I normally set my FTP values (quarterly) by doing a 20 effort up a local hill. Close by, repeatable, etc.
I did one yesterday (10/2) and maintained 290 watts for 20 mins. 290x.95 = 275w FTP
While reviewing my power curve I noticed I had a higher 20 min value from a crit I did on Sunday (9/30) which listed 306w for 20 mins. 306x.95 = 290w FTP
The question now is which # should I use for my FTP? The race driven one or the repeatable effort one?
Thinking back to my most recent test, I'm not sure I could have held 290 watts for another 40 minutes...
Looking forward to your feedback.