Zwift Hub - AutoCalibration in Trainerroad


My Direto just “blew up” and the most available alternative was the Zwift Hub, so its now standing in my paincave for couple of days.

Beside that well known SpinDown-Calibration I would like to use the relatively new AutoCalibration - it sounds more practical in general. However, based on the instructions its not running in ERG-Mode and just during freecoasting.

As there is practically no freecoasting during TR-Workouts I would like to ask if anyone has done this, has a workaround or else.

Thanks a lot!

I don’t know the specific time requirement for the spindown here, but there’s no reason you can’t still coast in ERG mode. Just stop pedaling, let the trainer spin to a stop (assuming that’s the calibration requirement) and then restart pedaling.

TR’s “soft start” mode within ERG will make it easy to get rolling again. I’d generally recommend doing this during the low part of any workout, likely after the warm-up section which will get the trainer to operating temps.

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OK, I wasn’t clear on that being an actual Hub limitation.

ETA: A hack could be to simply swap modes to RES within a TR workout, do the coast & spindown and then return to ERG. That is quite easy on Win/Mac via keyboard shortcut (‘T’ IIRC), but a bit more of a hassle for mobile which requires diving into the trainer at the Devices screen.

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Thank you, guys.

Yes, its a fumble to do it on the mobile (which I´am using) but its seems to be the only way. Have forwarded a user request to TR long time ago to have the switch simplified, but …

@mcneese.chad Whats this “soft start” mode within ERG? Havent heard of this so far.

@Dougal.Doughnut My Hub just three days old and the unboxing was a bit disappointing (missing washer, bent cassette). Hope the next days on the trainer will be more satisfying. Btw: 10mph for auto calibration just refer to the freewheel as far as I know so its not that clear to me how much input is needed to accelerate the freewheel for the auto calibration. Probably not much but will it be 50W, 100W, even more? Would love to see some kind of feedback on screen or on the trainer light once the auto calibration was done successfully.

  • I can’t seem to find a link quickly, but it essentially “eases” the ERG resistance level up when you are starting from a dead stop. It is a feature they added a while ago to make restarting after interruptions (like stopping to grab something you forgot, answering the door or other reasons you may stop pedaling or get off the bike) easier than hitting that instant “wattage wall” of the prescribed workout target.
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I got some interessting feedback from the Zwift Support on this:

Auto-Calibration in ERG-Mode, even pausing / stopping the ERG-Mode and switching to freerid/slope, would not work due to technical limitations of the hub. One point mentioned was due to high temperatures raising while having pedalled for some time in ERG-Mode.
In reverse I asked what ideal watts should look like if ERG-Watts are to high and to my surprise they stated around 100W (for each, Spin-Down warumup and Auto-Calibration).
I dont know when my ERG-Warmups were around 100W but good to know that even a TR-Workout-WarmUp might be to intense for the trainer.

I also asked TR-Support what their recommended Watt is for TR-App-Calibration and they also confirmed about 100W. (For trainers in general, not specifically asked for the Hub.)

Hope this additional information helps.

Edit: Just saw that the other guy who participated here deleted his posts … okay, maybe some other users might benefit from the support feedbacks :slight_smile:


Tried yesterday first TR-Workout on the new trainer and it was going from 157W to 298W within 2 secs (or less) :sweat_smile:.

An “improvement” compared to my old trainer who took around 7-10secs for a comparable jump in watts (especially for shorter interval bursts), but I would not call this “soft start” mode. Pretty tough imho.

The Soft Start in ERG only applies when you are restarting from a “dead stop” where neither you nor the flywheel are spinning.

It sounds like you’re describing typical trainer lag that happens when switching between power targets. Each trainer has some amount of lag and it differs a bit between trainers. This ERG Soft Start has nothing to do with that timing or feel.