Murph, I have been debating the same thing. I have been using power on a tacx Vortex. I have my P1's getting delivered to my house on Saturday.
luckily the time works pretty well for me as I am just finishing week 2 of the Sustained power build and week 4 has a programmed FTP test. but between now and then I plan to keep tabs on the difference between the two powers so that I have a frame of reference when I go to retest and adjust things to use the P1 power instead of the vortex.
my other thought was to do a ride and hold FTP as stated by the vortex and take note of what the power was on my P1's and then just adjust from there. I dont think it makes a big difference which way you go, the consistency is whats important
luckily the time works pretty well for me as I am just finishing week 2 of the Sustained power build and week 4 has a programmed FTP test. but between now and then I plan to keep tabs on the difference between the two powers so that I have a frame of reference when I go to retest and adjust things to use the P1 power instead of the vortex.
my other thought was to do a ride and hold FTP as stated by the vortex and take note of what the power was on my P1's and then just adjust from there. I dont think it makes a big difference which way you go, the consistency is whats important