Workout mode watts too high

I have a Tacx Genius Smart (latest firmware), calibrated correctly, which works fine until it comes to the Zwift Workouts.  With ERG enabled the watts the unit is making me keep to is 8 - 10% higher than the level Zwift wants me to do for the interval.

This was fine at the start of my 12 week FTP builder as the watts required were quite low, but last night I did week 2 day 4 where I was supposed to maintain 230w for 5 minutes (My FTP is 265).  I don’t change gear, I keep my cadence to 85 - 90 constant and keep progressions between intervals smooth.  ERG mode was making me keep to 245 - 255 watts.  As those of you who understand ERG mode, changing gear or cadence doesn’t help so by 40 minutes in I was completely spent (I have a cold so couldn’t maintain such a high % of my FTP)…  Eventually I had to turn the ERG mode off and manually with gears and cadence keep the watts to the target which was fine.

Is this an issue with the turbo, or Zwift?  I would assume Zwift, as surely it sees the higher watts and through ERG mode reduces the brake resistance to suit.  I know many of you will say “Turn off ERG mode”, but if that’s the case I may as well have bought a cheap non smart trainer.

I have seen similar forums discussing this issue with the BKool Pro but found no resolution to this.

Help would be really appreciated as with ERG mode on I stand no chance maintaining the watts in the latter weeks of training when they sit around my FTP.

I would add that the cadence zwift reports is also higher by about the same % than my Garmin reports.

I have found the same thing with the Tacx Genius. Zwift tends to add about 15W to what is being asked. Not sure if other folks have this issue with different turbos. Generally knock 10W off the FTP before riding or as you said you end up riding nearly 20W more than your FTP.

My Tacx Neo adds a little, and it seems to be worse at lower wattages. For some specific examples from workouts this week:

  • 10 minute recovery with a 95w target, Zwift and the Neo held me at an average power of 101w.
  •   A pair of 25 minute intervals with a target of 134w, average power for both was 137w.
  • 15 minute Intervals a with a target power of 185w, average for the intervals was 186.

For whatever it’s worth, I’m looking at wattage from the Neo on Zwift and from my power meter on my Garmin simultaneously. The two match as perfectly as could be asked. Well within the 2% claimed by each, rarely more than 10w apart, and never that far apart for long. Usually within 3-5 watts of each other. So this is a “command” issue, not a “feedback” issue.

With the Tacx Genius it seems that ERG mode adds 8% consistently across the range. This makes doing hard workouts with a true FTP score practically impossible.

I have the same issue with Tacx i-Genius (ironman). In ERG mode the watts are constantly appr. 10% above target, which for sweet spot intervals effectively makes them threshold.

This happens in both Zwift and Trainerroad.

Found this thread which suggests it’s a unit defect:

For TrainerRoad, I am going to try using the “PoweMatch” feature they have, which somehow adjust the ERG resistance based on actual power output. Will comment here whether it helps.


Yesterday I got a new version of the Tacx Genius firmware from Tacx; version 1.1.325. Not sure why this hasn’t been release yet but this completely resolved the issue. The Watts in workout mode are now pretty much spot on.

If you are have issues just ping Tacx on FB and tell them ERG mode is not working and they should send you a bin file you can use to update the firmware.

Well thank you so much Carl. I’ve reached out to Tacx support and after the update to 1.1.325 the ERG mode issue’s solved for me too.

Another vote here for that, I had the same issue, but the new firmware resolved. Now I only have the issue of the Genius reporting power 10-20% higher than Vector 2.

Same here. My Tacx Genius reports 140 watts White my P1 saus 80!!!

not sure What to do here. This is during a workout with the Tacx in ERG mode.