It seems, that the cadence guessing of the Zwift Hub One is pretty bad, directly affecting the power values. Still fine for me, if adding a cadence sensor solves this problem.
That’s very interesting but puzzling. Usually power measuring devices are reporting already computed power over ant+ or ble which means they have done their own internal maths or whatever estimations some trainers do. An external cadence sensor would not affect those. I was also under the impression that trainers don’t have cadence sensors (they can’t directly measure your pedal rotation, only the rear hub/cassette) but they derive cadence from the fluctuation of the torque during the pedal cycle, hence it’s not always very reliable.
I will try to give it a go before I sent it back. Zwift is replacing mine, I presume mostly because of the loud grinding noise and not because of the readings.