The ideal motor has lossless bearings and a flywheel with an MPPT converter to keep the RPM at 72 to 82% ( 76% avg) of no-load max RPM. Thus we model the engines as current sources of torque so that the power = Torque* (76% max RPM) or Current * (76% max Voc) is regulated over a range to feel light and responsive initially to get up to some inertial speed with some torque with load current such that the speed does not drop out from frustration due to excessive hard starting. The MPPT algorithm must consider the psychology of the mood of the "power source" as well as it's capacity to make it more fun. This takes impedance matching and a PID mood matching negative feedback and some fuzzy logic thrown in, to learn and adapt to changes in mood, energy level and thus dynamic source impedance. But for me, stationary exercise machines are a boring waste of time. It needs to have an immediate reward or productive work accomplished..
Although some sources of power have a broad RPM torque curve, this is not generally the case with animals or humans. Unless you are a decathalon warrior.