I'm not sure what there is to discuss.
FWIW, this is how I do trainer and roller interval sessions. I don't use a heart rate monitor or powermeter or anything, I just pick a cadence and gearing that has me feeling the right amount of pain, then use the speedometer to maintain wheel speed, and therefore, my power output, constant over the interval. If my speed starts drooping, then I know that my power output is drooping, and I need to step it up.
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --
the tiniest sprinter