10-25% Watts difference Garmin Pedals vs Tacx Flux

I see lots of articles and talk about differences in wattage. In my case, I saw the differences between 10-25% in my workout yesterday.

Tacx Flux that I calibrate via the TACX App.
Garmin Vector 2 Pedals, calibrated via the Garmin Edge 1030.

Is this difference because the Garmin pedals are direct power transfer versus the calculations of the Tacx? Which is the right one? My gut tells me by feel that the higher wattage from the Garmin Pedals is the right one. If I decide to use the Garmin Pedals as the Power Source, can I still use the Tacx for ERG mode on Zwift? Thanks

You can pair your pedals with zwift and your controllable as flux. Then erg mode will work yes.

Normally there is a loss of power the further along the drive train you go. Recently Lionel Sanders https://youtu.be/7G3dts3S76I suggested everyone should have three power sources just so everyone knows what their power is more likely to be.

Have you watched this video? This might not be your model tho. 10 minutes in Shane does a comparison. https://youtu.be/GjmgAwGgI6g

The pedals should read higher, they don’t have the drivetrain losses. But 10-25% sounds too high

Thanks, I saw that Sanders video which is what prompted me to do this test. His numbers seemed pretty similar for all 3 PMs. I’m running 10s Power on the Garmin and I understand the Flux is running 3s Power, not sure if that makes a difference. It was about 10 watts difference at the lower wattages, 110/120 and then widened as I went higher. So, thanks, I will run the Power of the pedals and the Control from the TACX.

In my experience, erg mode doesn’t actually work very well when the power source isn’t the controllable trainer. There’s way too much overshoot.