The 27-year-old finished 20 seconds behind winner Anna van der Breggen (Netherlands) and the three trailing riders after chasing on having lost ground on the steep climb to Vista Chinesa with around 24km to go.
After a less than ideal build-up week to the Games, which saw the news break of Armitstead's missed anti-doping tests, the world champion says she couldn't have done any more to stay in touch with the riders that went up the road ahead of her on the climb.
"I stuck to my tactic. I needed to limit my losses on the climb and that’s exactly what I did." Armitstead said.
"I couldn’t have climbed any faster. I’m happy with the tactic I had, I just simply wasn’t good enough at climbing, so I can be proud of the effort I did.”
While the profile suggested the final climb would be the most decisive factor in the race, like the men's race on Saturday the treacherous descent back to Copacabana played as much of a part.
Annemiek van Vleuten (Netherlands), who was out front solo on the descent and looked in with a good chance of winning, took a horrific spill on a corner and Armitstead said she wasn't prepared to take "extraordinary risks" on the way down.
“It was particularly difficult," Armitstead said, "but I went into this thinking I’m not going to take extraordinary risks. I wanted to get down safely at a speed I was comfortable with.”
“I would’ve put some money on Anna (van der Breggen) to win this race. She’s a phenomenal athlete and this course was designed for her. I’m really, really impressed.”
Despite riding the race under the cloud of last week's news of her Whereabouts Failures, Armitstead said she felt it was right for her to be at the race and was happy to add another Olympic appearance after her ride to a silver medal at London 2012.
“Yes, of course [I should be here]. I feel good. It was a victory to be here for me. It’s been a very difficult couple of weeks, but I’m happy I was here to represent my country, definitely."
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