Jonathan and Benjamin Siero are used to doing things as a team.
The 32-year-old twins from Perth were born just 12 minutes apart and have fond childhood memories of being driven across the Nullarbor to visit relatives during the school holidays.
Now, as adults, they're doing it on bikes.
Their stepfather Sam was last year diagnosed with brain cancer and given just 12 months to live, so they chose to make the trip to raise funds for medical research.
"The diagnosis came as a shock to the family, so we decided to raise money for [charity] Brain Cancer Collective," Jonathan said.
"This seemed like an incredible challenge to do and something we wanted to do for a while, so that's why we're cycling to Melbourne."
The twins have so far raised $10,000 online.
Benjamin said their sick stepfather Sam was quietly impressed.
"He's got the façade of a grumpy old guy, so if he does show any sort of warmth then you know it means something," he said.
The 3,000 kilometre journey kicked off on Monday and will take 34 days to complete.
The brothers have been through months of training to get to this point.
"I started running more and more everyday to build up my fitness, then switched to the bike and was doing 40 kilometres every weekday to prepare," Benjamin said.
The brothers' biological father, Gerard Siero, is driving as an escort for his sons.
He's carrying a months-worth of supplies in a Volvo sedan and watching out for trucks, all while communicating via a radio.
"We're planning to stop in Bruce Rock, Moondie Rocks, just past Kalgoorlie, Widgiemooltha, somewhere about halfway through Norseman and Fraser Range and then Balladonia … the list goes on," he said.
Their initial goal was to raise $5,000 but it's now hoped they'll reach $20,000 before the end of the journey.
Jonathan said anyone living along the Nullarbor was welcome to shout the trio a drink.
"We won't say no, I'll definitely have a beer," he said.
"Maybe a cup of tea for Ben."
More information on their journey can be found here.
