Power data delta between Garmin Fenix 6 and Edge 530

Equipment
1

Strange data delta between my two Garmin devices from a race at the weekend.

I understand where there’d be a delta between my watch and head unit as they use different hardware to measure HR (wrist optical sensor vs HR strap) but they both use the same power source (Quark SRAM AXS Powermeter Spider)

Per the zoomed-in image below, there’s big deviations in the measured power - anyone know why this might be?

I usually just use the Edge 530 but that day I recorded the race on the Fenix also.

Thanks!

image
image1499×595 72.6 KB

image
image1325×409 117 KB

2

As HR strap is more accurate I connected it to Fenix and Garmin Edge so they both use same HR data source. Maybe to try this…

3

It’s not the HR data I have a problem with - it’s the power data

4

I had a few suspicions (look unlikely):

  • power meter “settings” being different on both devices (like for me crank length settings not getting updated?) but that would cause small offset in power (2-5%)… yours is varied and show more of a lag
  • you possibly were recording a riding partner’s power meter somehow?
  • smart recording power saving features on watch/computer or something wonky causing delays/averaging in data entry to the .FIT file? Any weird settings setup?
5

Do you have cadence data that you can look at in parallel? That could tell you if one of the recording devices is missing data from the power meter. Not knowing anything else, and assuming the power meter is sending data at fixed intervals (1Hz?) to both units, it looks like the blue recorder (Edge) is missing not just individual data records, but whole peaks, and just interpolating in between the ones it gets. You could look at the individual records in the two .fit files, for example by converting them to .csv and overlaying them in parallel columns in Excel or Google sheets or similar.