OK, I understand the whole rotating weight concept with bicycle wheels. If you have tires that are, lets say, 10g heavier than a previous set of tires, that rotating weight will feel like 100g or so (just an example). In essence, bicycle wheels is where you would really like to save weight.
But what about dead weight? Lets say I have a steel frame that is 2 pounds heavier than an aluminum frame. Is there a difference in performance, besides the fact that you're just carrying around 2 extra pounds?