Tacx Flux Review – Followup on issues and response from Tacx HQ

My original review of the Tacx Flux did highlight a few issues with the system – namely a bricked trainer from myself and some discrepancies with the inbuilt power meter. Since then I have been furnished with a replacement trainer, new firmware, and a long phone call from Tacx HQ – read on for the Tacx Flux REDUX, Inc phone transcript!

Tacx Flux Issues – Tacx HQ Interview Response

If you are interested specifically in the conversation with Tacx HQ – skip to the bottom of the page

So we’ve see a few varied stories about the new Tacx Flux. I am currently on my second, after having one unit make some odd noises and producing some slightly screwy power data, Shane Miller has managed to munch through two units!

As a result of my experiences, Tacx shipped me a new unit with the latest firmware, which I have again been testing


So far, this unit has a couple of hundred KM’s on it, and while I may not have Shane Miller’s Kilowatt legs, I’ve managed to reliably push the unit to 800-900 watts several times, without the unit throwing out smoke/dust/worrying noises.

Tacx Flux

However, (there is always a however in these stories isn’t there!), on my power meter graphs using the PowerTap C1 and the 4iiii Precision, this do not appear to be 100% in line when looking at the powermeter contained within the Tacx Flux. Oh the wattage recording by the Flux is much better than during my initial review, and crucially the responsiveness has been drastically improved, which will help racers on Zwift, BUT I am still looking at a not insignificant wattage reduction to the smoothing effect, and this cannot simply be ignored

Things look okay on the larger time frame graphs.

Tacx Flux

However, if we zoom in, to a 5minute section of Zwift’s “Jon’s Mix” we can see where Tacx still has firmware work to do

Tacx Flux

Tacx HQ Conversation

But there have been enough comments and discussions behind the scenes on TitaniumGeek that I ended up with a phone call from Tacx HQ, who tried to provide some particularly related is questions from readers. So, below is a collection of Tacx responses to the questions I posed them


Some companies allow the public access to beta firmware. Things are improved in your current firmware, but is there any chance of the public being allowed access to the beta firmware you are testing currently?

There is a team of 30 riders testing out the latest Flux firmware, to make sure that it improves still on the last release. Installing a beta firmware on the Flux might not actually improve things for the end user, as each internal release may be focused on addressing one part of the Flux experience, and thus there is the potential for a user to end up with a poorer overall experience when running a test firmware. We only release publically firmware we are proud of, and which improves things for the user. We appreciate that there is work to do, but we’d prefer to do that steadily and well, rather than rush and release a beta firmware that both we and the end user isn’t happy with

TacX Flux

Some riders have reported black dust building up on from vents on their unit, 

We are aware of those reports and were investigating internally, anyone with issues like that should contact their Tacx Flux vendor.

What about current owners who are concerned about the reliability of their unit?

All Tacx Flux units have a 2-year warranty, and we will guarantee to look after all of our customers.

(I found that response a little lacking, and pushed for some more information.)

There’s a small number of units (1,7%), which represent a very small fraction of the total first production run, may have issues with the shaft on the turbo, due to an assembly factor in the factory. When a large load is put through the Flux on those units, the Flux chassis has flexed, allowing the V-belt to jump/become misaligned. We are aware of the issue have addressed this in the factory

But what about current owners? That doesn’t address their concerns of potentially having an affected unit

We expect very few owners to be affected by this issue. We want to have the best product on the market. Part of that is recognising that some units fell below our quality standards. We will look after any Tacx Flux owner who has problems, that’s a vital point. Realistically put, anyone who is riding their Flux for about 60mins, and sees no issue is unlikely to have an affected unit – as seen with yourself and Shane, units with this assembly problem become apparent with very little time in use


Shane, I and a few others have seen a wide range of serial numbers affected, would Tacx consider a recall, to address this issue?

