Tacx Flux Smart Turbo Trainer Review – Zwift Gear Test – TitaniumGeek

Following in the glut of direct mount turbo trainers releases this year, Tacx has launched to Tacx Flux. With very similar internals to that of the TacX Neo but without headline-grabbing features such as road feel and downhill simulation. Instead, we save a considerable chunk of money and gain a smaller package. So have Tacx made the Neo a baby brother, to sit supportively in the lineup, or have they created a cut-price cannibal to gobble up the larger models sales? – let’s see in this Zwift Gear Test!

Tacx Flux Smart Turbo Trainer Review – Zwift Gear Test – TitaniumGeek

TacX Flux

So, Tacx is one of the oldest turbo trainer manufacturers, starting off in 1972 by producing simple rollers. Thus given how long Tacx have been in the market, it is not unsurprising that the company also produces probably THE most technically advanced trainer on the market, in the Tacx Neo, which although technically brilliant, was troubled by early birthing pains.

The new Tacx Flux promises to be the epitome of trickle down economics, with the advances seen in the Neo, being trimmed down and repacked into a smaller, cheaper unit. But rather than just an exercise in tweaking and repackaging technology, Tacx has actually created a new category/price point with the Tacx Flux.

Currently, manufacturers tend to split their turbo trainers – direct mount as the halo device around the £1000 mark, then down on to wheel on turbos at around the £500 price point. With the Tacx Flux though we have a direct mount trainer, with fewer bells and whistles, but at an unheard of £700 price point. Think of the Tacx Flux as the BMW 3 series to the Tacx Neo’s BMW 5 series. Still a premium product, but hopefully with a wider customer base at a lower price!

Initial Impressions

My first encounter with the Tacx Flux was actually a little backwards, I’m used to getting a device first to poke at for a few days, learn it’s ins and outs, and then set tot using it for a while to get a true idea of how the unit feels. But here I ended up using the Tacx Flux initially during the recent ZwiftCon event, where I brought along one or two other trainers for fellow Zwifters to test out!

 TacX Flux

But initial reports from myself and Zwifters related to how astonishingly quiet the unit was, quite stable, and overall very responsive with the resistance changes on Zwift

With that brief opinion in place, let’s return to the usual approach of a Zwift Gear Test and have a look at the design of the Tacx Flux and what is in the box.

Tacx Flux Design

TacX Flux

Opening the box, we’ve got the ancillary gubbins to allow you to put the trainer together. Power cord, two lock rings for 11 or 12 toothed cassettes, steel training skewer and bolts. Included spacers allow for 9, 10, or 11-speed setup, whilst the inclusion of an Allen key for attaching the legs to the Flux is a nice addition

Of note, there is no separate power adapter, which personally I like, just a standard kettle lead. The fewer power adapters I have to lose or stand on, the better!

TacX Flux

The legs on the Tacx Flux are a very separate, and very discrete component in the box – they also weigh a tonne!

TacX Flux

The first thing that struck me about the Tacx Flux is the appearance/design. The legs on the Tacx Flux once installed are VERY fixed. Currently, all other turbo trainers on the market have at least a nod towards being able to collapse/shrink the turbo down in order to store it away after a training session if needed. In order to reach the current price point, whilst producing a sturdy trainer, Tacx has opted for a completely fixed design with no facility to fold the Flux up – the legs are pushed directly into the structure of the unit in a metal and plastic sandwich. The lack of the handle on the unit, anywhere, reinforces the view that Tacx intends you to set up the Flux and leave it standing.

TacX Flux

The legs are rather heavy and definitely an integral, structural piece of the unit, which are bolted through the metal ends of the legs and straight through the unit. The Neo as a little bit of flex built in the unit via the materials used, by comparison, the Tacx Flux is rigid metal on the inside and gives a really locked down feel on the hills of Zwift

TacX Flux

To clarify, you could take the unit apart after doing a Zwift session, but it wouldn’t be a 30-second process, these are proper 8mm bolts, not a quick twist to release lock

TacX Flux

TacX Flux

Plus pulling the legs out of the unit when unbolted is NOT easy, as I found taking the unit apart to send it back after this review – you really want to put your foot on the trainer to help you pull (although not a great idea!)

TacX Flux

Once the unit is together, it’s time to apply the cassette. Tacx does not provide one in the box, but I can see the logic, especially as a great many people like to mimic their road setup, so use the same cassette as their outside gears to help with training.

