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  1. #1
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    Reputation: unfluid one's Avatar
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    chainstay length calculations with paragons

    I'm calculating the specs of a custom steel frame using Paragon sliding drops (flanged) and was using this calculator to find the optimal chainstay length using 32x18 or 34x18.
    http://eehouse.org/fixin/formfmu.php...ey=Stay_length

    with a 32x18, it says the CS length is 16.725". Is this calculated under the ideal conditions where the chain is totally straight, or under real life operating scenario where there is some slack? If there's slack, my CS should be calculated around 16.85 or so i think.

    The paragon slider window is 2", but given the 2 bolts that slide inside it, the axle only has 3/4" space to move. I was thinking centering the axle @ 16.75, then setting the sliders so that the shortest/longest CS is [16.5 ---> 17.25], or [16.4 --> 17.15].
    This way, the axle at 16.75 will be in the front half of the slider position so that there's more overlap between the slider and drops.

    Also, if i decide to move up to 34x18, i'd need a position of 16.45 or 16.975. Not sure if I can squeak this gearing into the [16.4 ---> 17.15 position] if i wanted to go short and run 16.45.

    Any thoughts or recommendations on correcting my calculations?

  2. #2
    one chain loop
    Reputation: fishcreek's Avatar
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    your calculation is good, if your frame is for 26" wheels.
    everything sucks but my vacuum cleaner.

  3. #3
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    Oh yeah forgot to mention. 26".
    Do you know if I should expect the CS #s to be a bit shorter than calculated to make up for chain slack?

    Quote Originally Posted by fishcreek
    your calculation is good, if your frame is for 26" wheels.

  4. #4
    one chain loop
    Reputation: fishcreek's Avatar
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    maybe you can start calculating the CS for 34:18 and set that as your minimum, you will still have lots of room for 32:18. and if your chain stretches, you will tug it backward anyways. just careful planning, i know you are in the right track.
    everything sucks but my vacuum cleaner.

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