I wasn’t comparing average power against real world. I was comparing Zwift recorded average power against Wahoo recorded average power on the same indoor Zwift ride. But I do actually coast about as much as I do on my outdoor bike on similar course profiles. So on the rolling Zwift course I did plenty of coasting and soft pedalling and very little on the mountain climb. The Kickr Bike does a pretty reasonable job of replicating inertia on rolling terrain.

The only way Zwift can report a higher average power than what the bike records is if it manipulates the broadcast power data and I believe this is what some call “sticky Watts” where Zwift holds the power on for a couple of seconds whenever you stop pedalling or soft pedal. I was aware of this, but not the magnitude of it, which has the effect of boosting average Zwift power by 30-40 W on a rolling course.

When I compare the Wahoo recorded average power directly from the Kickr Bike with my outdoor power averages, they are very similar, which suggests a similar amount of coasting. I had always assumed that my Zwift average power was higher due to less coasting, but this is clearly not the case here.