One of the worst rookie mistakes that I have seen occur when people try something new at a race. The golden rule of bike racing should be never try anything new at a race be it equipment, tatics, a pre race food, or anything at all. People always say train as you race. Which is true you should always train for the specific events that you compete in, but lots of people forget the other half, race as you train. You should never do something in a race that you haven't tried in training.
-Matt-