Here’s a simple way to add some interest to long AER rides on the trainer (or rollers in my case):
Divide the total duration of the ride by 5.236. This is your shortest (and final) interval. Take this value and multiply by 1.618 (phi, or the Golden Ratio). This is your second interval. Multiply the second interval by 1.618 to get your first interval. Program the first (longest) interval at 66% of CP, the second at 70%, and the third at 76%. In practice this will result in an average power / IF right at the target for AER rides (.69), but create a bit of interest and allow you to progressively work through the aerobic zone.
Example
duration = 204
t3 = duration / 5.236
t3 = 39
t2 = t3 * 1.618
t2 = 63
t1 = t2 * 1.618
t1 = 102
In this case, I would ride 102’ @ 66%, 63’ @ 70%, and 39’ @ 76%. Screenshots attached.
