Missing cadence data during uphills. Tacx Vortex


I have a Tacx Vortex Smart and today I rode my first 30km in Zwift.

I use Zwift on PC, my Vortex drivers are up to date and it`s connected by Bluetooth via iOS app, the trainer is calibrated.

The Problem:

On uphills my Zwift cadence is messed up - it drops to 0, but in reality I`m spinning hard. Then the oncsreen cadence is rising, the power stays in the same level, the avatar speed is at minimum.

After some time my power output froze on 194w and the trainer stopped adding any resistance. You can see this data anomaly here - https://www.strava.com/activities/1266399002/analysis.

Is it some kind of strange speed/cadence Zwift algorithms or did I miss smth during the installation?


Sounds like interference with your Bluetooth.  Make sure there are no other devices around that could be interfering.  The fact you lost cadence and also resistance points to it being more than an anomaly with the trainer.

I’m slightly confused that you say you are using Zwift on your PC but you are connecting via Bluetooth on iOS.  In my opinion connecting via Ant+ is very stable compared to Bluetooth.

And also the cadence figures offered by the Vortex can be a little estimated incorrectly.  So much so I’ve now fitted a dedicated cadence sensor instead,