Originally Posted by
ctak
Fwiw, you can link your Zwift account to
ZwiftPower, which will extrapolate your 15s, 1m, 5m and 20min "bests" from races you've completed on the platform - expressed both as wkg and watts. Your 20min "best" from any given race determines your race category and will likely resemble what you could achieve during an outdoor 1-hr threshold effort (in my case ~20w lower than results from the non-ramp Zwift ftp test).
I have a ZwiftPower account too. The problem with taking 15s, 1m, 5m etc bests from Zwift events is that they are not really close to my best efforts over those intervals. Actually they are far from it when I compare these against a dedicated Sufferfest 4DP test. If I did interval training based on my ZwiftPower metrics, my power targets would be way too easy, especially VO2 max and above. For example my true 5 min power is over 60W higher than what I've put out in a Zwift event.