They collided, sending her flying over the handlebars and smashing into the pavement, cracking her helmet, according to the Wall Street Journal.
Emergency surgery removed part of her skull; she fractured her pelvis and spine and sustained permanent hearing damage. If not for doctors at New York-Presbyterian Hospital, she said, "I wouldn't have survived."

Off-Leash Consequence, Sara D. Roosevelt Park - March 10, 2011. Humans aren't the only ones at risk. An off-leash dog was tragically killed after running into traffic and being struck by a vehicle. The beloved dog and owner had been in the lower Eastside park when tragedy struck. (Photo: © NYC Park Advocates)
In 2006 the Juniper Park Civic Association in Queens sued the Parks Department over its "courtesy" off-leash hours and its lack of enforcement of existing leash laws. The City in turn amended its health code and made off-leash hours official.
While serious accidents with dogs are rare, cyclists said, a handful occur every year on Central Park's increasingly crowded roadway, the 6.1-mile loop around the edge of the park that's a jumble of bikers, roller skaters, runners, dog walkers and even cars. It is legal to have dogs off their leashes there during designated hours, including between 5 a.m. and 9 a.m., when cyclists and runners swarm—a policy officials are now starting to question.
"I think a lot of these owners are really, really foolish for letting their dogs run across the road or even letting them near the road," said Linda Wintner, who was hit by an unleashed pit bull while riding her bike through Central Park in April 2010 and suffered a mild concussion. "A dog's an animal. It might not listen."
Although a brochure on the Central Park Conservancy website urges people to keep their dogs "on a short leash" when crossing the drives, the admonition is intended "to be helpful and advisory, but not necessarily regulatory," said Dena Libner, a spokeswoman for the conservancy. "We try to avoid language that's 'no, no, no,' but in instances like this, when clarity is called into question, it's worth revisiting."
City officials, the Central Park Conservancy and dog advocacy groups agree that changes might be warranted. "I'm not sure why we did not include the park drive" in the list of prohibited places for dogs to be off-leash, said Michael Dockett, assistant commissioner for urban parks services. "We would probably take that under advisement and consider it."

A Common Sight In Prospect Park. A woman plays with her off - leash dog last week in the afternoon. The public often complains about lax enforcement of off-leash laws. A number of Parks Department employees, as well as members of the public have been attacked this year by off-leashed dogs. (Photo: © NYC Park Advocates) Click on image to enlarge.
By contrast, Prospect Park forbids dogs to be off-leash everywhere, including roadways, with the exception of three designated areas during the city's off-leash hours: Long Meadow, Nethermead and the Peninsula.
That "could be a really smart way of doing it," Ms. Libner said.
It would also clear up the current confusion among cyclists, dog owners and advocacy groups, some of whom insisted it was illegal already.
"Dogs are not allowed off-leash ever on the roadways simply because it's just too dangerous," said Bob Marino, president of the New York Council of Dog Owner Groups.
When told that the Department of Parks and Recreation and the Central Park Conservancy agreed that it was technically allowed, Mr. Marino said that he would favor a discussion about changing the regulation.
Regardless of the law, "it's absolutely ludicrous behavior for a dog owner to have their dog off the leash on a roadway," he said.
Still, on a recent morning in Central Park just before 9 a.m. a handful of dogs, large and small, trotted along the road with no leashes.
Lizzy Klein said she moved to the Upper East Side to take advantage of Central Park's off-leash laws with Mimosa, who is half German Shepherd and half Husky. "There's not really many other ways in New York to get a big dog like this to get the exercise," she said, adding that she normally took Mimosa to the North Meadow and that she was well-trained.
When told there had been a series of accidents involving cyclists and dogs on roadways, Ms. Klein frowned.
"That's a bummer," she said. "I think it probably depends on different dogs. I mean, she's 8 years old, so the only thing that gets her to do something erratic is a squirrel."
That is exactly what caused a dog to bolt across the road in 2009 into the path of Theresa van Vugt, who was leading a bike ride into the park. As Ms. van Vugt, a triathlon coach, turned toward Tavern on the Green, she heard someone "screaming, 'No, no, no!'" she said.
Then she spotted a squirrel scurrying across the road, and a golden retriever in pursuit.
In the collision, Ms. van Vugt said she fractured her elbow, wrist, hand and three ribs. Her knee later required surgery and she suffers from permanent nerve damage, she said. "I've never had that many parts of my body hurt all at once all at the same time," she said.
She has since witnessed several other crashes, she added, and heard about others from friends who compete, coach and train in the park. "It's probably something we hear about on a monthly basis," said Ms. van Vugt. Not every owner even stops, she said, and one dog owner cursed at her when he overheard her warning other cyclists about off-leash dogs.
Use of roadways has become an increasingly contentious issue in the city's parks, as the number of users rises.
Although Prospect Park has largely avoided dog-and-cyclist collisions, an accident this summer involving a cyclist and a pedestrian that left a woman with serious brain injuries prompted park officials to convene a working group in September to address safer ways to share the roadway.
Last week, officials instituted a pilot program to increase safety on the roads, including narrowing the vehicle/cycling traffic to one lane and posting more signs warning cyclists to be aware of pedestrians.
The park is "trying to strike a balance that leaves everybody feeling safe and comfortable and accommodates all these different needs," said Prospect Park spokesman Paul Nelson, who said that there have been four accidents involving cyclists and pedestrians since June.
Ms. Chilton, 51 years old, was cleared by her doctors to ride again last month. But though she was an avid cyclist for 20 years, she said she has no plans to mount a bike again any time soon.
"I would never ride in Central Park," she said. Seeing the off-leash dogs "just makes me too nervous. I just couldn't do it."
Last month, Ms. Chilton filed a lawsuit against New York City, the Central Park Conservancy and the city's Department of Parks and Recreation, claiming that they failed to create and publicize safe off-leash laws. The city Law Department declined comment.
She said she hopes that officials clarify the rules—and enforce them.
"I would ask that they go out there at 7 in the morning and see all the people that could come to harm if there are no rules," she said. Posting signs around the roads "seems like something that would be pretty easy to do to make it safer."