I suspect that "most people" even includes the guy who sprinted at 27.8 mph. The crank lengths and gearing are all wrong on a bike for an explosive sprint, preventing all the right muscles from being recruited to the job. No matter the speed and gear, your feet are constrained into spinning around the same smallish circle. And wile you can use your whole body in order to sprinting on a bike, it's not the same like when a running sprinter uses their entire body.
Mmmhh, not sure about that. Most people, even if not reaching high speeds, can still go substantially faster on a bike than running. Even grandmas, it's all relative.
People like Bolt should be compared with bike sprinters, who top out at around 45mph.
“His thighs were measured with a circumference of 73 centimetres (29 in). A circumference of 86 centimetres (34 in) has also been recorded, and the size of his quad muscles has led to him being called "Quadzilla" by some in his sport.”
That's definitely not true. You can sprint explosively on a bike, you just have to get up and push your legs down on the ground. Since your leg is at 90 degrees you can exert maximum power. I've done 50kph on the flats on a bike, it's not that hard; far easier than on foot!
