Power low for effort

I just bought the Tacx Vortex and been using it with Zwift for past couple of weeks. I use a Garmin 510 but do not use a power meter. Have to rely on the virtual power meter.

It seems to me that my power output is very low for the effort I am putting in - particularly on the flats and downhill. Hills are a bit better. But it’s making taking part in the group rides very difficult indeed.

Any suggestions? Is there a way to calibrate virtual power or Tacx?


Hi Sean,

If it’s the Tacx Vortex Smart, then it should be a Smart Trainer already. You can calibrate it via the Tacx App on your mobile device and then pair it as a ‘Controllable Trainer’ when using Zwift.

If it is NOT a Tacx Vortex Smart (instead an older version) then I’m not sure what trainer you are trying to pair it as but we do not have an accurate power curve written for it so your data will be off. In this case it looks to be a bit too low.

Thanks Eric. It is a Vortex Smart trainer. I have paired it as a controllable trainer. But it still seems off to me.

Have you calibrated the trainer with the Tacx app? Essentially ensuring the brake unit is pushed hard enough against the brake to give resistance, but not to hard to lock up?

If you have, then there are two possibilities. Either the Vortex delivers to much resistance due to an production error (there were a few Tacx brake that had this problem). Or you are not as fit as you thought :). Best would be to either borrow a (bike with a) power meter somewhere, and check if the power Tacx reports agrees with the power meter measurements. Or try another Vortex, and see if it gives the same problem, or invite a friend, and see if he also has trouble reaching his “normal” wattage on your Vortex…

If your Vortex is delivering a to high resistance for the Wattage reported, you should return it to the dealer/manufacturer.

Thanks. Will double check calibration again and make sure Bluetooth off. If it is fitness related then I don’t know how I am getting around my weekend rides. Either that or there is some serious weight/power doping going on in Zwift.