Your gearing isn't going to affect power output that much. You can be slightly over or undergeared and hit the same power numbers. If I were you, I would focus less on trying to dial in the wattage for the gearing, and focus more on knowing where your wattage lies in certain cadence ranges. It will be a lot simpler in the end to set your resistance for your workout this way. I'm other words, if you know that you are supposed to do an interval at X cadence, then look at your watts/RPM plot and set that as your resistance. You can gear up every few weeks as you get fitter.
Yes doing it this way requires some exploratory work, but in the end it is less hassle this way.
Last edited by taras0000; 02-25-19 at 06:11 PM.