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  1. #1
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    Theoretical question regarding water bottle weight and time

    I will be riding in a couple of races this year that vary in length between 20 and 60 miles. All are well supported and I could ride with either one or two bottles of water on my bike. I ride mid-pack expert.
    My question is this: If I rode with one 22 oz bottle (approx 1 1/2 pounds) instead of two bottles, how much of an impact would this have on my time?
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  2. #2
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    Not enough to worry about it!

  3. #3
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    If you drop it you are toaster. 2 small bottles gives you a little more security if you are a clutz like me. And it give you more ammo to throw like a green shell in MarioKart.
    Raised in a Chicken-Coop by Chickens

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    AZ
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    Two bottles, use for nutrition on longer races.

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    “Every extra pound you carry above your ideal weight makes you 15-20 seconds slower for each mile of a climb” — May 12′ Issue of Bicycling Magazine

    If well supported, I would go with multiple 'partially filled bottles' as per below.

    I know it may be kind of 'extreme' but it doesn't make sense to me to carve ounces/grams off of a bike and then carry around extra fluid. I believe 12 oz of water weighs .78 lbs or 355 grams

    On another note:
    Even on a relatively short race, I approximate how much I will drink (heat, etc). And then split the difference between two small bottles.

    IOW - For a 1.5 hr CX race I will split one large bottle into two small ones, in case I drop one (never have though) - less fluid in bottle makes it easier to handle, etc. (yes, I know I am carrying an extra water bottle on bike along with an extra cage)
    Last edited by scottz123; 03-02-2013 at 01:24 PM.

  6. #6
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    Great responses; thanks all. That answers it for me.
    The great use of life is to spend it for something that will outlast it.
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    Just train with both bottles. Its not that big of a deal, your over thinking it.

  8. #8
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    Quote Originally Posted by scottz123 View Post
    “Every extra pound you carry above your ideal weight makes you 15-20 seconds slower for each mile of a climb” — May 12′ Issue of Bicycling Magazine
    Every mile of vertical? If so, thats not too much. Ill continue to not sweat it.
    Raised in a Chicken-Coop by Chickens

  9. #9
    LMN
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    One pound at a VAM of 1200 requires about an extra 1.5 watts.
    "The best pace is suicide pace, and today is a good day to die." Steve Prefontaine

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    Quote Originally Posted by LMN View Post
    One pound at a VAM of 1200 requires about an extra 1.5 watts.
    That is beyond my pea-sized brain. What does this mean to a layperson?
    The great use of life is to spend it for something that will outlast it.
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  11. #11
    LMN
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    Quote Originally Posted by insighter View Post
    That is beyond my pea-sized brain. What does this mean to a layperson?
    Sorry, I was rather brief wasn't I.

    VAM is vertical ascent rate per hour. For reference Armstrong at his peak did long climbs at 1700ish. Nowadays grand tour riders climb at 1500ish. A good Cat 1 mountain biker might be able to climb at a VAM of 1200 in a race.

    To figure out the extra power required to climb at a particular VAM with a weight gain use the formula:

    Power = (VAM * mass in KG * 9.8)/3600.

    Interestingly using this formula you can see that faster you climb the more important weight is.
    "The best pace is suicide pace, and today is a good day to die." Steve Prefontaine

  12. #12
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    Quote Originally Posted by LMN View Post
    Sorry, I was rather brief wasn't I.

    VAM is vertical ascent rate per hour. For reference Armstrong at his peak did long climbs at 1700ish. Nowadays grand tour riders climb at 1500ish. A good Cat 1 mountain biker might be able to climb at a VAM of 1200 in a race.

    To figure out the extra power required to climb at a particular VAM with a weight gain use the formula:

    Power = (VAM * mass in KG * 9.8)/3600.

    Interestingly using this formula you can see that faster you climb the more important weight is.
    This is very interesting! So if I am riding in a race and produce 275 watts and weigh 86 kg all kitted up, this would result in a VAM of 1174. If I weigh 87, the VAM goes down to 1160. Do I have this right?
    The great use of life is to spend it for something that will outlast it.
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  13. #13
    LMN
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    Quote Originally Posted by insighter View Post
    This is very interesting! So if I am riding in a race and produce 275 watts and weigh 86 kg all kitted up, this would result in a VAM of 1174. If I weigh 87, the VAM goes down to 1160. Do I have this right?
    Yes you have it right. At least theoretically right.

    The problem with the equation I gave is when you riding gravity isn't the only force you are working against. You have wind resistance, and rolling resistance too. You also have to consider thatk, particularly on a MTB bike, you are alway accelerating and decelerating.

    Wind resistance and rolling resistance can be modeled (and analyticcycling.com does). However, I don't think anybody has a clear grasp on frequency and magnitude of the accelerations in mountain biking. This makes it really hard to accurately predict the effect of a weight increase.
    "The best pace is suicide pace, and today is a good day to die." Steve Prefontaine

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