Hub Trainer Erratic Power Readings [October 2023]

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Wondering if anyone had this sort of issue happening to them recently? (see video on reddit)

/r/Zwift/comments/1707n1w/comment/k3jihgk/?context=3

Started Zwift (I am on zwift hub trainer) after a few days and the power readings are going totally crazy. No difference if I put it on 3sec average.

The tool wrench that usually is available to calibrate the trainer only shows up for a couple of seconds before misteriously vanishing. When I manage to click on it before it goes away the trainer is unable to connect.

Un-installed, installed again the app. No changes. I have no idea if there was an update because I wasn’t in front of the tablet (android) after I started the app. Current version 1.49.0 (121395)

Power shows up just fine on my Garmin so i know it’s not a Hub issue.

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@Gabriel_Mendes_Da-Co your power reading fluctuations look similar to mine, and I can see you are on the latest Hub FW 5.2.0. A couple of things to note:

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I’m also experiencing the same and have logged it with support.
Regardless of whether I have 3s Average or Instantaneous selected, the watts displayed are erratic. I tried the hub in another cycling app and did not have the issue so I think it is game related.
It doesn’t matter if I use the PC, iPhone, companion etc…

It may be my perception because of the visual feedback, but the flywheel feels different and I seem to be getting less watts for the same effort. (but I can not verify that until I try a race)

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Hi Gabriel
Turns out we’ve just been upgraded to 10hz Race Mode.
Zwift announced this today and means our power numbers are updated more often and therefore the Avatar is more responsive. :slight_smile:

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For the record, we don’t call it Race Mode - that’s what Wahoo calls their implementation of 10 Hz power reporting.

What it means is that the Zwift Hub trainer now broadcasts your power data 10 times a second (10 Hz) instead of once a second (1 Hz), so your avatar will respond more quickly in game. Be sure to update your firmware if you haven’t done so already.

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Thanks Shuji, nice update - and now I know what’s happening with my trainer.

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We’re looking into this point you raised.

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Thanks. By the way, now I know that the 3s average is still a moving 3s average, but being updated 10x a second, I’m ok with it and finding it nicer to get more responsive feedback. I wouldn’t want to go back to updating every 1s but maybe somewhere in-between.

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Hi, I wouldn’t have expected watts to be jumping all over the place if 3sec average is enabled? This option appears to have been disabled with the introduction of the increased frequency rate. However, it looks like I’m in the minority as most people on this thread seem to prefer the instantaneous watt output. Cheers.

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If wattage readings are bouncing that quickly, isn’t it difficult to try and match a wattage target when doing a workout?

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Steve thank you for this forum thread. I had the same issue as well starting Oct 3. Now I understand why it seems the 3 second power appears to be instantaneous power reading. I did all the same steps you did, and my firmware is up to date.

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Happy to help. I’ve also got a video of it in action on YT while reviewing the Zwift Click

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Hi all ,

I used my Zwift hub today for the first time since the update.

At first I thought it’s going crazy or broken.

So ended up doing a short ride for the tour.

Then searched the internet and found this thread.

Thank you guys for this , now I know that it’s “normal” to see the power to jump that much and being all over the place.

Now just have to get used to it :see_no_evil:

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Zwift game version 1.52 addresses this issue on trainers capable of broadcasting power at 10 Hz. Please update when the phased rollout is available to you.