In understanding frame size and bike fit, the first thing you must always keep in mind is that the size of the frame and fit of the bike must deal with the three basic contact points of the human body on the bike. These are the pedals, saddle, and handle bars. Nothing else matters.
The reason I say this is to destroy the first and one of the most common myths about frame size and bike fit. This myth has to do with looking for your hub in relation to your handlebars.
Since the head does not make contact with the bike (if yours does, you really got screwed), then the length of your neck, shape of your head, or position of your eyes in your head should in no way be a factor to determine frame size or bike fit.
If anyone sits you on a bike and tells you to look for the front hub or you are reading an article which tells you the same in a magazine, walk away from it right there because that person is telling you they know nothing about proper frame size or bike fit. I would not listen to another word they tell you.
regarding hubs in front of bar myth;
http://www.coachcarl.com/training_articles/bike_fit.htm