She wasn't wearing a helmet as she shot into the path of a car on the 100km/h road and was thrown from her bike.
"I can remember flying. That's all." And before that, "I can sort of remember when I was swimming with my friends."
Since being woken from her coma last Thursday, Samantha has been speaking, is able to walk and is showing few lasting effects.
She has a collection of scars and bandages on her legs, arms and head, but remarkably, she suffered no broken bones.
Starship hospital neurosurgeon Andrew Law said Samantha was fortunate to have pulled through as she had.
"She's a very, very lucky young lady ... just exceptionally lucky. We see kids with similar things, or less, who don't survive. Tomorrow we may have someone with a similar accident who doesn't wake up," he said.
Samantha had suffered some minor brain damage in the collision, which caused bruising in her right temporal lobe.
"She's done remarkably well," Dr Law said. "She had a severe head injury - her whole brain got shaken around."
Doctors had to reduce swelling and release pressure on her brain, as well as drain spinal fluid, Dr Law said.
She also had serious wounds to both her legs, her shoulder and an elbow.
The biggest test in her recovery occurred last week, the neurosurgeon said.
"That's the real test, being off the machines. You have to wake up and talk and move. She's going to take a year to get back to herself."
But parents John Robertson and Sherry Coulson, who are separated, said their daughter was well on the way to getting back to her old self.
"It's a bloody miracle. It's absolutely unbelievable," Mr Robertson said. "She's walking and she's talking, which is the main thing. She's talking like she never even had a head injury."
Ms Coulson doesn't think it'll be too long before her little girl is home. "She really just wants to get home and hug her little dog and see her rabbits. It's all positive from here."
