> another way to phrase that is that it is less exercise
Biking is less demanding on some parts of the body that only can take so much stress. So you can push other parts more if that makes sense: top cyclists can do 400-600 W sustained or 1-2 kW in short sprints. That's not less exercise, that's several times more than a walker or runner can do. So in the same time as walking you can either be faster at your destination and save time and/or energy, or go further while spending the same or less energy, or output more energy. The choice is yours.
Anyway, from the CO2 perspective, biking vs walking is splitting hairs really.
> Top cyclists are doing it as a sport, not as a means of transport.
Well you were mentioning exercise, so I reacted to that. The point is everyone biking as exercise can push more watts than when walking, if they want to.
Biking is less demanding on some parts of the body that only can take so much stress. So you can push other parts more if that makes sense: top cyclists can do 400-600 W sustained or 1-2 kW in short sprints. That's not less exercise, that's several times more than a walker or runner can do. So in the same time as walking you can either be faster at your destination and save time and/or energy, or go further while spending the same or less energy, or output more energy. The choice is yours.
Anyway, from the CO2 perspective, biking vs walking is splitting hairs really.