"The 33"-Road Bike Racing - 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

Me too. One has nothing to do with the other.

They probably estimate it based on a W/kg ratio, not a straight Watts function.

lame! My weight goes up and down every time I take a drink or a piss - that doesn't mean my FTP changes.

I just don't believe that the four pounds I pooped this morning will lower my FTP by 7 watts.

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

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.

Relative VO2Max changes with weight.
Note the key word "relative." Absolute VO2max does not change with weight.


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]

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.

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.

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.

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.

If you actually took a four pound dump this morning, you have more urgent concerns.

+1 hear hear...

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.