If Lance was 1st last year and wears number 1, why is Beloki wearing number 21 since he was 3rd last year?
The only rider number that indicates the placing of a rider from the previous year’s race is the overall winner. So in the case of this year’s Tour de France, it is Lance Armstrong that wears number 1. There is no particular order for the riders from other teams. This rule applies to the three Grand Tours, the World Cup and generally all other major races on the UCI calendar.