I've got a query regarding FTP. I've done a few rides with my PT I got a few weeks ago, I haven't undertaken any formalised test to calculate FTP but have incorporated a few hard all out 20 minute sessions in some rides (always at the end of the ride) so I've finished with nothing left. The 20 minute Normalised Power I've gotten from each of these rides has been 247 watts and 246 watts on two occasions with 233 watts on another occasion. This data is taken from the same ride I do each week which is predominately flat with a few short modest uphill slopes and one modest downhill. Going from this and taking say 95% of the NP to estimate FTP would put me in the 228-233 range for FTP.
I've done a few 2x20 sessions on the indoor trainer at 185-190 watts. I haven't tried pushing harder as I hadn't done any formal testing as I haven't had the time.
Here's my query. I've just done the Blayney 2 Bathurst yesterday with a mate, we knocked over the 70ker which I was quite happy with the way the wind played out and never having ridden the course. Now, my NP for the entire ride of 2 hr 22 mins was 201 watts and my NP for 60 minutes was 220 watts. The average watts on my PT display for the entire ride was 191 watts.
What I want to know is does this seem like its sustainable going off my estimated FTP of 228-233 watts? Or have I possible underestimated my FTP ever so slightly? I'm having a hard time comprehending that I can maintain a NP of 201 watts for well over 2 hours and 70 km if my FTP is only 230.
Here's a screenshot from the Power Distribution (the first big step down after the three even bins) takes place at the 220-240 watt bin

