Hello
The result for the race is 405 watts. For the 1 minute power in zwiftpower : 391 watts. Impossible ! (the race is 1km). The calculations are wrong. Very wrong.
In my experience, ZwiftPower can’t process fit files for very short duration events. I doubt it ever will. When we put on a race on the Macaron route, almost every rider had only the live data since they were riding less than 5 min.
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It’s not actually impossible, if race lasts just over a minute and the power at the beginning and the end is very high, but spaced out so that that the best minute does not overlap with both the start and the end.
For example, this fabricated dataset for an 80-second race has a mean power of 405W but a best minute-average of 391W:
For the same reason, you get little apparent anomalies like in this intervals workout I did yesterday, where my 9-minute average power was 245W but my 10-minute average was 262W.
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I haven’t seen Sebastien’s event but this was my experience: https://zwiftpower.com/events.php?zid=4962883
Thank you. I understand but it wasn’t like that. Moreover zwift says 447 watts for 1 minute. But zwiftpower, 391… 
It’s a bug. Zwift must fix it.
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If your event hasn’t processed FIT files due to the short duration, it’s expected that your numbers will be off. ZwiftPower gets almost no development work so I recommend that you expect nothing will change. You can download the FIT file for the activity and upload it to a 3rd party analysis tool if you want to see the real numbers.
What was your event ID?
Thank you.
Here is the event : events.php?zid=5085790
In fact, all the riders had the same problem.
OK I assume it is The Velos Kick event https://zwiftpower.com/events.php?zid=5085790
That event has the same problem I saw with our Macaron race mentioned above. It’s too short for ZwiftPower to get the real data about each rider. You see the little lightning bolts are green. That means no FIT files were processed so the live data is used. ZwiftPower can’t handle it properly. I don’t expect that to change.
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It is not a true bug. You are able to see your power from the start pen until the start line (possibly 3-10 seconds depending on the world/pen/start line)
Zwift power only starts recording power at the start line as the clock begins counting at 00:01 seconds. The time gap will appear in the final results but the power data from those first few seconds will not show in the power average/power.
I’m not sure this is quite true. Checking against intervals.icu, Zwiftpower would have to be missing off the first ~20s of the ride for that to be the case (though that does tally quite closely with the Zwiftpower power figures). The start line is visible from the pens for this route, and, although I wasn’t looking at the clock, I’m quite sure it didn’t take 20s to get there.
Thanks for making me aware of these races, @sebastien2845_hanrar !
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Isn’t this all an old known issue?
ht tps://forums.zwift.com/t/fit-file-doesnt-start-from-beginning-of-zwift-race/595379/7
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It’s probably both issues
Yes, but it really shows up with a race that is just a hair over a minute long.