Power during workout

(Bertram Redmeijer (B)) #1

Recently I made a workout, with as goal a steady z3 exercise. I set the required power to 90% of my FTP (265 Watt), as 90% is often cited as the threshold for a z3 training. And that seems correct when you look at the numbers: the threshold between z3 and z4 is 275 Watt for me (according to Strava).

When running the excercise it did give me a target of 265 Watt, but in erg mode the resistance was concistantly 288 Watt. This seems to be so for all target levels, actual Watts in erg mode are 7% higher than asked for by the excercise.

So my 90% FTP training became a 96% FTP training, and something complete different from my intention.

I ride a Tacx Genius Smart.

First question: is this a Tacx issue, where the intent is to set the watts required to 265, but due to communication failures it goes to 288? Or is it a Zwift issue, where a required 265 is set to 288 just to make sure you dont drop to low?

Second: is there a way to correct this? (Other then fudging the FTP or the % required - it would be odd to have these values, and then use others to set up the excercise).


(Carl Nolan) #2

I have raised a support ticket for exactly this issue, also using a Tacx Genius Smart. if anything comes of it I will let you know. My power is also 7% too high.  

Also, I have used the Tacx TTS software and when you select X Watts you get roughly that, so it looks more like a Zwift Issue.

(Dan Urban) #3

I had same issues with Genius Smart, today I updating Genius’s firmware and also there were an update in Zwift and during workout, I have lots of trouble reach the desired wattage level -even with constant cadence my watts falling around 10-15 watts below the target especially on lower zones. Plus I was unable to sustain good level, the power jumping a lot. Not sure if it was caused by Zwift or firmaware update.

(Carl Nolan) #4

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.