Taxc Vortex seems to be off the power scale

Hi all,

for me it looks like my Vortex is absolutely over the power scale. Yesterday I did a FTP ramp test in ERG mode. I started with 100W and ended up at about 420W resulting in a 305W FTP which looks like far too much for me as I am not a really fit cyclist and didn’t do much during the winter. I looked a little bit strange right from the beginning: The test starts with 100W: I was not able to reach the 100 because the trainers ERG mode measured 120W all the time. I did not feel any resistance at all and it feeled like freewheeling. At 140W I started to feel some easy resistance. Going up to 260W it was quite easy pedalling. From 300W onwards it started to get a litte bit exhausting and at 400W I started to struggle.
For me it looks like the measured power values are about 100W too high. What am I doing wrong? I added some pressure to the backwheel and recalibrated the trainer in Zwift and with the Tacx utility.

My setup:
Tacx Vortex (Selected for power and as adjustable trainer) conncted via ANT+
Cadence/Speed Sensor (Selected for cadence) ANT+
HR Strap (obvioulsy) ANT+
Windows PC

1,95m tall
97kg

The FTP in older tests was also between 280W and 320W. So it looks like stable values, depending on my training. I started wondering about the values because friends of mine who are a lot fitte than me got FTP values between 210 and 250W with their direct drive trainers.

I would be very thankful for any suggestions fixing my setup

Kind regards
Michael

The Vortex was my first trainer, and it wasn’t particularly accurate. I never reached an FTP of 380 again, but maybe I was just younger. :blush:

Did you upgrade the firmware? I used mine again for a few days in autumn when I was waiting for a replacement part for my direct drive trainer, and after installing a firmware update things were much more realistic. Sprinting could still result in very short (less than a second) spikes, but up to the larger threshold area things were not too bad in terms of accuracy.

A few thoughts:

  • Do you use a training tyre?
  • You mentioned pressure, but not the amount. 8 bar is about right.
  • Calibration is a bit of hit and miss; getting exactly in the middle of the green area was never ideal for me; you should pay attention to wheel slipping as well.
  • You should do a 10 min warmup before calibration.
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Hi Eric,

thank you for the suggestions. Actually:

  • The Tacx Utility tells me the latest FW is installed
  • I use a Schwalbe training tyre because without the wheel was slipping a lot
  • The calibration is in the righter yellow/orange area. As you said in the green area it slips too much
  • I did a calibration before and after the FTP test but nothing changed.

For me it looks like the main issue is the 100W freewheeling. 100W should add a noticeable resistance or am I wrong?

100W is not a lot but for sure it should be perceivable. The Vortex is a fully functional smart trainer after all, it’s just not very accurate, has some lag, and so on.

Yellow/orange for calibration doesn’t sound good. What worked for me and my setup was still in the middle of the right hand side green area (and the green area is quite big).

Did you buy it new? I would contact both the merchant and Tacx about it.

Have you tried other training apps (e.g. Sufferfest, TrainerRoad, FulGaz, Rouvy)?

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