Robert Axelrod opens his book 'The Evolution of Cooperation' with the question "Under what conditions will cooperation emerge in a world of egoists without central authority?" I cannot imagine a better description of a bike race!
He goes on to explain that under a particular set of circumstances one particular strategy of cooperation will emerge. He ran simple computer models of the game "prisoner's dilemma". To explain what I mean by this imagine you and friend are taken into police custody for stealing a car. You both have 2 options, either you blame the other or say nothing. If you both say nothing (cooperate) you both get a slap on the wrists and a fine. If you both blame the other one (defect) you both feel the full force of the law. But where things get interesting is when one of you cooperates and one defects. In this situation the one who cooperated gets the full force of the law and the defector walks free. This is all very well if you steal a car once, but it takes on a new dimension when you allow the prisoners to act and interact over and over. Axelrod set up a model whereby individuals were either cooperators, defectors or tit-for-tat (a strategy whereby their reaction on meeting an individual is a mirror of the other's reaction the last time they met).
Bear with me here - cycling comes up soon!
If everyone cooperates you have the utopian ideal and the population is perfectly stable and will remain that way forever. Alternately if everyone defects things quickly get out of hand, every meeting is negative for both participants and the whole thing collapses pretty quickly. But both these situations are pretty unrealistic and rely upon us picking a set strategy at the beginning and sticking with it indefinitely.You can imagine easily that if one of our saintly cooperators starts to defect, things work out very well for him and very badly for everyone else and again the population as a whole becomes unstable.
Axelrod then asked the question: what populations are stable to the inclusion of small numbers of defectors? It turns out that the simplest one you can think of is the one which wins out - a population of tit-for-tat who do unto others as others have done unto them.
So whats this all got to do with bike racing? Well...Imagine the situation. You find yourself riding in the singletrack and a rider who is clearly better than you in that section comes up behind you and asks to pass. The racing instinct says block for all your life, don't let this person past me. But consider the other course of action. You let them past without slowing down and then follow their line through the trail. You might learn a quicker way through and it is always easier to follow lines than make them. If you are really stronger than them, as soon as the trail widens you will go past and likely not see them again unless you are amazingly well matched. If you are well matched then working together will likely bring both of you back to the rider ahead. Consider a successful breakaway in the Tour -almost without fail the riders in such a break will cooperate until the last 5km. If they constantly attack each other, they become the unstable population of defectors we saw earlier and the bunch quickly brings them back.
The darker side of this argument goes as follows. As a racer you are not anonymous.Whilst I am thoroughly excited that the womens fields are growing every year, they are not so big that we don't all get to know each other (you only have to see us gossiping at the start!). So the old guard like me tend to cooperate. We know it all shakes out in the end. If you are new to racing you might assume we are a saintly population of always cooperate and that by defecting (blocking, sprinting away, generally being uncooperative) you will make swift and significant gains. But we are really tit-for-tat and you stand more to gain by joining us and working together than you do by kicking against us and making everyone lose.
Basically what I am saying is we can all play over-aggressive racing tactics such as incessant blocking of attempts at overtaking. But in the end it detracts from everyone's race and the strongest person will still win (and we'll all probably end up hating each other). So next time someone comes up behind you and goes to make a clean pass, be a cooperative racer, try and hold their wheel and show them when the trail goes your way.