The Tacx Flux S – A new casing, redesigned leg setup, & a series of new copper internals replacing older aluminium innards… AND a low price!
Tacx Flux S Trainer Review | Zwift Gear Test
The Tacx Flux S looks very similar to the Tacx Flux, but the littlest direct mount trainer from the Netherlands has had a thorough reworking. With Tacx having dropped the price further, is it enough to unseat the Elite Direto from the crown of the best budget buy?
It has been a busy 2018 for the team at Tacx, they have been working hard to get the Tacx Neo Smart bike out of the door, updating the Neo to Tacx Neo 2, bringing the Tacx Flux 2 to market, and giving the original Flux a spit and polish to give the Tacx Flux S, which I feel may be a touch more disruptive to the market.
It was an open secret that the original Tacx Flux had a slightly troubled birth, while those issues were resolved with the initial Flux, it may be one of the reasons that we do not see a whole boatload of additional features – such as the integrated cadence sensor included with the Tacx Neo 2. We are getting a significant overhaul of the internal components.
Right down to the level where we see the change from aluminium to copper components to improve the experience of using the Tacx Flux S
This change has not merely been made for an aesthetic reason; you can barely see the copper disc even when you open the unit up
The change is actually related to Tacx trying to get trainer spec sheets to better display the truth behind the riders experience of using a trainer. Which can basically be summed up as how slow a rider can cycle, and still have the unit apply sufficient braking force to simulate a hill. The slower a cyclist can do, the more powerful the brake, and “better” the trainer
Unfortunately, Tacx wouldn’t allow me to take copies of the trainer curves when I popped to the factory showing all the trainer curves. I have managed to find an OLD trainer resistance curve to get an idea as to what I’m going on about
So the maximum gradient that the i-vortex was able to hit was 7%. BUT that 7% gradient was only possible at certain speeds – THIS is the crucial bit
Each trainer will have a profile showing the minimum resistance, or gradient simulation it can simulate at a certain speed. So on the above graph, the i-Vortex can produce a 7% resistance, up to about 23kph, and 270 watts. As this related to the strength of the brake. On the i-vortex the brake was an electromagnetically generated 11.81kg, so with the above graph, if you went over about 300 watts, you’d overcome the limited brake strength. By about 500 watts, the unit would only be able to generate 3% gradient.
So how does all of this relate to the copper plates inside the Tacx Flux S?
Using copper results in a much higher braking resistance, in fact almost apply three times the braking capacity at low speeds of the original Tacx Flux – so you’ll be able to simulate the 10% grade at the lower speed. There also the secondary benefit of using copper allows a much higher flywheel effect. Tacx claims that this means the Flux S has the highest inertia of the current flywheel smart trainers on the market. (I think that noise was the sound of a dutch challenge being thrown!!
Aways from the material science of smart trainers, the most apparent changes to consumers will be the tweaks to the casing… which are actually somewhat subtle
The most obvious being the repositioning of the legs to accommodate longer rear cages. You can see that the older Tacx Flux stands “taller” – however the hub, and the top of the casing remain at the same height
However as a personal peeve – in spite of the significant redesign of the case, 1mm couldn’t have been shaved off the bottom to allow the Tacx ANT+ sensor to slide perfectly underneath?? As a side note, without a doubt, if you are using ANT+ the Tacx “tank” as I like to think of it is the best antenna out there. It’s a block of resin! I’ve destroyed too many simple USB dongles with cleats, this thing, just doesn’t care!
OK, so we know that the case has been redesigned, so let’s have a look around inside the box, and see how the unit looks
Tacx Flux S Trainer Review – Design
Opening the box, we’ve got the ancillary gubbins to allow you to put the trainer together. We have the 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 Tacx FLux S legs 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!
The legs on the Tacx Flux S are very separate, and a very discrete component in the box – they are steal encased in plastic, and as a result are not very light.
It is worthwhile noting that the plastic underside of the Flux S legs, had come apart in transit, but that was quickly pushed back in.
