Trainer resistance "bouncing"

Hi there!

I’ve been having some great rides on my brand new Tacx Flux 2 hometrainer!
I just got halfway to level 8, but seem to begin to have some trouble with the trainer…

The resistance seems to “bounce” and is very inconsistent. Of course this is something I feel mostly on Alpe Du Zwift. It feels like the trainer let’s go of the resistance, getting my wattage all the way up to 300+ for just half a second, then the resistance comes back an I instantly drop to 250 watts.

It’s extremely inconsistent, and I can’t seem to be able to get it to stop doing this…

I’m using the companion app on my iPhone, trainer is calibrated directly in the Tacx app before riding, and of course, via the companion app, connected to my Apple TV - on the latest firmware, the hometrainer on that as well.

Please help!

Thank you in advance!

Hi @Marcus_Michaelsen_DB, welcome to the forums.

You may want to check out this thread:

Hey @Dean !
Thank you so much! I’ll look in to this tomorrow when trying to do it again…

I did have windows open, and it was very windy, so I got a lot of air through - I did complete Alpe Du Zwift once, without any issues at all - this time, the way I got up, I was 25 seconds ahead of my PR, so of course it’s sad to have to abandon the time, but damn, couldn’t ride with it…

Don’t think it should be overheating, but I’ll look in to it the next time I ride - thank you!

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Agree - it looks like that trainer is rated for 800 watts max so I am surprised the problem has been around as long as it has. But throw a fan directly on it and x your fingers.

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Definitely will do! Thank you!

That thread is about the wheel-on Tacx Flow, not the direct drive Tacx Flux here. I doubt it’s overheating.


Oh bugga, mis-read - thanks Steve.

The gradient on many ADZ’s hairpins drops quite significantly for a few metres. Any chance this is where your brief power drops are?

Unfortunately not - mid section it just drops, and then comes back half a second later. When it happens I always look at the gradient, but I just see it at a stable 8%…

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Dear Marcus

Did you happened to find any fix for this issue? As it seems i have the same issue. I normally use Zwift in ERG mode so I don’t feel this power bouncing. But today i want to check my Alpe du Zwift record and in the first leg i started feeling this power bouncing it is very bad as you can feel it in every paddle stroke.

Anyone found a fix? I have the same issue during Tour de Zwift races - normally I do sessions with EGR mode and then there is no issue.

Anyone know of a fix. I have the exact same issue. Happened every time I did alpe de Zwift on nearly every section. Resistance dropping for 5-10 seconds whilst mid section even though the gradient figure remains the same. Very disruptive and off putting.