Threshold power is consistently overestimated by progression

It seems that the Xert algorithm consistently overestimates my “FTP.” I recently did a HR-based aerobic threshold test and got a number only 75% of my Xert one-hour power. I believe that test may have underestimated this, but looking back at my performance on hill-climb races, I am certain that my Xert-extracted threshold of 286 W is utterly incorrect. In fact, if I go to my most recent hill climb even in which I properly blew up, I am able to extract a drastically different fitness signature that gives me a more reasonable threshold of ~250 W, while keeping my short-time power curve rather similar.

I have tried to take this corrected set of parameters and plug them back into my initial values and let the algorithm chug through my activities, but it keeps coming back to this absurd ~280 W FTP. In fact, now the algorithm is rapidly dropping my max power in the off season (I can’t manage to hit max power on the trainer because the ramping of resistance does unrealistic things to my cadence), but it keeps growing my FTP back to this unreasonable value.

Should I just ignore all of my past fitness signature parameters and save my current numbers? Then what? every couple months I have to identify a good activity to use as a metric to extract reliable values?

Check your best 10 minute power on Dec 31st. Given your HIE is already very, very high It would be near impossible for you to have an TP below 280 and perform that 10 minute effort. If that effort is an anomaly, flag the activity and things will come back down for you (but not by much unfortunately). You have a lot of big gaps in your data which isn’t great. I’d suggest you remove everything before July of last year and run a progression recalc if you’re unhappy with the numbers. You don’t have many great, deep breakthrough efforts so next time you do an all-out effort and you don’t get a breakthrough, send a note to support and we can see if your numbers are overestimated.