Erg vs resistance

For the planned intervals, where a range is specified in the workout (ie 84-97%) and a range is provided in the TrainingPeaks workout that FastCat created, but when it is synced to Zwift, becomes a fixed power, usually in the middle of the range, is it better to use Erg mode and ride at the fixed power, or to use free ride mode, and stay in the recommended range?

I always recommend to do it freestyle. Some days you feel good and can ride towards the high end of the range and some days you don’t so you may ride at the lower end.

When you are doing efforts at FTP or higher such as Vo2 max intervals I highly recommend not using erg mode so you can ride full gas. Basically ride at the highest intensity you can ride at for all the intervals to be consistent. And when you get to intervals that are at and above FTP each rider is different so the middle of the range doesn’t necessarily work.

Some riders just do like to use erg on tempo and sweet spot efforts to just zone out and that is perfectly fine some times. But I recommend not using erg so you can train your body on putting out the effort and how to pace yourself.