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Pedals threading. What am I missing?

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  • Pedals threading. What am I missing?

    The more I think about it, the less the physics makes sense. Yet I can't be right while billions of people over a hundred years have all been wrong. Right?

    This is about the threading orientation on both (obviously) the pedal and the crank being reversed between the sides.
    If the pedal bearings were perfect - with absolutely zero friction - it wouldn't make any difference. The whole idea is that if there is some friction, then the rotation (when pedaling forward) tends to tighten the pedals, not loosen them.
    This is what puzzles me. The threading on the right side has the regular orientation: clockwise to screw, counterclockwise to unscrew (the other way around on the left side). But, when pedaling forward, the right pedal in regard to its crank rotates counterclockwise. Same reasoning for the left side, only in reverse. In other words, the pedals' rotations when pedaling forward tend to make the pedals come loose!

    So, what part of the problem right under my nose am I not seing?
    Or is it one hell of a long lasting conspiracy by the Loctite people?
    Last edited by Garp; 2019-04-06, 03:27 AM.

  • #2
    https://blog.everydayscientist.com/?p=2655

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    • #3
      Thank you for the explanation, JimT. This had been bugging me for a while.

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      • #4
        An easy, and classic, demonstration is to wrap your hand around one end of a pencil and move the other end around in a circle. Circle it forward, and watch it rotate backward at the same time - voila!

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