TACX Vortex/ Cadence & Resistance

I am having a problem with my trainer having not been in zwift for 3 or so weeks- I have downloaded all the Zwift & TACX patches etc. The first thing i notice is that my cadence is all over the place- I hit 90 rpm and it feels right but the readings then jump to 130 rpm without me changing. The next thing i notice, obviously connected, is that I will get into a sprint on a segment- get into a higher gear and get a constant increased power down with a lower cadence, it will hold for about 15 seconds and then the trainer releases any traction and i am left spinning against no resistance. Its only when I slow down my cadence that resistance comes back. Very frustrating, anyone any ideas??? Grateful for any help… Thank you in advance.

Hi Charlie,

The Tacx Vortex uses estimated cadence and just isn’t very accurate. I’m surprised it’s coming up in Zwift as we generally don’t display the cadence if it’s not coming from an actual cadence sensor.

I highly recommend using a separate sensor like from Garmin or Wahoo. That will give you a much more accurate number.

Is your resistance changing weirdly during ERG mode in a Workout? Or during regular riding? And does it do this WITHOUT cadence paired?

Hi Eric, I should have said I do use a Garmin sensor- to sure it wasnt that that was causing the problem I changed the battery etc. I was on it briefly today and the problem persists- its during a regular ride and I will check if it happens without cadence paired… 

You may also be having signal interference/drops. You can either submit a ticket with us or check your logs on a fansite like Zwiftalizer to see if this is the case.

Hi Charlie, my vortex is driving me nuts for the same issue…did you get to the bottom of it?



Charlie/Paolo, i appear ro have the same problem. I only havw the Tacx Vortex no extra sensors. When i do workouts i have to spin crazy fast to even get 150w of power, spinning at 120rpm. When i just use “The Ride” option i can hit much bigger numbers easily. Basically the workout mode is completely useless. Did either of you find anything out?

Hi Ted, I didn’t get to the bottom of it and sent my Vortex back. There seems to be an issue with Ant+ interfering with Bluetooth and vice versa, so choose whichever one your connecting through and disable the other. That might help. 

Good luck!