Unfortunately I don't have the tools to do that.

I did another test today with the Wahoo bike fit assigned as a "Race" fit. It made no difference to my Wahoo reported bike speed so I guess the Wahoo aero model is fixed. The only other parameter in Wahoo is my height, so I will see if that has any effect on the aero model.

This got me thinking about how trainer resistance is actually set when using Zwift and similar apps. I presume Zwift only broadcasts the slope value and the trainer then applies resistance based on its own physics model according to the broadcast slope value. That's how it seems anyway. I checked my simulated gear ratios too and they correspond perfectly to the Wahoo bike speed. Obviously Zwift speed is set by power and their own physics model, which in this case is much faster except when climbing at very low speed.

The Zwift ride I did today was the Ven Top climb. Average power reported by Wahoo was 201 W vs 206 W on Zwift. Much closer than my previous comparison because there was very little coasting. But Zwift did still manage to find me a free 5 W . Average speed on the climb was within 1 kph except for the flatter sections, where Zwift was as much as 4 kph faster at times.

I still think the Wahoo model is a bit slow compared to real life, but much closer than Zwift, which is silly fast on the flat and descents. But I always knew that was the case with Zwift and ultimately it doesn't matter how fast the Zwift avatar moves. It would be nice if the Wahoo physics model could be tweaked for aero and rolling resistance to match real life, but that doesn't appear to be an option. It does feel like I'm riding into a headwind on the flats!