So lets say I am riding a tri bike with a P2M meter 2x a week, and have an FTP of 280 on this bike/meter
I ride a road bike with a powertap and have a FTP of 305 with this bike (Difference in meter and in position).
To get proper numbers for training should I adjust the TT bike numbers up the percentage of difference, so the IF and TSS would be the same as on the road bike? So as an example if I road my TT bike 1 hour at 280 watts the current IF would be .918, as the FTP setting is 305. Of course the actual IF would be 1.0. So should I adjust the power number on that file by 8.9% so the program has the correct numbers?
I am trying golden cheetah and this change is easy to do.
Have you thrown the Powertap wheel in the bike with the Power2max to see how they actually stack up? If you can’t do that how about a " stomp test" ile. static calibration on each one. I’m very surprised to here the large difference and would want to know which was off that much and fix that first before trying to create a fudge factor.
Of course the actual IF would be 1.0. So should I adjust the power number on that file by 8.9% so the program has the correct numbers?
No.
Assuming your powermeters are reading accurately, your FTP is 305. Just because you can’t hold the same power in the TT position doesn’t give you extra credit for riding that way.
ETA: Look at it this way, if your usual pace for tempo runs is 6:30/mi but heat and humidity causes you to slow down by :15/mile does a 6:45 pace run in 90* heat have the same training effect as a 6:30 run on a cool day? They’re different animals. Endurance training is about teaching your body to turn oxygen and glycogen into muscle contractions. Increasing the difficulty of achieving maximum effort doesn’t change the result. There are plenty of reasons to train in the aero position (or the heat), but it doesn’t have the same effect as more efficient conditions.
I’ve had this same thought and honestly I think your inclination to keep separate FTPs is scientifically and logically defensible. For me, road bike FTP is ~25W more than TT bike FTP. And contrary to what others have said, I observe no physiological difference between 315W on the road bike and 290W on the TT bike. My heart rate is the same. The effort hurts the same. It is all I can do for an hour in both cases.
Anyway, as to whether you should apply these separate use cases to your performance analysis in the form of bike-specific FT values on your rides…I think that’s probably a little ridiculous and anal and totally unhelpful to your ultimate goal of getting faster. But if it’s easy in Golden Cheetah and you really must, yeah it’s the right thing. Just don’t expect it to be a game changer
So lets say I am riding a tri bike with a P2M meter 2x a week, and have an FTP of 280 on this bike/meter
I ride a road bike with a powertap and have a FTP of 305 with this bike (Difference in meter and in position).
To get proper numbers for training should I adjust the TT bike numbers up the percentage of difference, so the IF and TSS would be the same as on the road bike? So as an example if I road my TT bike 1 hour at 280 watts the current IF would be .918, as the FTP setting is 305. Of course the actual IF would be 1.0. So should I adjust the power number on that file by 8.9% so the program has the correct numbers?
I am trying golden cheetah and this change is easy to do.
Have you thrown the Powertap wheel in the bike with the Power2max to see how they actually stack up? If you can’t do that how about a " stomp test" ile. static calibration on each one. I’m very surprised to here the large difference and would want to know which was off that much and fix that first before trying to create a fudge factor.
YMMV,
Hugh
The P2M meter has been tested against two powertaps, a kicker2, and just recently a neo.