Zwift hub huge change in resistance after calibration in TR PC app

I have a Zwift hub which I have been using with TrainerRoad software without issue for a few months now.

I did a spindown calibration and this resulted in a significant difference in trainer resistance, so much so that after a ramp test there was a ~60W difference in FTP.

I’m not convinced that the trainer is calibrated correctly now - I’m fairly familiar with what 150W feels like and it felt more like 220/230W!

Has anyone else had this issue? I have since updated the firmware on the Hub so next ride will see if this makes any difference.

Since Zwift added auto calibration to the hub I have not used TrainerRoad’s calibration feature, as I had similar issues in the past with accuracy.

What I’ll do is after 10m of riding so the trainer heats up, I’ll switch it from ERG to resistance, pedal at least 10 seconds, and then let it spin down until the flywheel stops. Then I’ll switch back to ERG and continue on. I usually try and do this in a rest interval to avoid disrupting the workout as much as possible.

I do this every workout and my hub is within 1 watt of my crank PM for average power, so it seems to be working well.