Power Numbers Too Low on 2 different trainers

Hey there. We have 2 tacx flux trainers which are both reading incorrect power numbers. Watts/kg will jump from 7, to 1.2, 3, while holding the same cadence and power. The watts are generally WAY lower than they used to be (we’ve ridden zwift for years and know our normal watts.) We’ve calibrated through the tacx utility app and tried doing the same within zwift, but it gets stuck on step 3. I haven’t found any other forums or topics to help solve this. Also internet speed is not the problem as I’ve tested it multiple times.

Hey, I am new here, in fact this is my first post ever, but I hate to see technical issues impeding someone’s ability to do what they want to do, so this is going to be mostly general advice based on some assumptions (which I’ll state) in the hopes that you can do some things that’ll help fix this issue for you. I use an older Kurt Kinetic trainer, Specifically, a Rock and Roll Smart 2, so I’m not at all familiar with your gear, Your mileage (from this response), like your current watts, unfortunately, is gonna vary. Hopefully it helps. I will say upfront that you appear to be reporting two different issues: an interval polling issue where your w/kg is jumping around and a second issue in which your total wattage is down overall.

I’ll start with a question first - in your calibration step above, what is step 3? Calibrating your spindown interval?

Second (set of) question(s): When did this stop working correctly and did anything change? You mention riding Zwift for years. Are these new trainers? Did you physically move your setup? Did you add any new technology into your house / pain cave that could be interfering with the bluetooth connection between your trainer and Zwift? Have you moved the trainers closer together? Do you have any other device paired to your trainer other than the device on which you are running Zwift? Do you / your significant other have each other’s devices paired with each others phones / appleTV / computers?

Without knowing anything else, the sort of problem you’re presenting feels like it would be consistent with an inconsistent stream of data from your trainer to Zwift or potentially with some bluetooth interference.

If nothing has changed in your setup - you haven’t added anything new recently, and you and your significant other haven’t paired each others trainers on your own devices, then I would strongly recommend trying the following:

  • ensure there’s no other tech gadgets nearby that can interfere with the communication between your trainer and whatever it’s paired to for Zwift. Turn other stuff (iPads, computers, burner phones, whatever you have nearby off).
  • ensure your trainer’s batteries (if it has that - mine runs off of a CR3032) are fresh.
  • delete and re-pair your trainer with your device that is running Zwift.

Load up and run Zwift and see if you can resolve or isolate the polling issue first (w/kg numbers jumping around). Go tempus fugit or otherwise super flat area, keep your cadence flat and see what your w/kg is doing in game. If it is still jumping around, make note of whether there seems to be any periodicity to it (is it happening every 5s, every 60s, or seemingly at random).

I think if you can clear this issue that your overall watts issue may come into alignment. Before I write the rest of this novel, I’ll give you a chance to try some of this and respond with more info.