I’m doing the dirt Destroyer training plan and a few times when it asks me to do higher power, low rpm segment it’s like the trainer (Tacx Vortex) can’t provide enough resistance. For instance 340W @ 65 rpm in ERG mode. I have to shift into my highest couple of gears to get there. Typically I ride the big ring and the middle of the cassette, but if I sit there at 65rpm it can’t or won’t put out 340w. I have a hard time thinking I am somehow overpowering the trainer or something.
Welcome to the forum.
All trainers have a power curve and band where they operate the best.
The band will look something like this, were the green is where your trainer operate the best.
Power (w) on the Y axis and Wheel speed on the X axis.
So for the trainer in the chart you have to have a wheel speed between 20km/h and 50km/h to be in the zone.
So depending on your gear ratio you may need to shift to be in the correct zone if you want to ride at 65rpm.
The image below show some tipical gear ratios, the green is gear ratios the will give 20km/h at 60RPM
So if you want to do low cadence you have to be in a big front ring and small cassette.
Makes sense, thanks for the thorough reply!