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  1. #426
    \_(ツ)_/ Ygduf's Avatar
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    TY. now to find a flat road.

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  2. #427
    fuggitivo solitario echappist's Avatar
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    Quote Originally Posted by Ygduf View Post
    Aero "savings" are often listed in grams of drag.

    What is a reasonable amount of "grams of drag" at like 40km/hour for a cDA of 3?
    back of hand mnemonic

    at 30 mph, 50 grams = 5 watts = 0.005 m^2 (CdA) = 0.5 sec/km

    actually it's more like 45 grams, but this is back of the envelope

  3. #428
    gmt Grumpy McTrumpy's Avatar
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    The aerolab data from last night indicated a CdA below .2 for the first time ever. It's not easy to estimate Crr, but I tend to err on the side of too much, choosing a number that is higher than what I measure on my rollers, but not so high that it puts things way out of proportion. CdA worked out to be .1991

    Additionally, I have to estimate transmission efficiency which I tend to keep around .965

    The change? Replacing the long Uvex with a Giro Selector has lowered the CdA by a measurable amount, so far as I can tell. (~.0039)

  4. #429
    Senior Member aaronmcd's Avatar
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    Is it tacky to use electrical tape to hold the aerobar plugs in if they like to come out (clip ons, so no bar end shifters)?

  5. #430
    \_(ツ)_/ Ygduf's Avatar
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    do what you got to do.

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  6. #431
    Senior Member aaronmcd's Avatar
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    I have two random questions.

    While racing a time trial, a hill causes the racer's velocity relative to wind to fall below x, reducing the effect of aerodynamic drag and prompting the racer to optimally leave the aerobars for more power. Solve for x.

    Also, here is a random theoretical question:
    My TT on Sunday is uphill out and downhill back. But say a time trial is the reverse - starting with a descent and finishing with a climb. Should one carry an aero bottle, filled with water and installed with a release valve on the bottom in order to use gravity for an advantage on the first half, and dump the water for the climb?

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