This was the 18th appearance of the event, previously held in 1896 and then at every Summer Olympics since 1936. It replaced the individual time trial event that had been held from 1912 to 1932; the time trial had been re-introduced in 1996 alongside the road race.
Pollution issues Prior to the opening of the Games, the
International Olympic Committee was keen to play down the risk that athletes faced from pollution; however, the organizing body considered rescheduling of endurance events (such as the cycling road race) if the pollution levels were too high. Athletes partaking in these events can consume 20 times the amount of oxygen as a sedentary person. A higher level of pollution in the air could adversely affect performance, damage or irritate an athlete's lungs, or exacerbate respiratory conditions, such as
asthma. Independent sources showed that pollution levels were above the limit deemed safe by the
World Health Organization on August 9. However, the cycling event went ahead as scheduled with no objections from the athletes. Fifty-three of the 143 cyclists pulled out during the race; however, this is not unusual (over half withdrew mid-race at the 2004 Summer Olympics). Post-race, a number of riders highlighted the punishing conditions, in particular the
heat () and
humidity (90%), which were much higher than in Europe, where the majority of UCI ProTour races are held. Pollution, however, was not widely cited as a problem, though
Stefan Schumacher of Germany, who had been considered an outside favorite for victory in the event, said the elements and the pollution played a role in his withdrawal.
Pre-race favorites Among the pre-race favorites was the entire Spanish contingent of riders. It included two winners of
Grand Tours in
Alberto Contador and
Carlos Sastre, along with highly regarded countrymen
Alejandro Valverde, winner of the
2008 Critérium du Dauphiné Libéré and the reigning
Spanish national road race champion, and
Samuel Sánchez, who had won three stages in the
2007 Vuelta a España. They also had 2008 Tour de France
points classification winner and three-time
world champion Óscar Freire available to
work on their behalf. Valverde was seen as the strongest threat among the Spaniards. Other medal hopefuls included the defending Olympic champion
Paolo Bettini of Italy, Germany's
Stefan Schumacher, and Australian
Cadel Evans, twice a runner-up in the
Tour de France (2007 and 2008). It was thought that members of the overall strong squads from Germany and Luxembourg could also contend for victory. The German team contained Schumacher and many veterans of Grand Tours such as
Jens Voigt to work in support, while Luxembourg had the Schleck brothers
Andy and
Fränk, along with
Kim Kirchen, all of whom had worn leader's
jerseys during the 2008 Tour de France. ==Course==