Tacx Vortex Smart + Zwift: inconsistent power readings

Hi everyone,

I have a Tacx Vortex Smart trainer and a Wahoo Tickr heart rate monitor connected to my Macbook Pro (OS Catalina). I’ve been doing workouts on Zwift since around 2 months ago. I did an FTP test back then and got an FTP of 255w. I trained three times a week and a month later, I did another FTP test: my ftp increased to 295w. That’s when I realized there’s something wrong with the power readings. Today, when pushing 250w for 10min, my heart rate was very high and I was exhausted. A week ago I pushed 290w and I could still talk to my girlfriend while doing so. Also, since today, the cadence readings are off too. I knew I was doing around 90rpm, but Zwift showed around 120rpm, and it also jumped a lot…

I’m using a trainer tyre with a pressure of around 100psi / 7bar. I’m using the Tacx Utility app on my iPhone to calibrate. When I put tyre resistance is in the exact middle, I feel it is slipping a lot. So I tighten it a bit, so the calibration is more to the right, but still in between the two white lines.

It is a frustrating experience as I don’t know what is correct and what not. The only thing I’m pretty sure about is my heart rate. But now I don’t how to organize my workouts anymore, as I don’t know my FTP because of the weird readings.

Anyone having similar issues? Or does anyone have an idea what might be the issue here?

Many thanks!

Hi, We have a tacx vortex smart too. I wouldn’t use the tacx utility app to calibrate because it slips whenever we use the app to figure out what is just right. I do feel that the power is a bit inaccurate at times. We have a direct drive trainer which is what I normally use but when I go back to the vortex I feel like I lose a lot of watts.

It called inconsistency. The worst thing in power measurement. It is the biggest problem with almost all wheel-on trainers. I already experienced it in 2013, struggled with it (i had bike powermeter too, so it was even painful) and bough a Neo in 2015 immediately. If You wanna get accurate power numbere, buy a direct drive trainer (Neo, H3, Elite Direto, Suito and Kickr series, it is an accuracy order also, from the most accurate to less accurate or less reliable. I have problems with Kickr’s overreporting by default, but lots of riders love it because they get extra 10-20watts/3-5% boost indoor)

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The neo is a great trainer. If you are looking to get a direct drive I would go for the neo.

Thanks guys!

I’ve decided to sell my Tacx Vortex second hand and purchase a direct drive trainer.
Unfortunately almost all direct drive trainers are sold out, everywhere!
The only one I could find was the Kicrk Core on the Wahoo website.
So I’ve just ordered that one. I’m sure it will already be an improvement to the Vortex.