I just did the Speed Sprints workout. The workout is done in erg mode, but it has 6 30 second efforts in sim mode (erg mode is switched off automatically). The goal of those 6 efforts is to do a sprint with as high a cadence as possible (and manually select the gear to find a power for which that cadence is maintainable).
When it switches from erg mode to sim mode, the gear is automatically set to 8, so I have to shift up to a much harder gear quickly while also increasing cadence as much as possible and then maintain that cadence. The issue I experienced is that there is a massive overshoot while shifting up with high cadence. I’m talking about an overshoot of 200-300 Watt, and then the power starts dropping again while maintaining cadence to the correct power for the selected gear. You can see the issue here, massive overshoot, so it hits a brick wall if I shift up quickly, as a result my cadence drops (but I manage pull through). Next the algorithm starts to recover from the overshoot, power slowly goes down to the correct power for the gear. Which is way too low. So I have to pay attention to the power going down as well, shift up, try to predict the overshoot, …, it’s a rather horrible experience doing this while trying to do a hard 30s sprint. The later efforts were a bit better than the first ones since I got a bit better at predicting the overshoot etc, but needless to say, in none of the 6 efforts I actually managed to achieve the as high a candence as you can hold for 30s at as high a power you can goal.
(pc, wahoo kickr v6, zwift ride, virtual shifting)