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  1. #1
    Who farted? Ka_Jun's Avatar
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    Sigma 1200 wheel size chart question

    http://www.sigmasport.com/en/allgeme...C_1200_nat.pdf

    I'm running 26x1.95 tires.

    26x1.9 - 1298
    26x2.0 - 1313

    so 26x1.95 should be 1305.5? Right? 1200 doesn't do fractions/decimal, so is it better to round up, or down?

  2. #2
    Senior Member MNBikeguy's Avatar
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    Unless you keep your tires digitally inflated at a constant pressure within a tenth, it doesn't matter.
    "I thought of that while riding my bike."
    - Albert Einstein on the theory of relativity

  3. #3
    Who farted? Ka_Jun's Avatar
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    You would think, but I was running 26x1.5s and the same one way run came up as anywhere from 3.53 to 3.55 miles.

    Using 1306, same run came out as 3.68 miles this morning.

  4. #4
    Senior Member demoncyclist's Avatar
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    The only truly accurate way is to do a rollout. Put something on the tire of the wheel with the sensor that will transfer a mark to the ground. Then ride the bike with the tires inflated to your preferred inflation pressure. Measure the distance between two marks, and that is your number (in mm).
    DEMON

    Satanic Mechanic
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    2011 Lynskey Sportive (Shimano Ultegra 10s)
    1988 Cannondale SM400 (Suntour XC-M 7s)

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