The problem stems from an assembly issue in the factory mainly. We don’t have a list of affected units but do not expect future units to be affected. Again, if a user has a problem unit, it will rapidly become apparent, and we ensure that we will look after that individual

So we know that there has been an issue with the belts inside the some Flux units, has that now been identified and fixed?

We’ve seen two issues affecting the transmission belt:

First issue

The first issue was caused by the tensioning wheel that might be assembled too closely to the steel chassis. During a workout and especially during sprints this wheel is pushed against the steel chassis, causing internal damage and the transmission belt running off. This problem will occur within the first hours of use if it doesn’t; your FLUX is ok.

Please note this problem didn’t occur during our durability and stress tests, which was the issue with Shane’s FLUX during his sprint. After the issue was noted and resolved, we made the necessary adjustments to prevent this from happening on all future FLUX products.

The number of products that got into the market and might have this issue is small, the current return rate is 1.3% for this specific issue.

Second issue 

Analysing the second issue was a bigger challenge as it was more difficult to reproduce this incident in order to find out what caused the belt to run off the pulley wheel. This second issue also occurred with a FLUX sent to Shane Miller. When sending this second FLUX, we double checked every assembly step to make sure this unit was perfect. Yet, this thoroughness has led to too much tension on the EDCO freewheel hub damaging the connector between the large metal pulley wheel and EDCO body. This weak spot cracked and caused a chain reaction displacing the large metal pulley wheel and letting the tensioning belt run off. This resulted in the grinding noise and smell noted in Shane’s video.

In order to prevent this issue from happening, we have tested the maximum torque on all the parts and adjusted this accordingly in the production process.h

At the moment we only have a few cases with the same issue as Shane’s second FLUX. The vast majority of issues within this category is coming from the first issue.

There have been suggestions of a design issue inside the Flux, rather than merely an assembly problem when people have taken their units apart, can you comment?

Part of the problem affecting the small number users relates to factory assembly, contributing to the movement of the V-belt as mentioned. We have addressed this now.

We can offer a tour of the factory to TitaniumGeek, to see how the Flux is assembled, and allow demonstration of the previous issue, along with the resolution, which would hopefully address user confidence.


So there you have it – the answers as Tacx see’s them, and hopefully a dollop of reassurance. I am happy that the Flux here hasn’t sprouted any more issues, BUT I’m still waiting for improvements to the firmware, but I’m not hoping to be able to talk to that team in person later this month!



So the Flux had a bug in the factory, and they state that the bug has been squashed.

It seems, at least from this conversation, that Tacx has taken this issue to heart, and crucially I got the very clear impression that they will not allow an affected Flux customer to be affected for long (although you’ll note that I couldn’t manage to get any qualification on how long, long is!). Hopefully, we’ll have a physical demonstration of what the issue was, and video blog from the factory, to literally put us more clearly in the picture, and reinforce the message which has come from Tacx

Any questions or comments, stick them below!

UPDATE – my tour around the Tacx factory in Holland is now up, where I talk to the chief engineer and have him explain to TitaniumGeek readers what happened to the Flux, and how they have addressed it

Click here for “The House that Tacx Built”

Tacx Factory

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  • Hesham Sherif

    I have an option to get a Flux with the same price of a kick snap, but i guess i will go for the Snap because of the customer service, i have had long discussions with them and they are completely dumb!

  • Hesham Sherif

    Never buy a Tacx again, my Bushido is fucked up and am throwing it away, their customer service is just horrible

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  • Cliff LaCoursiere

    There are a lot of issues with the Neo as well so upgrade with caution, or at least with the expectation that there’s a high probability that it too will fail.

  • Cliff LaCoursiere

    You’re fortunate to be dealing directly with the factory. I’ve purchased a Neo that bricked at ~80 hours as recorded by Zwift from a UK dealer that shipped to the US. Tacx insists that it has to be returned to the selling dealer – A $500US proposition.

  • Wow sounds like appalling customer service from tacx. Can’t even find any info addressing this on their offical or FB page. Considered buying the flux (or even the neo). But nope… they ought to recall all the units for replacement (like motor manufacturers do), but instead the consumer is left alone.

