload on the bearings is accomplished via adjusting outer races threaded onto the crank arm.

    the owner damaged the BB axle, i'd like to find a square taper adapter but they appear to be for the larger schwinn and i don't see any cranks like this on ebay.

    The bike is a Futurematic 3 speed made in Austria.
    The joys of proprietary systems. Just as much a pain today as in the ancient history when this bike was made.

  4. #4
    Russian Troll Farmer
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    Chances are that if it's Austrian, it's made by Puch. If there is a forum for classic Puch bikes somewhere, this setup might be known.
    "L'enfer, c'est les autres"

  5. #5
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    Quote Originally Posted by No Time Toulouse View Post
    Chances are that if it's Austrian, it's made by Puch. If there is a forum for classic Puch bikes somewhere, this setup might be known.
    Thanks, from lookin at the "touring" bikes it appears to be a Puch. Still no luck on finding that oddball crank

  6. #6
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    Quote Originally Posted by No Time Toulouse View Post
    Chances are that if it's Austrian, it's made by Puch. If there is a forum for classic Puch bikes somewhere, this setup might be known.
    Or Austro-Daimler - I think Puch made their bikes at some time.

  7. #7
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    Quote Originally Posted by ogre View Post
    Or Austro-Daimler - I think Puch made their bikes at some time.
    I believe that they are one in the same today.
    "L'enfer, c'est les autres"

  8. #8
    wim
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    I'm pretty sure the bike has what's known as a Thompson bottom bracket. The chain wheel, drive-side crank and axle on these Thompson units are often swaged together to form one piece, like the one in the video at the link seems to be. The German term for such a bottom bracket is Thompson-Innenlager in case you need to search for a European vendor. These Thompson bottom brackets were popular for a long time on many brands of lower-end European utility bikes, so it's not a proprietary design.

    https://www.youtube.com/watch?v=U3NFZ_zD5as

    For what it's worth: An earlier version of the Thompson bottom bracket had the non-drive side crank arm press-fitted onto the axle taper. There was no cotter. The only way to get that crank arm off was with a puller, or by driving it off the axle with repeated blows from a large hammer.

    https://www.youtube.com/watch?v=tQsIXv4JUGA
    Last edited by wim; 4 Weeks Ago at 08:37 AM.

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