Reminds me of the Chinese issue: you run over someone, but they are likely not dead. Will you save their life but accept having to pay for whatever healthcare costs they have until they are recovered? Or will you run over them again, to make sure they die and your punishment will be a lot lighter?
A fun toy. But a normal exercise bike already converts the energy to heat. This heat then warms up the apartment.
Of course, with electricity, a heat pump for heating or cooling could be used, which is more efficient. But it’s not like the energy remains unused with a normal exercise bike, as long as it is cold outdoors.