There is the strength that S-Class Hero Genos yearns for, the strength of ultimate physical destruction. C-Class Hero Mumen Rider possesses none of this type of strength. Riding into a fight with a monster he realizes he has no chance alone surviving from, let alone prevailing in, he charges. He charges, and charges, and charges.
This One Punch Man character’s struggles is not unlike Paranoia Agent character Misae Ikari. She faces down her own demented foe, one she can’t physically run away from even if she wanted to.
Heroes require strength. But do they necessarily require the physical kind? Perhaps superheroes do, but people like Mumen Rider has only the strength and utility of an average individual with a foot-powered bike. If he saves someone while losing his life in the process, or sacrifices himself in the attempt to, does that make him, or anyone like him, ineligible to being called a hero? Because he didn’t have the physical strength to manage it all? Is this something that something our consciences can stomach? Perhaps the strength we roundly require of our heroes isn’t the physical kind exactly, though it might be convenient if our heroes were physically tough. Perhaps its fortitude then?