Well that depends, if you breathe city air and Diesel fumes everyday it may not be great for you.
If you are dressed in black lycra on a black bike with a black helmet and no lights (yes I saw him….just) at dusk then you may find yourself kissing a truck or something similar that didn’t see you. Not good for your health!
These kinds of things aside, an article I found on the BBC “Fit legs equals fit brain” sounds good to me, have a read for yourself and see what you think.
I think cycling is good for me.