Hi there
I was wondering if there is a specific reason for which you take 100% of the average watts over the 20’ part of the FF test as the FTP and not the (what i thought) standard 95% of it like for typical CP5/CP20 tests?
It’s not a big deal to go with your own sessions as they are consistent with this specific measurement of FTP but to actually proxy the “true FTP” like max AP attainable for 1h or to compute TSS etc. one should keep going with 95ish% of it right?
Thanks and best regards
The idea is that the 95% is based on a session that you do fresh.
By the time you reach the FF 20 minutes interval, you’ve exhausted some of your energy levels already on the sprints and 5 minute effort and therefore the 20 minutes is 100% of your FTP
Hi @Xtopher
Two answers to your question;
The first (assuming you’ve not done your FF yet) - Do it and you’ll see why 
The second - “The 5 minute test saps your Anaerobic contribution and that effort helps give you a true FTP.” From https://support.thesufferfest.com/hc/en-us/articles/360015060279-How-to-Pace-the-Full-Frontal-4DP-Fitness-Test
If you pace your FF well the FTP to go with is what you get, rather than adjusting it. Your TSS will be correct.
Cheers and Good Luck
Thanks to both of u for your answers.
Actually i always thought that it was less then 95% (like 92/93%) if doing a CP(20) while 95% if after a CP(5) (note i always found that the 2 percentage points are not much compared to the awfulness of the 20’ AFTER the 5’).
Of course it depends on personal abilities…
From my own perception i have done FF several times without cheating (= really pushing at max effort for the 5’) and as ugly it was, I am not sure i could hold that pace for 1h without the 5’ before… only one way to check huh? 
Let us know how it goes …
My first tongue-in-cheek answer was more a reflection of how fresh my last FF was. Yesterday. BRUTAL!
No worry, i had understood it right!!
I remember first time i have done it this moment of perplexity when you are told to go down the trainer and walk for a while… and of course this moment when you want to die while having hardly completed 8 minutes out of 20 
No matter whether it is a step test, Half Monty, a typical 20 minute effort, or the Full Frontal, I know for me there is no way I can hold the resulting number for 60 minutes. In fact I could knock 10% off the results and that would be much more accurate for 60 minutes. The test results are great for setting your training levels (the whole point)- not so great for bragging to friends who can then check Strava and call you out.