The legs are installed by siding them into the open socket on the Tacx Flux S
Some rather chunky bolts go through the plastic cover previously mentioned
Tacx has decided to change the base colour of the Tacx Flux S, a small change, although not as eye-catching as the blue bases of the Tacx Neo 2 and Tacx Flux 2
While Tacx has opted for a completely fixed design with no facility to fold the Tacx Flux S up – the legs NOT amenable to regularly being removed from that metal and plastic sandwich, I’m surprised with the case tweaks, a handle did not appear. Sure the Elite Direto handle isn’t really the last word in ergonomics, but it’s better than nothing!
The lack of the handle on the unit, anywhere, reinforces the view that Tacx intends you to set up the Flux S and leave it standing.
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. Thankfull there is no return to the hybrid hub with the Tacx Flux S, sporting the more common Shimano hub.
At this point, your set up is just about good to go but let’s complete the
On the side of the Tacx Flux S, we have the three indicator lights, confirming that things are running nicely, from LEFT to RIGHT, Bluetooth, ANT+ and the power indicators
Speaking of power, as mentioned the Tacx Flux S has an integrated power adapter, which I’m quite pro. Given that the Tacx Flux S 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) 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 best deal/supplier
While the simulation has slightly been improved for the
Carrying on the tour around the Tacx Flux S, on the LEFT side of the unit is the spinning side of the Flux S’s flywheel, which has now changed from a smooth to a sandblasted finish, which remains to look MUCH smarter than the previous unit
Tacx Flux S Trainer Review – Specifications
While the externals might be a case of spot the difference, let’s check out how things have altered on the spec sheet
- Communications: ANT+ FE-C, Bluetooth smart trainer control – but not FTMS as this is not finalised yet, expect a software update when that is locked
- Max Wattage: (at 20mph):1500 watts
- Max Incline: 10% – Flux 2 is at 16% and Neo 2 25%
- Max Torque: 22.1NM
- Max Brake force: 65Nm
- Magnets: 8 (32 Neo)
- Flywheel: weight 7kg, simulated to 22.8kg
- Foot Print: 670x650mm
- Height: 465mm
- Weight: 16kg
- Noise: Tacx have not released their specific levels here
- Output: Speed, cadence, power
- Accuracy: +/- 3% power readings – improved from 5%
With that, we’re probably nearly really to go for a spin!
Tacx Flux S Trainer Review – Using the Device
Due to the nature of the flywheel with the Tacx Flux S, it is very important before you go for your maiden spin on the unit, download the Tacx Utility App and calibrate things
The calibration is pretty standard, spin the unit up, to 30km/hr and let it coast down
You can perform the calibration in Zwift if you select the Tacx Flux S as the power source as well as the trainer.
Hit the highlighted spanner icon, and off you go to calibrate
I do think it is worthwhile doing the FIRST calibration on the companies own app, as you’ll also get a notification as to whether there are any new firmware updates. Other than that, you don’t really need to calibrate unless moving the units.
So with everything plugged in, updated calibrated, it’s time for the Zwift Gear Test!
Tacx Flux S Trainer Review – ZWIFT GEAR TEST – Sound Test
So first things first. With a trainer, we need to know how noisy the Tacx Flux S is. It’s apparent that we’re not going to be getting sound levels as low as the Tacx Neo 2, but we should hopefully find things in the ballpark as the Elite Direto
Same setup, as usual, iPhone using dB pro, with the microphone set up pointing towards the trainer. Cycle up to ~ 700 watts and coast down
So here’s the video!
Let’s look at the data away from the video, as you can see the Tacx Flux S has a note is relatively coarse, but not significantly different from the Direto. But with both trainers, don’t try and put sleeping babies in the next door room!
Tacx Flux S Trainer Review – ZWIFT GEAR TEST – General Riding
Now I’ve been mainly riding the larger trainers, Tacx Neo 2, Elite Drivo 2 and the Wahoo family of late. When the Tacx Flux was released, it felt like quite a planted trainer. Compared with the other trainers on the market, it is noticeably easier to move from side to side. That’s not to say I felt as though there was even a remote chance of me knocking it over, more a reflection of how far the field as moved.
pushing around Watopia, some of the simple stats from the Tacx Flux S do come into play. The 10% ceiling on climbing height being one of the major points. On the taller mountain climbs, you are going to max out the trainer before you have actually crested the hill – with the steepest gradient on Zwift you’ll encounter being 18%, you are actually going to be missing out a good chunk of the action – on the stat sheet
Huh, what? Surely missing out is missing out, isn’t it?
