I did a workout and recorded it in Zwift and on my Garmin Edge. Zwift tracked the KICKR and the Garmin the PM data. As you can see, the XRRS is completely different.
Aside from the obvious difference in set 2, the XSSR is very different in set 1 and 3, but in a different way.
Any idea why this could be?
Turn off power smoothing on KICKR and if you really want a SMART workout to play as intended use EBC.
Thanks @ridgerider2 .
I wsn’t wanting a Smart workout, I was leading a group of athletes so it wouldn’t be effective.
I don’t understand how turning off smoothing would have the response seen in the two traces. Power on any interval are equal between the two data sources.
I’ll write it off to a random quirk of Xert and Garmin not playing nice. Good thin I had both, the Garmin would have given a very false model of the workout response.
I think it’s simply different powermeters report different power, even if calibrated. Why not use you powermeter for both garmin and Xert?
The other thing, probably second order, is that if you have the activity twice, your signature changes a bit from activity to activity (due to strain and any BT) so numbers will be a bit different (shouldn’t be huge though)
On previous tests, the PM and KICKR reported power within less than 1% difference across a range. I generally use the PM as power source, but on this occasion.
Regardless, the amount of reduction in HIE is way beyond any power difference, which was negligible during these intervals. Also, if I delete the Zwift file, the file looks the same.
Smoothing would have no effect modelled draw HIE either, as smoothing is the rendering of the data not a modification of the underlying data.
I had this case before and it’s just that my fitness signature was updated between the first and second activity so the second activity (it was the same as the first) looks different as it was placed after a breakthrough
Actually a SMART workout performed as a group session would be more effective but that’s another story. 
@hugoyave’s answer sounds likely with a pre-adjustment chart shown in image #1 and image #2 with the updated signature applied.
Image #2 is still “fake news” though. You have to disable power smoothing in the Wahoo app to resolve that.
