The Team Sky rider made it into the decisive break on the penultimate lap and was joined by compatriot Adam Yates and several other riders. Yates was dropped on the final climb but Thomas crashed on the last descent. He remounted and finished the race in 11th place, 2:29 minutes down on winner and Olympic gold medallist Greg Van Avermaet (Belgium). Jakob Fuglsang (Denmark) and Rafal Majka (Poland) rounded out the podium.
Pre-race favourite Chris Froome finished in twelfth place. The Tour de France winner was marked by several favourites and was unable to go on the attack when Vincenzo Nibali and Fabio Aru (Italy) led a group up to Thomas' break before the final ascent.
Froome did attack on the final climb but was already a minute down on the leaders. Yates crossed the line in 15th. Steve Cummings and Ian Stannard, who both worked for the team in the first half of the race, abandoned before the final 60 kilometres of racing.
Chris Boardman, who won an Olympic gold medal in the individual pursuit in Barcelona in 1992, and took bronze in Altanta in the time trial four years later told the BBC that Great Britain rode a tactically smart race but just did not have the legs in the pointy end of the race.
"We did not win a medal because ultimately we did not have the legs for it but, tactically, that was the best Olympic road race I have seen from the British team, so hats off to them,” he told BBC.
“Thomas did a phenomenal job, the whole team did. Britain's best rider was expected to be Froome but for me Thomas would have been the better sprinter if it had come to that."