Yeah, so the zero options on the Powrlink pedals are:
A) Manual Zero Offset: This is pressing the ‘Calibrate’ button manually from most bike computers/watches/etc (or, the Wahoo app)
B) Auto Zero: In this case, it’ll trigger as noted above, but that’s basically a scenario where you have it sitting still by itself. Any load (including being clipped in), won’t trigger it. So a trainer won’t trigger it, but it will trigger if you leave your bike on the trainer. It’ll happen within 30 seconds of no load/upright. Wahoo says it’ll even pull this off at traffic lights if you’re not clipped in. This can be enabled or disabled at your choice, by default it’s enabled.
Then there’s the static calibration (hanging weight test) - that is not supported here.
Note that all of this is different than active temperature compensation, which this has as well.
In terms of zero offsets go, I think we’re pretty much long past the days where turning off auto-zero is a good idea. I just don’t see leaving it on as an issue in any of the testing I do. I think this is really an older-school SRM philosophy that almost always ends in tears on newer units that are simply far better at it than almost every human is. In my testing, I left it on, and it nailed it, across vast conditions and differences.
Still, I like to manually zero (zero offset) at the start of a ride and 15 minutes in. Mainly for my own testing purposes so I know everyone is on the same playing field.