Wattage seems low?

Have just purchased a second hand Tacx flow to use for zwift. 

Having put my bike on the trainer, I noticed I had very low wattage numbers for the effort I was putting in. For example, getting to 100 watts took all my energy. I also attempted to do the calibration process on the trainer, and despite it starting with it asking me to reach 30kmph, I couldn’t manage to get past 20 at max effort. 

two possible problems are I have a 700x38c tyre and also that when I place the back wheel on the trainer, it doesn’t sit in exactly the centre; it sits slightly to the side but is still firmly against the roller. 

any ideas? 

  • Are you calibrating with the Tacx Training App, a Garmin or in Zwift?

    I have a 32mm tire and have a lot of trouble calibrating including (if using the Tacx App) continuous calibration instructions regarding the roller pressure against the tire being "too loose..." and tightening (via the blue wheel / knob thingy) to the point where I also can barely turn the pedals.

    Calibration with a Garmin (530 in my case) just calibrates without any adjustment to the roller pressure, I have a turn or so of the blue wheel but not tight.

    I have no experience of Zwift or Zwift calibration.

    Regarding your tire, ",,,Keep in mind that the maximum tire size for Tacx wheel on trainers is 700 x 32mm.,,,,"


    PS - centering of the tire can be done via adjustment of the right hand (viewed from behind, not the one with the lever ) wheel skewer holder which screws in / out