What's a Prologue in Cycling
A prologue is an individual time trial at the beginning of the stage race that must not exceed 8 kilometers (5 miles). It's not regarded as a stage, but the rider's times still count towards general classification (GC). It's primarily used to determine who wears the leader's jersey on the first stage.
They're generally used on stage races longer than four days, and are much more common in UCI level stage races than Pro/1/2 level races. Generally, all the grand tours: the Giro d'Italia, Tour de France, and La Vuelta will have them, along with other popular UCI stage races such as the Tour de Romandie.
Pro Cycling Bets
Since Prologues are so common in the prestiguous stage races, they truly separate who can perform well in these races. True GC riders will be able to perform well both on climbs and in time trials, compared to only hill climbers (say a Simon Geschke).
It's also worth noting that younger riders seemingly are more willing to realize the benefits of aerodynamics and their drag co-efficient (CdA) in recent years and as such have generally been performing better in these prologue time trials than older riders.
Certain riders pure time trial riders also perform exceedingly well at Prologue's and then go on to support their team in the later days of the stage race. Which is worth taking into account when placing bets.
Fabian Cancellara won seven prologues in the course of his career (and he was most certainly more than a TT rider), and these days Filippo Ganna springs to mind as another excellent Prologuer.
