ERG Mode and Tacx Flux S, Power2Max, controlling with lower wattage


I am using the following equipment:

  • TACX Flux S,
  • Power2Max Powermeter
  • Win 10-Laptop with an Ant±Dongle and an USB extension-cable (Dongle is placed right next to the trainer).
  • Most of the workouts I am doing with the smaller ring in front (34) and about 23-25-27-30 at the back.

I have the following issue:

During a SST-Training the software seems to have a problem, when the wattage is dropping from, for example, 190 watt (sst-intervall) to a cool-down-part with about 85 watt. The wattage drops, but it only drops to about 110/120 watt. Now, when I am switching from ERG-Mode to RESISTANCE-Mode and back to ERG-Mode manually, everything is fine. Now the software addresses the 85 watt and the trainer can “hold” them.

From my point of view it is not related to the “wattage-floor” of the trainer, because if I am switching between the modes manually, everything is fine. All the time my cadence is between 85 and 95.

Today I did another test (same gear-set: front 34, rear 27):

  • Warm up for 5 minutes with 85 watt (85 cadence): Everything is fine, the software addresses the wattage and the trainer can hold the 85 watt.

  • 10 Minutes intervall with 195 watt (85 cadence): Everything is fine

  • 5 Minutes cool-down with 85 watt (85 cadence): Now it happens, the wattage drops only to about 120 watt. Now shifted from 27 to 30 (rear), the wattage decreased a little bit to about 105 watt. But the wattage did not decrease to the 85 watt. --> Now I switched to RESTIANCE-Mode and back to ERG-Mode manually. The everything was fine, the software addressed 85 watt and the trainer did id as well.

Right after this, I did similar tests with Zwift. And I did not have any issues like this with Zwift.

For me it looks like, that trainerroad (in combination with the TACX FLUX S) has an ERG-Issue.

Do you have any ideas, what I can do (it is a pain to switch permanently the mode during a SST-Training g).

Best regards


1 Like

I feel your pain. I bought the Tacx Flux on offer not so long ago. One if my gripes was the high wattage floor.

I guess the S is a newer version so it’s strange the wattage floor changes between intervals. Mine was around 120-130 in the middle of the block. Always had to change down.


Well, I think it is not related to the wattage-floor, because at the beginning of a workout the 85 watts are hold perfectly. And during a workout, if I switch between the modes manually, the 85 watt are held perfectly as well.

It is only an issue, if I do not switch manually.

Maybe it is related to the wattage-floor in combination with the temperature of the device (because mostly the issue occurs after a time-period and never at the beginning of a workout).

BUT on the other hand, the question is, why does this not happen with Zwift?

Best regards


have you solved the issue?