Calibration difficulties using Tacx Flux

I am finding it impossible to calibrate my Tacx Flux Smart with TR. I start pedalling and right before I hit the pace I need to complete the calibration it goes super high on reststance and I am never able to do it. I have calibrated with Tacx app but is that ok for when I use TR?

That sounds odd, I usually have no issues calibrating mine with the TR app.

Have you checked that you are on the latest firmware? Apart from that get in touch with

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Yup, totally fine. Calibration with any device/app sends the calibration data and stores it in the trainer. So it will be used for any app, even if its a different one.

I would suggest contacting so they can see if there is something that needs fixing on their end.

Never had a problem either, takes a few seconds to get to speed then all is good :man_shrugging:

I have actually had similar issues, its only happened a few times and I want to say recently. I get to about 18-19 and something changes and the power needed to hit 20 is very high. I just wrote it off but interesting to hear someone else having same issue. I am on the latest firmware.

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Apparently this does happen on the Tacx Flux S a guy at TR talked me through it as it’s the trainer he uses and he has the same issue. He said to go in the hardest gear you can and thrash it out from there. I did it once like that but had to stand to get it done, I had to try so many times i had done what felt like a mega workout before I succeeded!

TR programme and calendar is much better than the other apps, Tacx included, so I will continue to use that for training I will just sack off calibration side of things with TR. I can calibrate it easily with Tacx app and Chad said that is fine.



Yeah, you can calibrate in the tacx app without creating an issue with the reading. It’s also better to calibrate after around 8 mins when the trainer is warmed up.

Strictly speaking tacx doesn’t specify you should calibrate after every ride, but it’s been shown to increase accuracy if you do so.


I have exactly the same issue. In fact, I have two!

First is the same as mentioned above. I start pedalling and at around 18 mph the resistance jumps significantly and I would guess I’m having to push 400+ watts to get the speed above 20mph for the calibration process to start.

The second is that I usually have to do this at least 5 times before it gives me a correct reading. This is my fourth Flux (i know). The first 3 were the original Flux and I’m now on a Flux S and the problem is the same. When it works the reading is usually 6.3335 seconds (there or thereabouts) but when it doesn’t it comes out at 0.1 or 0.2. It’s very frustrating that I have to do around 4 or 5 very hard efforts before I can even think about starting. My Flux is in my garage which, right now, probably gets as low as 0 degress c overnight, so I figure re-calibration is warranted given the temperature changes.

And this is why I don’t use the Tacx app. I am sure the issue re. calibration is with TrainerRoad, rather than with the Flux, but I don’t know. The Tacx app doesn’t actually show a calibration reading, it just says it’s calibrated. I don’t want to take the risk that it is the Flux that’s the problem and I’m calibrating spindown at 0.1s without even knowing it.

It is very frustrating.

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Those are links to a couple of things I did, the first ramp test I thought I was in ERG but not sure I was. The second is the 8 minute FTP test. I can’t

The other test was the Tacx Threshold test:

I am loving my Flux, Flossie, and I love the TR app and workouts so I will just sack off calibration on the TR app and keep going with calibration on the Tacx App.

I love TrainerRoad too. I’ve been using it for years and wouldn’t go anywhere else.

I am not 100% convinced about the Flux. The resistance floor is VERY low, so low that sometimes I can’t hit the wattage in my easiest gear. It’s also mighty unreliable (as I said, I’m on my fourth). And it’s not massively accurate in its power readings at certain speeds (for example, at around 120 watts, my power meter reads 120 whilst the flux is saying 100/95. It gets a lot closer at around 250 watts, and where I’m in the big chainring and mid-sprocket (usually within a couple of watts). I suppose that’s where it really matters, it just means I don’t trust the reading I’m getting.

And whilst i would just use the Tacx app, this still poses two issues for me:

  1. I want to do everything in one place. I don’t want to have to jump between apps, disconnecting the trainer from each one each time, just to calibrate it; and

  2. I have a power meter and use the power match functionality. I have noticed that this doesn’t work at all when the calibration of the trainer is wrong. It just doesn’t change the resistance.

Don’t get me wrong, I am over the moon with TR, and the Flux, when used with a power meter, is just fine as a tool. That said, when this one breaks (which I’m sure it will), I’ll be sending it back and getting a Neo or Direto.

I spent a lot of cash on getting it so this is not what I wanted to hear., but thanks for the info. I will have to plug on with it :flushed::sunglasses:

I feel like this is a more recent issue, maybe since an application update. I have had the Flux for about a year and never had an issue until recently. Nothing has changed on the Flux, including firmware. My assumption is that something in TR is changing before we hit the 20 MPH mark when its suppose to start the calibration process. This is something that the programmers will have to figure out and likely will over time. I’m not to worried about it, I have calibrated it and its working as intended. I only calibrate when something changes, bike, excessive temp swing, etc.

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Cool :sunglasses: