I don't know about you, but someone smoking and bicycling at the same time has to be the [B]dumbest thing I've ever seen.
First of all, there have been various times in my life when I've seen other cyclists ride by with lit cigarette either in mouth or in hand. Somehow this doesn't belong at least while riding the bicycle? It looks stupid.
Second, let's think about the medical aspects. Bicycling is a sport which does help keep a person healthy. It may even keep the ill effects of smoking at bay for a while, making the person think s/he is invincible. But sooner or later, the illl effects do catch up with the bicyclist who smokes, especially while riding.
Third, doctors won't recommend that their patients smoke these days.
Lastly, I have never taken up smoking and never will.