Tacx Flux2 "dumbing down" on 45min+ rides?

Hi there,

First post here.
I have been enjoying Zwift for several weeks now and have the time of my life :slight_smile:.

I am using a Tacx Flux 2 smart trainer and have experienced a few dropouts.

There is however another issue which bugs me : on long rides it happens frequently that the trainer seems to "dumb down " for lack of a better expression (my apologies English is not my first language): suddenly the trainer stops reacting to gradient changes through changes in the resistance I can feel in my legs, but, for a given gear, keeps roughly the same resistance but varies speed.

To make things clearer, let say I am on a 0% incline on a given gear, and I hit the start of a climb, if I stay in the same gear I will feel a change in resistance and if I want to maintain speed I will normally have to put out more watts, and possibly get out of the saddle.

This works for 45 to 55 minutes but then, for no apparent reason, if I am again on 0% incline on a given gear, and I hit the start of a climb, I will feel no change in resistance, will continue to put out roughly the same wattage, and will only see my speed drop. If I want to put out more watts I will have to select a larger gear.

Am I the only one experiencing this issue? I have browsed the net for quite some time now and have not found anything referring to this…

Cheers from France,


I have Flux2 as well. Had longer rides without an issues, and shorter - with.

Not sure if the Flux2 is to blame… can you put a time on the issue? Has it started recently, or have you been experiencing such for some time now?

Btw, there was a (unrelated?) F/W issue with the Flux2 - you might want to verify your trainer’s F/W version.


Merci :slight_smile:!
I have experienced this issue almost right from the start.
And my apologies, but what does F/W (in our context of course)?



Firmware :slight_smile:

Makes sense, thanks :wink: !

if you pair the trainer for power and cadence does everything else still work? do you still pedal and show power readings?

do you connect via ant+ or bluetooth to zwift? and Windows, IOS or android versions?

is there a chance that something else is controlling your trainer? an app on your phone or a garmin device can also control trainers.

next time it happens try unpairing the trainer and then repairing it to see if this helps.


By any chance, are you riding a structured workout in ERG mode? Because this is how ERG mode feels.

In free ride mode, (aka SIMulation mode), a smart trainer like the Flux 2 will respond to gradient changes by changing resistance.

I use BLE and a MacBook, no other device, and I have tried unpairing the traîner. In this case everything starts working fine again, but I would love not having to stop and unpair…

No, I am not using ERG mode, but you are right, this phenomenon coule be almost be described as the trainer switching to ERG mode mid-ride…

I would suggest using an ANT+ dongle - it can be a bit more reliable. if you look on amazon you can get them relatively cheaply.


You might try resetting the Bluetooth module on your Macbook.