Like the Tacx Neo, the Tacx Flux uses an Edco MultiSys freehub, meaning that the Flux can use either a Shimano or a Campagnolo cassette without needing a change of hub. This also would impact on Tacx decision not to provide a cassette in the box, and I think is a fair trade

Tacx Flux

The freehub is a little fiddly to get the cassette to slip on due to the extra/different grooves compared to a normal campag/Shimano, but as long as you look for the markings indicating which cassette goes where there shouldn’t be too many issues!

Tacx Flux

After sliding the cassette on, you need to ensure you apply the correct lockring, as a result of the Edco freehub you can’t use the standard lockring that comes with your cassette – TacX includes two unique locking rings either for t12 or t11 toothed gears on the final cog of your cassette. The requisite spacers for 10 of 11-speed cassettes are included, along with a small washer to allow for use with bikes with distances greater than 130mm between the chain stays

Tacx Flux

At this point, your set up is just about good to go but let’s complete the walk around of the unit before we get onto the riding.

On the side of the Tacx Flux, we have the three indicator lights, confirming that things are running nicely, from LEFT to RIGHT, Bluetooth, ANT+ and the power indicators

TacX Flux

Speaking of power, as mentioned the Flux has an integrated power adapter, which I’m quite pro. Given that the Flux is very much a device to be setup, and left alone, I like the single kettle lead. It makes it much easier to buy an extension (if needed) in order to properly install the Flux and cables in your pain cave. There may be some people who don’t like the idea of an integrated transformer, but I know vastly more people who have lost power packs for devices, rather than had them die!

The internals are 110-230v so you’re going to be able to get the unit shipped from anywhere you can find the cheapest deal/supplier (I’m thinking about Oz and their ridiculous prices for trainers)

TacX Flux

It might not seem much, but given the internals, I was desperately hoping that the Tacx Flux would copy its big brother, and be able to run without power. We know it doesn’t have downhill drive, so we wouldn’t theoretically lose anything. However, that is also something which has been dropped and may be connected simply to generation ability, with the Tacx Neo containing 32 magnets, vs 8 in the Flux.

Carrying on the tour around the Flux, on the LEFT side of the unit is the spinning side of the Flux’s flywheel, with the warning on the side, stating “Caution gets hot”

TacX Flux

I’m a little surprised at this, given the release of the Cyclops Hammer, where everything is enclosed and can’t be interfered with by little hands after or during a session.

At least on the Neo, the spinning parts are on the same side was the cassette, but then again we are also looking at a virtual flywheel here, rather than a spinning chunk of weighted metal

TacX Neo vs Wahoo KICKR

Flipping the Tacx Flux over, there are 5x7cm pads on the edges of both feet,

Tacx FluxOn the rear foot of the unit is also a wider, but shallower rubber grip

TacX Flux

Tacx Flux Specifications

TacX Flux

So Tacx have taken a machete to the price of a direct mount trainer, but what do we loose in exchange for a slightly healthier wallet, and does it make financial sense?

  • Dual compatibility for both Shimano and Campagnolo cassettes via EDCO free Hub
  • Communications: ANT+ FE-C and Bluetooth 4.0 technologies. Corresponding LED on the side
  • Max Wattage: (at 20mph):1500 watts (2200 watts for Neo)
  • Max Incline: 10% (25% Neo)
  • Max Torque: 22.1NM (85Nm Neo)
  • Max Brake force: 65Nm (250 Neo)
  • Magnets: 8 (32 Neo)
  • Flywheel: weight 7kg, simulated to 22.8kg (125kg Neo (simulated))
  • Foot Print: 670x650mm (750x575mm Neo)
  • Height: 465mm
  • Weight: 16kg (21.5kg Neo)
  • Noise: Tacx have not released their specific levels here
  • Output: Speed, cadence, power
  • Accuracy: +/- 5% power readings (2% Neo )

With that, we’re probably nearly really to go for a spin!

Using the Tacx Flux

Whilst there is no calibration function needed on the Neo, that is a requirement for the Tacx Flux. So before actually going for your maiden spin on the unit, you’ll need to download the Tacx Utility App

TacX Flux

From here you can update the trainer to the latest firmware before your calibration

TacX Flux

The calibration is performed via a spin down in very similar way to that of Wahoo approach, spin the unit up, to 30km/hr and let it coast down
 TacX Flux

TacX Flux

The calibration can be performed over Bluetooth with your phone, but also over the ANT+ FE-C protocol. In both cases it would be nice in the future of Zwift was able to offer a calibration button before you completed the login process.

