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  1. #1
    Carpe Diem bdcheung's Avatar
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    Monod, CP, and Weight

    How does weight factor in to calculating estimated CP's? I noticed that as I adjust my race-weight downward, CP60 also goes down (significantly).

    /confused
    "When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
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    Resident Alien Racer Ex's Avatar
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    Me too. One has nothing to do with the other.

  3. #3
    Burning Matches. ElJamoquio's Avatar
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    They probably estimate it based on a W/kg ratio, not a straight Watts function.
    Reacting is mind candy; it requires no thought. Thinking is tedious.

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    Carpe Diem bdcheung's Avatar
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    lame! My weight goes up and down every time I take a drink or a piss - that doesn't mean my FTP changes.
    "When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
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  5. #5
    Carpe Diem bdcheung's Avatar
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    I just don't believe that the four pounds I pooped this morning will lower my FTP by 7 watts.
    "When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
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  6. #6
    Senior Member Bullseye's Avatar
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    Quote Originally Posted by bdcheung View Post
    lame! My weight goes up and down every time I take a drink or a piss - that doesn't mean my FTP changes.
    Right, and that's why this is just an estimate.

    Weight is a very tricky thing to nail down - the amount of food or water in your system at any given time fluctuates a lot. Sometimes during my intense training days, my weight will fluctuate +- 7 pounds from my 165 base.

    If you measure your weight fairly often, you can see the noise and thus correct for it somewhat.

    -bullseye

  7. #7
    Senior Member Coyote2's Avatar
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    Quote Originally Posted by bdcheung View Post
    I just don't believe that the four pounds I pooped this morning will lower my FTP by 7 watts.
    If you actually took a four pound dump this morning, you have more urgent concerns.

  8. #8
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    Quote Originally Posted by NoRacer View Post
    Relative VO2Max changes with weight.
    Note the key word "relative." Absolute VO2max does not change with weight.

    Quote Originally Posted by NoRacer View Post
    Lactate Threshold is some percentage of VO2Max.
    It's also some percentage of the distance from the Sun to the Moon. Just because two numbers can be divided does not mean they are directly proportional and move in lock step. LT can easily be moved relative to VO2max, and I believe VO2max can move without a corresponding change in LT.

    As to the role of weight. look at the units. FTP and LT are both measured in units of power,, e.g., Watts, weight does not enter into it.[/QUOTE]

  9. #9
    Carpe Diem bdcheung's Avatar
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    Quote Originally Posted by asgelle View Post
    As to the role of weight. look at the units. FTP and LT are both measured in units of power,, e.g., Watts, weight does not enter into it.
    Hence my confusion on why the projected CP60 changes (rather drastically) with weight.
    "When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
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  10. #10
    Making a kilometer blurry waterrockets's Avatar
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    Using MonodCP.xls, I can reduce my weight by 100 lbs and my FTP remains constant. CP also remains constant.

    W/kg changes of course.

  11. #11
    Carpe Diem bdcheung's Avatar
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    Quote Originally Posted by waterrockets View Post
    Using MonodCP.xls, I can reduce my weight by 100 lbs and my FTP remains constant. CP also remains constant.

    W/kg changes of course.
    I was using the other spreadsheet - the one where you can enter 4 tested values. I guess that answers the question of which is more reliable.
    "When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
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  12. #12
    Making a kilometer blurry waterrockets's Avatar
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    Interesting. Yeah, they must be making some assumptions about how much power you lose when you lose weight. That's pretty crazy, but I don't know enough about the systems involved to discredit them.

  13. #13
    Senior Member Snicklefritz's Avatar
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    Quote Originally Posted by Coyote2 View Post
    If you actually took a four pound dump this morning, you have more urgent concerns.
    +1 hear hear...

  14. #14
    Resident Alien Racer Ex's Avatar
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    If the sheet you're using links critical power numbers to weight it's worthless. A backpack of lead does not change your FTP or CP.

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