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Neo 2 Linearity Update – Firmware v.34

Yesterday, Tacx announced the release of firmware version .34 for Tacx Neo 2 and Neo 2T. On top of the list was a linearity fix for Neo 2, meaning increases fidelity to a specific target watts regardless of flywheel speed.

This is an area where all versions of Neo have suffered, but Tacx was able to resolve for Neo 2T with version .31 firmware — but which also introduced the Phantom Watts problem. This firmware version now brings the same fix to Neo 2, and simultaneously reverses the phantom watts problem for Neo 2T.


In order to determine if the fix was working, we had to do some testing.

We connected our Neo 2 to Tacx Training App and set the resistance to 100 watts. We selected 100 watts because it makes percentages easier to calculate, and we are often lazy. Our bicycle was set up with 50/34 11-28 10-speed cassette with Assioma Duo pedals. Both the Assioma Duo and the Neo 2 were recording to identical Garmin 520 cycling computers via ANT+. While maintaining 90 rpm cadence, we shifted through through all the gears of the cassette, one cog per minute, starting with 34/28 and all the way down to 11, then started the next 10 minutes of testing in 50/28 and ran the cassette again.

Round One

The first set of tests was a Neo 2 on firmware version .15, and the results were pretty much what one might expect. The gap widens considerably at higher flywheel speeds, and there is little fidelity, even in the small chain ring.

Full results here:

Round Two

After the first test concluded, we updated the firmware to .34 and re-zeroed the Assioma Duo. Unfortunately, there was a ten second ANT+ dropout from Neo 2 in the middle of testing, but we weren’t going to conduct the test again for fear we’d be in an infinite cycle of potential dropouts and because screw that. It’s our absence of standards that many admire.

Full results here:


Although there is a significant improvement, there is yet work to be done. It’s absolutely better, no question about it, particularly in the small ring where there is generally less separation between the Neo and the Assioma.

It will be interesting to hear the results from others, and for how many people who’ve reported Neo 2 underreporting power compared to another PM, how this firmware update shifts the outcome.

If you’re on the fence about updating, this is one you should consider. Green light from Tacx Faqx.

Updated on January 30, 2020

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  1. Hi Tacx team,

    I just updated the firmware to v.34 to my Neo 2 Smart trainer, however, after the update, my trainer is unable to connect to my zwift using bluetooth. My Zwift app is installed in mac OS Catalina version 10.15.3.

    Before I upgrade the firmware (used to be v.32), zwift and my neo 2 smart trainer is working fine.

    Please help as I just realised this firmware update is quite recent. I should have wait longer before doing the upgrade.


    1. Hi Vincent. If you’ve just done a firmware update, you need to make sure you have disconnect your trainer from the Tacx Utility App before attempting to connect to Zwift. When in doubt, check the bluetooth LED on the non drive side of Neo. If it’s illuminated, then you’re already connected to another app or device and will need to disconnect before attempting to pair with Zwift.

      There is nothing in this update that would otherwise affect the bluetooth transmission.

      1. Hi Drew,

        Thank you so much for your advice. I have followed your suggestion and it is working fine.

        Many thanks and great help from you, Vincent

    1. That is an odd question. Are you concerned?

      I’m not sure what you mean specifically, but I will say there will always be accuracy concerns with every trainer, and that by and large, Neo is regarded as the pinnacle of current achievement in the industry. What else can be said?

      1. I guess there is, I have a neo 2t but previously had a kickr first gen and always used my infocrank as the power source but wanted a trainer that I could rely on with out having so many things connected, I see lots of people reporting that the neo2t is under reporting power

        1. I had a Neo 1 which was totally in sync with my Garmin Vector 2 pedals. I have just replaced Neo 1 by a brand new Neo 2T (Fw 0.34) which is now underestimating power by 10% vs Garmin Vecor 2 !!! So I now have to use Garmin Vector 2 as Power source on Zwift which was not the cas with Neo 1

  2. I guess there is, I have a neo 2t but previously had a kickr first gen and always used my infocrank as the power source but wanted a trainer that I could rely on with out having so many things connected, I see lots of people reporting that the neo2t is under reporting power

    1. I’m always skeptical when someone tells me their Neo is underreporting because we have done so much research into this with respect to drivetrain losses that few will account for. They expect their power meter and trainer to read exactly the same, but that is impossible with our current understanding of physics. I’m happy to accept results if someone can provide a different model of physics, or evidence that physics do not apply to them because they are testing their bike in an alternate universe.

      That said, I still feel that the champion is the original Neo. The calibration issues that were abundant with Neo 2 don’t seem to have trickled down to Neo 2T. Unfortunately, we don’t have enough Neo 2T units to test them methodically.

  3. anyone can advice when will the rear fan rans? after i plug it on power source only the fan located near the BB rans and the rear unit doesn’t, is this normal or will it ran by itself?

    Thank you..

  4. I am trying to update the firmware. I’m using Samsung note 9. The device shows connected, but when I try to update, it gets stuck on “Entering Bootloader”

    1. Bump…also interested given that I am seeing 4 to 5% under reporting on my Neo2 compared to Assioma (I’ll be generous and allow 2-3% for drivetrain losses – so in my book it is underreporting)

      1. 2 – 3% would not be generous. It would be miraculous. Under ideal lab conditions, the BEST result that Ceramic Speed were able to produce was 3.2% using only mineral oil as the lubricant. My guess is that your drive train is somewhat less efficient than those tested at the lab. To me, 4% is entirely acceptable.


        That aside, Neo 2 definitely has a storied history of under reporting, such that Tacx requested multiple units to be returned to Netherlands for recalibration. It is entirely possible that yours is one such, but 4 – 5% is still in the range of “normal”, so you will need to provide additional evidence to support your hypothesis.

  5. When I received my new Neo 2T I updated the firmware to version .34 and cannot see the pedaling dynamics information. A clubmate bought another one a few days later and without updating if he has that information.

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