I have it set up just how you’ve listed - connect the Stages Bike as a controllable trainer, and do not connect either of the crank arm power meters.
I have run mine a bunch in resistance mode for TR workouts, but I always need a secondary app for shifting - there may be a way to do it only in TR but I haven’t figured that out yet. I am usually dual running Zwift whether in erg mode or not, and to use TR in resistance mode I:
- Load up the workout in TR on my iPad (Bluetooth), connect to the bike and my HRM, and then switch the SB20 to resistance mode in TR.
- Start Zwift on my PC (ANT+), and make sure to set the SB20 as a controllable trainer.
- Using this setup I can change gears with the bike’s shifter buttons, and TR records the higher / lower resistance and power.
When I am using TR in erg mode I definitely want Zwift to have controllable as OFF, otherwise they will fight over the power level - this is only the setting for non-erg training.
There may also be ways to do this with the SB20 app and not need Zwift, but given that I’m usually running it anyways this is the setup I’ve configured.