As discussed in the Wahoo Climb review – the default setting of zwift is 50% trainer difficulty, meaning even in the 18% NYC climb, the trainer is only ramping up to 9%. Yes if you want ultimate gradient simulation, you’ll not get that here, but 90% of riders never change their Zwift trainer difficulty anyway, so you’re likely not missing out!
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 uphills, 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.
In the Tacx Flux S box is also a 1-month premium subscription to the Tacx Desktop app.
Now Tacx is working to develop their indoor app to complement their trainer line up. The problem is, the software doesn’t have the community that is present on Zwift. As a result, Tacx has had to go a different route, producing up to 4K videos of well-known cycling routes. BUT I think the secret sauce is the ability to user generate the route, and rather than just stare at numbers on a screen, the Tacx Desktop app can model your route against a 3d rendering from Bing Maps
Admittedly you get a better experience in the cities where the maps are more developed, but I feel that this is indeed one aspect of training which is not covered by Zwift – essentially IRL course training.
However, I don’t think that the Tacx Flux S is the best unit to use with the Desktop App. There a distinct element was the immersion is different to that of Zwift, which the Flux S cannot address. The Road Feel on the Tacx Neo 2 however, can bridge that gap more easily. I’ll be interested to see how things develop further here, especially if Zwift cycling hardware rumours pan out, essentially putting Zwift and Tacx as direct competitors
Tacx Flux S Trainer Review – ZWIFT GEAR TEST – Power Meter Test
Moving on to the power meter test, which is what many people are interested in on for a turbo trainer. As ever, power meter testing is done using the latest Zwift build and using the Jon’s Mix workout, so we have a consistent benchmark between all the different turbos which have gone through Zwift Gear Tests on TitaniumGeek
Here the power tests have been performed against the PowerTap C1 chainring, and the Garmin Vector 3 pedals, both of which we know correlate well with all other power meters which have been through the TG testing and thus can be considered reliable when compared to a third power meter in a turbo. I’ve also thrown the Magene Ridge power meter in the mix, as I’ve been testing that, and finding some odd numbers
Now I’ll be honest, I’ve written this a little out of order. As the Tacx Flux S does need calibrating, I decided to do the first power meter test, uncalibrated, for interest’s sake.
NB I’ve applied a 4-second smoothing to the data, which can be useful in highlighting subtle issues in the graphs
Um… that looks a little bit like a dog’s dinner. I calibrated everything immediately after to repeat the second test so that all other conditions were equal.
Phew that’s a LOT better – sure the Magene Ridge is still acting as a significant outlier, but the Tacx Flux S is much more in line now
The biggest thing to notice is that the Tacx Flux S is showing a little more smoothing compared to the other power meters. I’m not too fussed there, as we are dealing with a 3% variability unit which is at the end of the drive train. Perhaps a touch smoother than some of the other trainers which have been tested lately. But that feels a little unfair, as the Tacx Neo 2 and the Elite Drivo II are actually running at <1% variability.
The Tacx Flux S does appear to ride slightly high on the steady state sections, but I do wonder if this is more a facet of the smoothing as during the sections under load, I do not see significant variation from the Vector 3’s
Tacx Flux S Trainer Review – Conclusion
To my mind the Tacx Flux S suffers from being “the youngest child” – I know it’s not chronologically the youngest Tacx direct drive unit, but it is the cheapest. That presents a bit of a problem. At £549, the Tacx Flux S is coming in around £100 less expensive than the Elite Direto, to which it is so often compared. That’s a touch unfair, as for that additional money, you are getting a grade higher trainer.
The Tacx Flux 2 is designed to take the fight to Elite Direto, and Wahoo Core in the mid-range. The Tacx Flux S is almost disadvantaged as it doesn’t have a direct competitor. As a result of which, I’m really on the fence. I feel that t the Tacx Flux S deserves a 3/5 rating, as it has a series of tiny limitations compared to competitors ALL OF WHICH COST MORE. The Tacx Flux S is punching above its weight, sure the more expensive turbo trainers, are going to take its lunch money, but it’s still a damn sight smaller/cheaper than they are. So based on price as much as anything I’ll give 4/5