The 25-year-old powerhouse and her Dutch teammates attacked all day long in Sunday's rain-sodden women's road race. When a breakaway finally came to fruition about 40 kilometres from home, Vos was in it.
After American Shelley Olds had a puncture, it came down to Vos, Russia's Olga Zabelinskaya and Britain's Lizzie Armistead. Knowing they each had a medal if they kept the peloton at bay, the trio worked together until it was time to decide what colour the medals would be.
With 200 metres left on the straightaway from Buckingham Palace, Vos accelerated past Zabelinskaya with Armistead on her back wheel. But Armistead could not peg Vos back and had to settle for silver ahead of Zabelinskaya.
"For me, the plan was to attack quite early and many times," Vos said.
Joelle Numainville of Laval, Que., finished 12th despite losing control trying to avoid another fallen rider with 10 kilometres remaining.
Yellowknife's Denise Ramsden was 27th and veteran Clara Hughes, a native of Winnipeg who calls Glen Sutton, Que., home, was 32nd after spending much of the race near or at the front of the peloton.
Vos came into the race with world championships in road cycling, cyclo-cross and track on her CV, as well as an Olympic gold medal in the points race in track cycling at the 2008 Games.
"She is a machine right now and the rest of us are not yet at this high level," Zabelinskaya said.
Armistead's medal was the first of the Games for the host nation and helped make up for Saturday's disappointment when the star-studded British men finished down in the standings.
Asked if she lost the gold or won the silver, Armistead said she saw it as a win.
"I'm just so happy I committed to the breakaway," she said. "I was there with Marianne Vos and if you know much about women's cycling, you know that she's the best rider in the world on most kinds of courses.
"My only regret is maybe that I didn't try and jump her earlier in the sprint but she generally is faster than most of the girls on the circuit so I'm pretty chuffed with silver."
The riders came out for the pre-race introductions to sunshine and drops of rain. A half-hour before the noon start local time, the clouds turned dark and there was thunder. Ten minutes later, it was raining.
The rain stopped just minutes before the start, prompting racers to hurl their balled-up rain jackets to the side. Still they had to contend with a greasy surface or, in some cases, pools of water.
The skies opened again in the final run to the line, only for the sun to return minutes after the finish.
Zabelinskaya shrugged off the difficult conditions.
"It's not the first race for everyone in the rain," she said. "We're used to it."
Armistead welcomed the lousy weather, saying she hates the heat.
"I've been praying for rain," she said. "Particularly when we were in the breakaway and there was a real downpour. I thought 'Great,' because the break has more chance of working in those conditions."
The entertaining Brit — she became a vegetarian at 10 because she didn't like meat and "I can't sort of get my head around eating a corpse" — did lament losing her "lucky" sunglasses during the race when she had to take them off because of the rain.
A British reporter later asked her if she wanted the glasses back.
"That would be nice. But it would be nice if Oakley gave me a few more sets maybe," she said with a laugh.
Like the men's race, there were no team radios so riders had to rely on numbers on a team official with a whiteboard to convey information. Armistead said that proved to be difficult since the official's pen wasn't working in the rain.
The 140-kilometre women's race was a condensed version of the men's 250-kilometre trek, with 66 women from 35 countries competing before a bumper crowd. The field featured all three medallists and five of the top-six finishers from the 2008 event in Beijing.
The women started on The Mall, passing by Buckingham Palace and other tourist attractions before crossing Putney Bridge and heading out of the city for suburban Surrey and two laps around Box Hill.
Then it was straight back to the city and a finish down a stretch of The Mall.
Despite the best attempts of the Dutch, the peloton stubbornly resisted breakaway attempts until Zabelinskaya finally made one stick near the summit of the second trip round Box Hill.
"For me it was the moment for attack," Zabelinskaya said.
With some 35 kilometres left, the foursome had a 23-second lead as they headed back to London in torrential rain.
Olds's bike then betrayed her, leaving three up front with 28 kilometres left.
Italy, Germany and others looked to push the peloton pace but the three frontrunners increased their lead as they crossed over the bridge into London.
Armistead said she learned from the men's race.
"We saw that once a committed group goes, it's hard to chase from behind," said the 23-year-old whose silver-medal performance continues the passing of the British road racing torch from 2008 Olympic champion Nicole Cook, who finished 31st.
It was a race that saw everything from sunshine to torrential downpours, crashes on wet, greasy pavement, plenty of punctures and a string of breakaway attacks.
At least three helicopters were hovering high above as the women set off, followed by a caravan of cars, vans, ambulances and motorcycles.
Several women were slowed by early punctures as Janildes Fernandes Silva, one of two sisters on the Brazil team, launched an early solo break. It didn't last long, but it earned her some face time on camera.
The rain returned after some 40 minutes as the changeable weather conditions continued.
An hour into the race, Hughes was at the front of the peloton when Dutch rider Ellen van Dijk launched a pair of unsuccessful breaks.
More punctures followed as riders had to negotiate pools of water on the road. Two-time world road champion Giorgia Bronzini of Italy found herself changing a tire as American Kristin Armstrong launched a break 75 minutes into the race.
Soon after, a bottleneck on a narrow stretch of road sent a Brazilian into a ditch and crashed several others at the back of the peloton.
The Dutch attacked again and again, usually led by van Dijk. Hughes remained in contact at the front of the bunch and the peloton pegged back all of the breakaway attempts in the first two hours.
Hughes led the way as they started the Box Hill climb for the first time, negotiating the narrow road lined with a dense wall of flag-waving fans.
Vos then attacked, stringing out the riders with 57 kilometres to go. Hughes remained in contact, moving back up the field when the peloton regrouped.
All three Canadians were near the front as the riders approached the Box Hill climb for a second time.
A nasty crash saw a rider go straight over Armstrong, the defending Olympic time trial champion, when she went down on a tight corner.
Then came the key break.
When push came to shove, Zabelinskaya said she knew she did not have the sprinting chops to beat Vos or Armistead.
"We worked together until the finish," said the Russian. "I knew they would beat me in the sprint."
Armistead saw it a little differently.
"Olga didn't do as much work as I would have liked," she said. "But she got the bronze, so it's all right."
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