Heart rate way too low

Hello guys,

I started with tubo trainers and zwift recently and I noticed that during Zwift workout my HR is extremely low and also the perceived effort doesn’t match the power readings. I dont have power meter on my bike, but if I look on let’s say 6% grade climb outside, going full gas, estimated power in Strava is around 250-300W with heart rate around 160-170bpm. When doing the workout with target power of 250W, the perceived effort is much lower and I barely hit 130 bpm heart rate.

Today I ride sweetspot and FTP intervals (90-100% FTP) workout and my heart stays in recovery and endurance zone the whole time (average117, max 136 -I should be again around 160-165)

Or compare this Zwift workout ride (https://www.strava.com/activities/558355815) with this outside ride (https://www.strava.com/activities/555328113) I know outside there is wind and stuff, but the perceived efforts are realle too different.

When riding free in zwift the heart rate looks normal and subjectively it seems much harder. So there should be anything wrong with heart rate monitor. Could there be something wrong with workout mode?

I use Tacx Genius Smart, Garmin Cadence Sensor and Garmin Heart rate strap.

Thanks in advance for your advise!


Hi Dan, 

I’m sorry to hear you’re having trouble there. From what you’ve said it looks like you trainer doesn’t work properly in workout mode. I’ve just tested the same trainer in our office and it works fine so first things first. 

Can you please make sure you’re:

  1. Running the latest Tacx firmware (3.1.13/1.15.0) on your trainer
  2. Running latest version of Zwift (1.0.10998)

Can you also confirm:

  1. Model number of your trainer
  2. Whether you were paired as controllable trainer too
  3. Whether you were using ERG mode or not

This is what we need to check first, check it out, get back to us and we’ll take it from there. 

Thank you,


I am running the firmware 3.1.13/1.1.325 (it was provided to me by Tacx support, because during Zwift workouts, the zwift sets the resistance of trainer approx. 10 watts above the power level in demanded inworkout in ERG mode - i.e. workout wants me to ride 180W but trainer sets the resistance to 192W, after installation of this software this issue was solved).

i am also running the latest version of Zwift, I have the trainer paired as controllable and I am using the ERG.

Model number of my trainer is: Genius smart (T2080)

Thank you for our assistance!

Dan were you able to fix this?

Yes, I bought new trainer:-) it looks like the Genius Smart seriously overestimated the power output-like 50-80 watts in comparison to 4iiii power meter even when calibrateda ccording to the instruction. Only way to cure it was manually tighten the tension screw after calibration, which bring the reading to 10-20 watts difference, although the reading still vary during the activity, especially when tires gets more hot. So I bought tacx neo and all problems were gone.