Emma Pooley was inconsolable after finishing sixth in the London 2012 women's Olympic cycling time-trial at Hampton Court.
The 29-year-old from London, world champion in 2010 and silver medallist in Beijing, finished the 29-kilometre route in 38 minutes 37 seconds as Kristin Armstrong of the United States defended her title.
A tearful Pooley said: "I'm just a bit disappointed. I shouldn't have got my hopes up."
Armstrong is a 38-year-old mother and won through a dominant display, beating world champion Judith Arndt of Germany by 15 seconds. Asked if she took inspiration from Armstrong's performance, with the 2016 Games in Rio de Janeiro in mind, Pooley said: "To have babies or something?
"I'm not really thinking about four years ahead at the moment. I don't know anything about the Rio Olympics. Kristin Armstrong is an absolutely fantastic rider, so I'm not hugely surprised that she's won. I've actually never beaten her in a time-trial."
Armstrong was last of the 24 riders to roll down the start ramp and led at every time check, finishing in 37mins 34secs, with Arndt second in 37:50 and Russia's Olga Zabelinskaya, who finished third in Sunday's road race, taking bronze in 37:57.
Lizzie Armitstead, Britain's first medallist of London 2012 after winning silver in Sunday's road race, clocked 39:26 to place 10th.
Since winning silver on a hilly course in China, Pooley's focus has been on the time-trial, but the flat nature of the route favoured a more powerful rider than the petite Briton.
For a short time Pooley was in a medal position, but she was diverted from the thrones positioned in front of Hampton Court Palace - a waiting spot for the provisional medallists - as she was swiftly deposed from the podium. After missing out on improving on her Beijing performance, the result was irrelevant to Pooley.
She added: "I'm not sure who won, but whoever's quickest wins. I can't whinge about the course, it was the same for everyone. I don't know where I came, I just know that I didn't win. It's more disappointing when you think you might have a chance of getting a medal. When you don't... it's the mistake of being an optimist, I should've been more pessimistic."