The 51-year-old was three months into a 5000-kilometre cross-country cycling trip across the US, inspired by Martin Luther King jnr.

But much like her hero, she would never live to see her dream realised.

She had cycled alone, covering about 4000-kilometres and was less than 1000-kilometres from her final destination, the Martin Luther King jnr memorial in Washington.

Along the way, she made friends and was touched by the generosity of strangers who offered her a warm place to sleep or meal here and there.

But in the early hours of August 9, 2014 on a dark stretch of highway in eastern Indiana, her life was cut short when she was hit by a car driven by 25-year-old Clifford J. Henry.

Henry didn't stop.

At 3.38am, 911 received a call from a man who told the operator his son had hit what he thought was a dog, according to Wayne County Sheriff Jeff Cappa.

But when police got to the scene, what they had been told did not match up with what they found.

"Upon doing so, he located debris, which he felt was not consistent with what was reported," Sheriff Cappa told The Canberra Times.

"Further investigation by the officer led to him finding a bicycle, articles of clothing and the victim."

It was too late for Ms Abernethy and she died at the scene.

The case was investigated by the criminal investigation division at Wayne County Sheriff's Office and Henry was charged with leaving the scene of an accident resulting in death – a level five felony in the State of Indiana, which carries a prison sentence of between one and six years and a fine of up to $10,000.

A jury found Henry guilty and in June, he was jailed for seven years. Five years for the charges over the accident that claimed Ms Abernethy's life and two years for being on probation at the time.

For Ms Abernethy's family, her death has torn a hole in their hearts.

Her brother Mark is now planning on completing her bike ride later this year with friends and family, starting at the crash site and ending at the memorial on what would have been Ms Abernethy's 54th birthday.

Mr Abernethy said their mother Winnie had desperately wanted to complete his sister's journey after she was killed, but tragically she died just three months later, her wish unfulfilled.

"My mother was determined to get to the States to honour Joanna's spirit and life and to actually finish her ride," he said.

"It's really a healing thing, completing something I know my mother really wanted to do ... but it's a way for me to feel like I'm doing something for both my mother and sister now."

Mr Abernethy believed his sister would have felt honoured by her friends and family completing the ride in her memory.

"The fact that we're respecting her courageous, generous spirit and doing something that she felt really strongly about, I think she would feel really good about that," he said.

Mr Abernethy said it had been difficult being half way across the world as the man responsible for his sister's death was brought to justice.

"It's been a long time," he said.

"There was an anxiety that perhaps he would be acquitted and that would have been an awful outcome and it would have been very hard to start this ride knowing that that person was still out there."

Mr Abernethy said he thought justice had been done, but felt no sentence would have been enough for the loss his family has endured.

He wanted his sister remembered for her altruism. She had used her bike ride to fund raise for several charities.

"She was an issues person – she was concerned about the environment, equality around the world, causes, people who fought for justice," he said.

"She was big hearted."