So with everything plugged in, updated calibrated, it’s time for the Zwift Gear Test!

Tacx Flux Zwift Gear TestTacx Flux

It should be pointed out again that this Tacx was used at ZwiftCon over the weekend before this review. HOWEVER, it would not have done more than 200km across the weekend, which should not really be enough to explain what follows…. (My KICKR, for example, has at least 4000 km on it, and we have had no reports of issues from the other turbos used at the event after)

During the ZwiftCon event my experience of the Flux, specifically the inertia, felt very reasonable and tackled the hills well

The unit seemed well planned, but it is worthwhile noticing that the Tacx Flux does have a narrower foot profile than the Neo, the nature of the build means it is very much a fixed dimension,

TacX Flux

The unit did feel a little…I don’t know…less planted that the bigger Neo. More likely a facet of the narrower wheelbase on the Flux, as I could get a slight wiggle from the feet if standing out of the saddle on the climbs. It should be noted with that there is no when in the stabiliser in the box, as the Flux axel is at the standard 34cm road bike height. So not needed, and thus omitting a stabiliser/riser is a reasonable way of reaching the lower price point

TacX Flux

Pushing around Watopia, some of the simple stats from the Flux do come into play. The 10% ceiling on climbing height being a point. On the taller mountain climbs, you are going to max out the trainer before you have actually crested the hill – here pushing 13% on the way to the top of the mast. The vast majority of people won’t mind a jot, but it is worthwhile thinking about it, if you are a mountain goat!

Tacx Flux

Taking things through the esses on Watopia gave smooth power return, and resistance response, but whilst smooth I would sometimes feel a fraction of a delay, the climb seeming to bite just after my rider has started on the up hills, but this is something most manufacturers have seen and dealt with over firmware, but definitely something to watch for. I also noticed an occasional sound coming from the turbo, but only really audible when coasting, I couldn’t manage to record it on my phone, so just left it be, and assuming it was something I had missed when testing the unit earlier.

Tacx Flux Powermeter

Let’s take a look at the power readings we’re getting when using the Flux. Tacx states that we’re going to be getting 5% power accuracy out of the box, which will improve to “about 2-3%” when the unit is washed up. I’m not a great fan actually imprecise information like that coming out from a  company, so we’ll call it 5% as that is what is stated in the manual, and consider that we look at the power graphs.

In order to accurately test a power meter, you need three units to compare to, so using I’m using the 4iiii Precision, and PowerTap C1 as comparators, attached to three different recording units.

Wahoo KICKR SNAPSteady state, the Flux runs exactly as you’d expect at £700 trainer to, keeping up well with the data coming through from the other power meters. But things seemed a little strange looking at the readouts from the head units when doing a few sprints on the Flux, although simply eyeballing head units isn’t an accurate way determining that

So I pulled off Zwift, to take a quick glance at the data in graph form, before carrying on. Let me assure you there is nothing worse, than doing a 20km test on a trainer, and find that something has gone wrong with a head unit, and all you have is junked data!! Been there, done that, not a happy bunny, so I have a low threshold for stopping and checking now.

So this was my first graph – Oh.

 TacX Flux

There appears to the small amount of smoothing going on with the Tacx, but that will be due to the lack of strain gauges, and the presence of a power estimator in the unit. But that isn’t the main issue as the Flux doesn’t appear to be tracking well in terms of timing, the power recording from the other two power meters coming in about 3-5 secs before the Flux is registering the power tick up. On Zwift, in a race, that isn’t going to be doing you any favours at all.

For reasons I’ll come onto in a moment, I wasn’t able to complete any more testing on this unit, but I did reach out the Shane “Llama” Miller about his experiences with the Flux, as he has mentioned a small lag as well, that he discussed in his video.

