I was in a conversation with some professional runners. A hobbyist in the same club asked, "when does it stop hurting?" They laughed and said, "It never stops. It's about how much you can make the other guy hurt."

Cycling races are much the same with a team dynamic included. It's a matter of choosing between setting a pace that a sprint finisher can't follow over a long period, or sheltering a sprinter from the wind so he can put in maximal effort at the end of the race. There are all sorts of variations based on strength of team, weather, terrain, luck, politics between teams, race goals, etc...