It is usually a good idea to eat something for breakfast, even if you don't ride immediately thereafter. Sometimes, if my time is limited, that is a piece of toast but then I know I will need to take something to eat on my bike ride afterwards, i.e. powerbars of some sort, gel, fig newtons, bananas, something like that.

What I find is that if I eat a little protein in the morning I have more energy and more sustained energy on the bike, i.e. a piece of toast or english muffin with peanut butter on it, with a piece of fruit and orange juice; or an english muffin with a cooked egg, fruit and orange juice. This works for me, but everyone is different. Some people have a hard time eating before riding and have to give their stomach time to digest, others can just go out and ride after eating a bunch. The training advice usually is that you shouldn't probably try to eat too much since then all the body's energy is going to your stomach to try to digest rather than to your body (Don't know if this is true or not).