I've been to Japan, and I saw lots of people riding bicycles there. However, they were all relatively fit. Disabled people don't ride bicycles, nor do elderly people. And almost no one rides a bicycle in a downpour. Of course, in a city like Tokyo, if the weather is bad, people can just walk their bike, or take the subway, because things are relatively close together and the public transit infrastructure is excellent. It also helps that they can just leave their bike parked somewhere if they need to, and not worry about it being stolen, unlike America where you can't leave a decent bike in a city like DC for long without someone stealing it unless you have it U-locked to a post (no one locks bikes to solid objects in Japan; they just have simple locks on the back wheel so no one can easily ride away on it).