    Personally I used to have an Elite Turbo Muin. No service from Elite either so same-same.

  • Greg
  • Teak

    I think that the assertion that the Flux will fail within an hour if it is going to do so is nonsense. Mine failed at 234kms – same issue of slipping belt and horrible burning smell. My vendor immediately requested the unit back and offered an exchange, though I am not confident that this will not be a re-occurring issue given what I have subsequently read on Amazon and other review sites, so will push for an upgrade to a Neo and pay the difference.

  • Jorge L Rivera

    Take a look at Amazon customer reviews. They all complaint about the same belt issue.

  • Greg

    Hi I’ve just purchased a tacx flux and it was making a noise from the start I took the cover off and could see the idler tensioner wheel was rubbing on the back plate. I decided to use it without the cover on after an hours use during a sprint 6-700 watts the belt came off the pulley. I put it back this happened again twice. I’ve posted videos on you tube. Then one of the magnets came adrift and the flywheel wouldn’t turn. I would not buy another or recommended it to anyone. Buy a kick R of Cyclops

  • jpow

    what is your serial number?

  • I think there is a lot of info to suggest avoiding the lower serial numbers with regard to the Flux

  • Andrew

    I am considering changing from my Vortex Smart and getting the Flux but after hearing about the issues I’m not sure if I shoud just get the Bushido as an upgrade now instead?

  • There is nothing else at the same price bracket. – I’d suggest KICKR SNAP if looking under <£700, if you can afford a little more the Cycleops Hammer or the full sized KICKR

  • Jack

    Ive decided to bite the bullet and get the kickr2

  • Andrew Palin

    For what it’s worth, my Flux faulted after 130 kms of riding. The unit started slipping on each pedal stroke and is now back with the supplier. I’m not reassured by the number of returns I’m hearing about and I’m hoping for a refund so that I can buy something less flaky. Any recommendations?

  • Cheers Stephen. It does sound like a firmware update will get this sorted (fingers crossed)

  • Steven DV

    James, FYI I posted a PPT containing my own power accuracy review in the Tacx Flux owner Facebook group. For me, it too showed not enough power compared to my Rotor INPower. The one exception beign the steepest part of the Zwif col: @ 50% simulation, there the pwoer numbers where more or less inline with Rotor. On all the rest, I was lacking between 15W and 70W.


    Steven DV

  • Drafting is largely down to actually Zwift rather than the trainer. There will be some impact on drafting depending on the responsiveness of the trainer, but currently it is not something I have noticed issues with testing any of them – I know for example that Wahoo worked on their firmware a while ago, which I think improved Zwift responsiveness

  • Pataki Ferenc


    Thanks for your reviews! In your reviews you always discuss behavior in Zwift, responsiveness and sprinting. Could also specifically comment on drafting? I have a Tacx Vortex, and I am having difficulties with drafting. I assume it is due to the long reaction times of the Vortex. I am considering upgrading, but unfortunately I have no access to any other trainer, and I am not sure how much better another trainer would be in this respect. First I considered the Flux, then after reading the reports on it I am leaning towards the Drivo. Absolute accuracy is not a concern for me, what I am after is the realistic feeling of acceleration, drafting, sprinting, terrain changes. So the question again: is there a significant difference accross the trainers in how easy it is drafting with them?

  • Jack

    Ive returned mine after no support or response from Tacx. 2yr warranty is useless when you cant even exercise it

  • Rich W

    Interesting reading. I’m on my second flux and have experienced the same grinding noise with both trainers, which seems to be as a result of the first issue. Taxc have advised that they are aware of the issue and I have been awaiting another replacement unit for a month now. I think their estimate of 1.7% of affected units will likely increase. I am considering an upgrade to a neo!

  • John Walker

    Thanks James, I noticed on the warranty documentation that came with the Flux the one year is the period from purchase. I would be grateful if anyone could relay where the two year period noted.