Shane, gent that he, is sent over his power data, which looked very similar, smoothed, missing the peaks of power, and demonstrating the lagging

Tacx Flux

Discussing the issue with Ray Maker over at DCR, he commented on similar findings 

It appears others are beginning to post similar comments on Shane’s video too

Tacx Flux

The Problem

I mentioned that I haven’t been able to complete any more testing, the reason being that the Tac Flux sound or a noise, mentioned earlier, go worse

Previously I wasn’t able to get the iPhone to pick up the noise, but now it is loud enough to hear when coasting the unit, I have been able to record it slightly

Chatting to Shane Miller about his unit, he has experienced a similar noise, which he road through, before properly “Fluxing” his unit. I’ll leave that story be for the time being to allow Shane to put out his experience, but suffice to say, I took his advice, stopped riding and sent the unit back, before potentially causing more damage

We did compare serial numbers, finding that turn units were 300 units apart, DCR’s serial is about 50 below mine. So in terms of further testing, we’ll have to see if things become more accurate with a replacement in terms of power accuracy, lag, or strange noises.


TacX Flux

Each turbo manufacturer is appealing for your to open your wallet for different reasons. Wahoo with the KICKR name, Tacx with the Neo advanced tech and Elite with their insane accuracy (currently trying to push 0.5watts in the labs!).

Currently, supplies of the Flux are limited, so if you do find one available, the question is “To hit the £700 price have Tacx paired something down inside the Flux too much?” If you find a Flux, should you pull the trigger on that purchase?

The Flux looked like it was going to be THE MAJOR disruptor in the turbo trainer market given the direct drive focus, and that astonishing price point. However, there appear to be a couple of gremlins in the mix currently.

The Neo had a few gremlins when it too came out of the factory, however, Neo’s from the 2016/17 model year appear to be as stable as the Neo itself is planted. I’m hoping that Shane and I have just been unlucky at the same time, BUT until we have a full picture as to what is going on and given I am currently without a working Flux to check if things have changed via a firmware update, I can’t recommend the Flux if you are thinking of competing in races on Zwift.

I’m certainly looking forward to seeing Shane’s report on when “the Flux went pop” to compare

Update – I have had a LONG chat to Tacx, and have written everything down here – there is quite a bit of info!

Tacx Flux problem issue update

About James Gill

A runner first, a cyclist second, and when pushed a swimmer. Working as a GP registrar, I found that I went from walking 12miles a day on the hospital corridors to sitting in a chair. Whilst at medical school, I'd run 10km in an evening just for fun, but having lost the general activity required to be a hospital SHO, consciously being active has now become more important - well until I broke myself!

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  • Kevin Mawdsley

    shanorrelllabradors is another account I have.

  • Bob… The Neo on Amazon are £1043 and are out of stock at the moment. Too many bad reports but was considering that next.

    I sent my Flux back even though I hadn’t paid for it. I didn’t like it. I had another direct drive trainer and sent that back as well.

    I sold my Bkool Pro over 1 month ago (after having it for 11 months and 1100+ miles), and I wanted a better trainer for the steep climbs with no wheel spin. But the new ones didn’t do it for me. so, I purchased a used Bkool Pro yesterday (£275) and it feels sooo much better than the direct drive trainers… apart from the steep climbs where the wheel spins… but I love it!

  • Bob Dynowski

    Hi Kevin, I am a bkool pro user and have just sprung for the Neo over the flux mainly for the 10+ gradients in bkool and zwift. Neo’s for £850 on Amazon if you are a UK user so not that a differential with the Flux.

  • Very good review!
    But why is there no front wheel support and the 100 € discount code for the Upgrade Smart that is together with the Tacx Neo Smart!

  • Kevin Mawdsley

    Yep… more feedback on the Hammer would be great 🙂

  • jb

    any more feedback on the cyclesops hammer. tacx crappy quality control is legendary.

  • Kevin Mawdsley

    Good review, James! Thanks for showing my comment from Shane’s video… good to know my experience of the Flux is relevant.

    I just want to point out that the comment was me using the Flux with the Bkool app and not Zwift. I’d tried the Flux with Zwift earlier and it wasn’t that good, not giving any resistance on the climbs so ended that ride and used Bkool which I’m more familiar with.

    I’ve posted some more comments about the Flux on Shane Millers video.

    The lack of noise is what I really liked about it but the racket yours is making sounds terminal if it isn’t looked at. I have boxed mine up ready to send it back even though it stills sounds sweet.

  • Rich W

    I purchased the flux last week and experienced the same grating noise. Took it back to the shop and they contacted Tacx who asked for the unit to be returned and a replacement unit will be provided. We will see if the problem persists.

  • Good read! So you’re saying that Tacx has popped out a firmware update which should fix the late response on the power readings?