FTP Reverse Lookup

The problem with using a 2 minute effort is that you'll be relying largely on your anaerobic work capacity. 20-60 minute efforts will be almost entirely aerobic. In a sense you're measuring two distinct metabolic systems which may not correlate.

There are better ways to estimate FTP : Alex's Cycle Blog: The seven deadly sins

wiredued said:

....Any pros and cons to using this method? How accurate or inaccurate can this be and why?

• Using HR as a relationship to Max HR to validate VO2 Max efforts is questionable. My HR during a 40K TT at FTP is within 10 beats of my Max HR. So for starters I'd question the way you've established VO2 Max pace.
  
• VO2 Max isn't a hard and fast 120% of FTP. Actually VO2 Max can be induced at a range of power's depending on the duration of the effort but either way 120% is a reasonable starting point target for L5 interval intensity as a function of FTP but you can't in general turn that around to deduce FTP. IOW, I've done sets of 5 minute efforts that were very difficult to complete at 115% of FTP and have done 3 minute L5 efforts at ~130% of FTP. They were both L5 efforts for the chosen durations but how would I back out an unknown FTP based on the range of power of those efforts?
  
• As perrygeo mentioned L5 efforts are heavily influenced by AWC which varies substantially between riders. Estimates of metabolic fitness (FTP) based on short efforts are prone to a lot of error due to this alone.
  

So you're basically starting with a swag of VO2 Max and then extrapolating FTP/Tempo with another swag.

But since you're talking about training, not trying to nail down an exact FTP number it doesn't really matter much. Choose the duration of your FTP efforts, ride them as steadily as possible based on speed for the terrain, RPE and HR if you like such that they're hard but not impossible to do the complete set. If your speed drops a lot for the same terrain (and the wind hasn't changed a lot) or you have to back off or quit the intervals then you're going too hard. If they feel easy and you feel you could have gone faster than try the next one at a bit harder pace. In the end you do alls you can do and they self correct pretty fast. There's no real need to extrapolate your target FTP from shorter efforts to get good workouts and to improve.

I'm sure I've said it before but if I had to start all over again with training and didn't have a PM I'd just go with RPE, maybe a stopwatch to time longer hills and just pick intervals of appropriate durations to target specific systems. In the end the only data that really matters is recorded in your legs....

-Dave

daveryanwyoming said:

But since you're talking about training, not trying to nail down an exact FTP number it doesn't really matter much.

Exactly. If your FTP guess turns out to be accurate it would be purely by chance, but how much FTP accuracy is really needed to do decent L4/L3 workouts? (trick question)

Thanks for the replies I need to tweak this already I think it is more like a 125% effort for me... Hey someone added spell checker to this forum😎

daveryanwyoming said:

[I'm sure I've said it before but if I had to start all over again with training and didn't have a PM I'd just go with RPE, maybe a stopwatch to time longer hills and just pick intervals of appropriate durations to target specific systems. In the end the only data that really matters is recorded in your legs....

-Dave

Great point!

It's great to have all the theory and knowledge behind what you decide to do, but there's an art and feel to training that goes hand in hand with the science.