American Kristin Armstrong repeated as Olympic time trial gold medallist at the London 2012 Olympic Games. Armstrong led the event at every split, opening her advantage with each kilometre on the 29km course. Her final time was 37 minutes, 34.82 seconds.
"Today I didn't know until I crossed the finish line," said Armstrong. "People try to tell you you are on track, but out on the course today, the information I was getting was that it was a close race. I just needed to give it everything if I really wanted it."
Judith Arndt of Germany claimed the silver medal, 15.47 seconds back from first.
"I'm absolutely happy today," said Arndt. "It always depends completely on your physical condition. TOday was a good day for me."
Russian Olga Zabelinskaya finished with a bronze medal, adding to her bronze medal from the road race.
"Two medals, of course, were something that I was dreaming about," said Zabelinskaya. "It was a dream and I did not expect it."
Armstrong took time away from cycling to start a family and returned over the last two years to defend her Olympic title.
"When she stopped, she was on top. You don't lose what you've got," said Armstrong's teammate Amber Neben, who finished seventh. "You don't lose the fact that you're a great bike racer."
Clara Hughes finished fifth. The 39-year-old crossed the line in a time of 38:28.96. She was third fastest at the first split, but dropped back during the middle portion of the course.
"I didn't think it was good enough when I crossed," said Hughes. "My whole goal here was to be better than I ever have been and I honestly was it's just that there were four people better than me."
"This was the best preparation I've had I gave everything I had and I was fifth best in the world today."
Just as the media scrum was wrapping up, Hughes let go of a little secret.
"I had a really bad accident in May and actually broke my back and had a fractured vertebrae from that accident in Gatineau that I had to push through a lot of pain for about five or six weeks, I've never experience that kind of pain," said Hughes. "I never gave up on myself and I just thought I'm just lucky that I can pedal my bike, and I get to live this experience and that's what I've always tried to show young people, is that don't ever give up on yourself."
Canadian Denise Ramsden finished 19th.