Critical power curve incorrect after TT mode race

Just did my first event in TT mode… used it for a 20-minute power test I needed to do anyway. Bologna course is nearly perfect for this, which is great!

But here’s the weird thing–the critical power curve was WAY off. According to Strava and TrainingPeaks’ power curves my 20-minute CP was 313 watts. But the ride report says 258 watts!

And here’s my time and average power when I crossed the finish line…

I would have to guess that TP, Strava, and Zwift use different algorithms. Looking at the ‘photo’ I can see that your avg was 311 watts (nice job), but I also see that your time was 19:08. And I’m guessing that shortly after the finish line your power dropped to next to nothing (or at least significantly lower) for some period of time, resulting in your average over a full 20 minutes to drop down to the 258 watts in the first shot.

That being said, I have seen other posts indicating that there may be issues with the power curve in Zwift, so I can’t be positive as to what is causing the issue you are seeing.

Not a bad theory Jeffrey. But I kept going to the 20 minute mark since I was doing a 20 minute power test. So I definitely DID average 313w for the 20 minutes. I have no idea where Zwift for their number.

Curiouser and curiouser. Does ZwiftPower provide any additional insight?

ZwiftPower only catches the event data and not the cool down.

Had a thought while Zwifting this morning… checked Strava afterward and I was right!

So, when I did this ride, I actually rode FIRST in Watopia. Just a free ride. I had signed up for a TT event in Bologna, so when that rolled around I clicked and joined that event, and did my 20-minute test there.

Zwift seems to get confused when you do two different “events” in one session… for example, my Zwift Companion activity summary for the Bologna TT shows leader jerseys I won on the Watopia ride. So I thought… maybe the power curve was somehow carried over from the Watopia event too?

Viola! My 20-minute power for the Watopia event is 258w according to Strava. So that’s what happened…

Hope this helps the Zwift wizards fix a bug.

On the topic of wacky looking critical power curves, attached in mine from a TT this morning. Two other sites agree that it should be downward sloping, 1s (414), 5s (391), 15s (359), 30s (352), 1m (341) 5m (288), 10m (277) and 20m (272)! After the TT was over I rode for 2 or 3 more kms at a gentle pace, but I didn’t do a ride before or after this one in the same session.

And this is the other screenshot from the ride report.