How accurate is it? 20min power x .95??

Discussion in 'Power Training' started by BlueJersey, Aug 13, 2006.

  1. BlueJersey

    BlueJersey New Member

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    On this past Saturday I did my usual local race. I wasn't feeling so great but my power data proved the otherwise. I basically broke all of my 1 minute, 5 minutes, 20 minutes, and 60 minutes power records. I launched 2 massive attacks on a hill (50sec) and followed by breakaway effort at 110% FTP.

    My 20 minutes power at NP came out to be 291w. Current FTP is 240w to 250w and last tested was around late May. If I use the 20 minutes power x .95 formula, would it be realistic to say that my new FTP is 276w???
     
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  2. gvanwagner

    gvanwagner New Member

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    Depending on the power curve lots of anaerobic efforts can cause NP to throw out a few dingers on shorter durations because it assumes little important AWC contribution.

    Personally, the lowest 20 min TT effort I've done was 1.10xFTP. I'd bet that doesn't apply to most. But still, I never really liked the 20X.95-it's worse than the
    feel-o-meter.

    Do some Z4 intervals when your feeling good, after one effort you know... either doing good or groveling.
     
  3. Squint

    Squint New Member

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    Don't use NP?

    What was your 20 min AP during the race?


     
  4. Spunout

    Spunout New Member

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    If you haven't tested since May, test again.

    I don't know what everyone else's experiences are, but I test better in a focussed workout than in racing. Races are longer and usually have shorter efforts and so much more of them.

    Testing might be best if you perform them in a more controlled manner. That said, I bet you'll exceed or match 291 (what was AP?) and you should increase your FTP.
     
  5. RapDaddyo

    RapDaddyo Active Member

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    It sounds as though your 20min effort was dominated by AC efforts, as should be evidenced by a large gap between AP and NP. I think the .95x20MP=FTP is more reliable for fairly constant power efforts and even then it doesn't work for everybody due to the strong influence of AWC on 20min efforts. For example, my FTP tends to be ~92% of my 20MP (constant power effort).
     
  6. BlueJersey

    BlueJersey New Member

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    About 205w. :D


     
  7. SolarEnergy

    SolarEnergy New Member

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    Sure. It may as well be. Keep pushing mate, and congratulations for those records that you broke.

    It's hard to tell what this 291np is worth, after all we don't know when it came in the race, what was the fatigue level then, it's part of an overall 60min of what (part of an overall 60min of 240-250 maybe?).

    Maybe the question you want to ask yourself is : If during that day, you would have had to ride only 1x20min, with other riders around you for motivation, do you think you would have done 290w at more constant power?

    Anyway, these attacks, your 1,5,20,60min records, it's all good. :cool:
     
  8. Foothills Rider

    Foothills Rider New Member

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    When determining baselines, is it preferable to do them as stand-alone measurements, or is it preferable to download into CP and find your peak 1, 6, 12, 20 minute efforts? Is one method more valid than the other?

    Thanks!

    Bill



     
  9. RapDaddyo

    RapDaddyo Active Member

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    The problem with cherry picking MMP numbers from CP is that they represent different types of efforts and different levels of motivation. So, it's difficult to compare efforts of one duration with another (e.g., 6min vs. 20min) and with efforts of the same duration at two points in time (e.g., 20min efforts on 7/1 and 8/1). I prefer to ride all of my performance benchmarks in the same way, as constant power efforts on courses with a relatively constant grade (flat or upgrade). I know that I can always ride a variable power effort at an NP equal to a constant power AP (but not necessarily vice versa). This gives me comparability both horizontally (across durations) and vertically (across time).
     
  10. Foothills Rider

    Foothills Rider New Member

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    That makes perfect sense...Set courses and distances enhance standardization for comparison purposes.

    Many thanks!!

    Bill


     
  11. rjjasick

    rjjasick New Member

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    RappDaddyo, can you clarify that last comment? I'm very new to the Power stuff and haven't even read through Coggin's book all the way yet. But are you saying that taking the values you'd get from a race aren't as accurate as you'd get from a stand alone test? The reason I ask is it seems I can ride longer above my HR LT on a race or group ride than in testing. I'd assume the same for my FTP which I haven't yet figured out. I seem to be able to suffer much higher when I have to hang on then when I have to make myself ride that hard. I know I need to get my head to think that I can ride faster than it thinks I can ride, because physically it seems I can.
     
  12. RapDaddyo

    RapDaddyo Active Member

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    Well, there are basically three variables that will determine your max power for a given duration. One is clearly motivation, which is what you alluded to in your comment about being able to sustain a higher intensity of effort in a race or group ride than in testing. That is common. Two is rest. If you do a 20min max power effort the day after 3x20 @ 100%FT, you are likely to be at least 5-10 watts lower than if you were well rested, maybe more. Three is whether the ride is at a relatively constant power or highly variable power. Some people get higher NPs with highly variable power rides than they can sustain with constant power rides of the same duration. For performance testing purposes, I find it best to do the efforts in the same way and with a similar amount of rest. Hopefully, my motivation is similar although that's the toughest variable to control (somedays I feel charged up and other days I feel a little flat). When you randomly pick values off of your MMP/duration curve, you are likely picking values that represent huge differences in all three variables. I prefer to do performance tests as constant power efforts on courses with a slight upgrade. I do the same (3) durations each time and with (as close as I can manage) the same motivation. So, I have a lot of consistency from test to test. Then, I use the Critical Power Curve to estimate my max power at any duration.
     
  13. sugaken

    sugaken New Member

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    How accurate do you think the estimation by the Critical Power Curve is? I'm particularly interested in its accuracy in longer durations (>60min).

    Thanks,
     
  14. RapDaddyo

    RapDaddyo Active Member

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    I think it's pretty good, depending on the durations of the input data. I am likewise interested in longer durations (e.g., 120mins). This is in part why I use a 30min duration in my 3 data points (3m, 8m, 30m). You want a performance test that eliminates most of the influence of AWC. Even with this approach, I think the most likely error is to slightly overestimate MP at longer durations.
     
  15. otb4evr

    otb4evr New Member

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    I would be more inclined to look at the 60 min NP...

    What was that number BTW?

    Jim
     
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