Resistance variation when climbing

Hey team, my setup is Tacx Flux S with ATV. All software is current and I have deleted and reinstalled the Zwift app as well.

While on a steady incline I will notice a drop in power and resistance every third or fourth pedal rotation while I am maintaining a steady output. This issue does not happen while riding in the Tacx app only while climbing in Zwift. This obviously gets extremely frustrating.

Has anyone come across this issue before?

Thanks in advance!

Did you calibrate the trainer? It sounds like wheel slipping or a trainer that is overheating.

Thanks for you response! Yep sorry should have mentioned, calibrated in both the Tacx app and in Zwift successfully.

The issue is the same from the start of a Zwift session consistently and not present when climbing in the Tacx App so didn’t think it would be a heat related issue. My trainer is direct drive so no wheel slippage to worry about.

Should also mention it isn’t a complete loss of resistance, if I am doing 3 - 4 watts per kg it might drop down to 1- 2 watts per kg for a second before returning to normal resistance.

I used to have random resistance dropouts on my Saris trainer where my power also went to zero for a few seconds for no apparent reason, then came back.

Typically this symptom is related to the trainer’s Bluetooth signal wafffling. In my case, it was waffling because I had the Garmin Connect app installed on my smartphone. Trainer manufacturers’ apps typically run in the background listening for a Bluetooth signal, and they can steal that signal from Zwift.

Now that you’ve calibrated - please try uninstalling the Tacx app for troubleshooting purposes. Once it’s removed - do the mysterious dropouts go away?