Shoulder the bike on long, death march type run-ups. I did a race this weekend and it seemed like most people were rolling their bikes up a long hill. I did it that way myself for a lap or two, but when I actually decided to pick it up, I found that the difference in effort was significant. When the bike is on your shoulder, the rolling resistance is zero. When it's beside you, chances are you will lean on it and it will be slowing you down. That also creates more chances for stumbling.