Time drift with duel recording

I have uploaded a .fit file in ZwiftPower for analysis and found that the .fit file has a time drift. I can line up the start of the effort, but the drift results in a 15 sec delay by the end of the effort. Any ideas on how to fix this?


You can do it in the analysis tool in Zwiftpower directly - with Time shift and crop.
I am on my mobile phone now, hope the screenshot helps.


Thank you for the reply. Unfortunately that is not exactly the problem. It is not that the time is offset, but that the secondary power file is actually 15 sec longer for the effort for the same race. I tried to put in some screen shots (hope they show)

full ride:

first part (data is lined up):

end part (data is not off):

That is really weird, never seen something like that.
Which devices and software are you using?
Was it a Zwift event perhaps (some users reported time issues when riding big events)?

Sorry, no other idea…

Thanks. I’m glad that I am not the only one who thinks this is weird.

The Kickr is a v5 that is connected to an Apple TV. The Quarq is a DZero that is connected to a Garmin 520. The heart rate data shows the same time drift dispite the source for both files is the same (Garmin HR strap), so it suggests that it is due to the recording device and not the power source.

A friend recommended changing the data capture setting on the Garmin 520 from “smart” recording to “1 sec” recording. I will see if that fixes the discrepancy when I ride tomorrow.


That is an idea - my Polar M460 pauses recording when I stop IRL (traffic lights) - but only when recording with GPS?!?
Could it be anything similar?

Unfortunately changing the data recording setting on the garmin did not fix the problem. I did isolate the issue to the recording devices. In the first screen shot, the garmin is capturing the quarq power and that file time is longer. In the second shot, the garmin is capturing the kickr power and again that file time is longer.