Just did a Ramp Test yesterday and it say’s my new FTP is about 279W (last was 267W 6 weeks ago) … so i would say my realistic FTP what i can do for an hour is about 270W to maximal 275W now.
BUT what suprises me, in this Ramp Test my W’bal went under zero (to -2.4kJ).
My setting so far was 20.5kJ, so i reached a W’bal from 22.9kJ am i right? Intervals.icu says “Max W’bal depletion is 22.1 kJ” at this ride.
Just for interest…
When i look on my Power Curve with model “eCP: Single max effort and Morton’s 3P” i get an eCP 267W and W’bal 22.56kJ (what is really close and realistic).
If i use the model “eFTP: Single max effort and Morton’s 3P” i get an eFTP 273W and W’bal 21.21kJ (so all really close together).
So my question is… how do i know if now maybe my FTP-setting is incorrect (to low) or my W’bal grow bigger? 
Hi,
One thing that I’ve learned is that those numbers are all in a big range of at least + - 5% so need to worry.
Second is that usually is not possible to hold the FTP number of a ramp test for one hour.
You should try.
Regards
To know if your FTP is correct, there is only one way and that is to do the real FTP test and ride for an hour. Good luck on that. The controversy then is that if your FTP is correct, your W’ will almost not change because you’re not riding above FTP.
I think it’s better to ballpark W’ with shorter intervals way above FTP. W’ is not intended to give good results around FTP. It is a tool to judge your anaerobic capacity.
With your new FTP setting, do some VO2max intervals untill exhausted and check if your W’ is about 0 at the time of failure. That’s probably the closest you will get.
And as @Gato_Felix says, those numbers will always be approximative because your FTP changes continuously following your state of balance. There will always be days with “Good” or “Bad” legs.
W’ is a tool to help you judge your anaerobic performance but it is far from perfect.
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