WHEN his mates were angling for first cars and taking licence tests, Sam Mitchell was lost in his own world of “weird bikes” and solar-powered technology.

A committed environmentalist, the Orbost teen had little interest in transport reliant on fossil fuels.

“As I was gaining my independence, I wanted to build a bike that ran on solar energy, as that is so much more satisfying,” says the 19-year-old engineering student.

“You get to build something and step back and say, ‘Look, it works, I built that.’

“Growing up, I was always that kid building the weird bikes.”

His teenage years have been marked by trips to the tip, and hours spent experimenting with his bikes. He does a quick count and reckons he has built “more than 10 bikes, but fewer than 50, it’s hard to say”.

Not all have been solar-powered, and not all have been spectacular successes. He’s built double and triple seaters, and Asian rickshaws. There was the memorable “couch bike”, which was built to transport friends and family around the town, with the bike attached at the back.

“It was basically a couch with a wheel on either side of it and I would pedal people around at the back,” says Sam, whose mum runs her own cycling tour business.

“It seated up to four but not for very long. We took it down to look at the New Year’s Eve fireworks one year, but on the way back the steering arm broke.

“It had more to do with the construction of the steering arm than the weight of the people. Although that many people is a lot to ask of a couch bike.”

It came as no surprise when Sam graduated from high school and he announced he would be setting himself a challenge to ride one of his solar-powered bikes (he has four) around Australia.

In March last year, he set off on his recumbent bike, named Mark IV Solar, a 4m long beast that is much larger than standard bikes.

It was his fourth design, having tried chain drive, hub drives, front-wheel drive, rear-wheel drive and various combinations.

Atop the bike’s A-frame is a solar panel sheet that charges the battery and keeps the pedals turning when Sam is tired.

It took him nine months to pedal from Victoria up the east coast, across the Northern Territory, down the coast of Western Australia and back across the Nullarbor. At his fastest Sam was going 70km/h, and on a good day would notch 200km.

“Amazingly, it didn’t break down to a catastrophic degree, nothing that I couldn’t fix,” he says.

The trip also changed him in subtle, unexpected ways.

“I look at how I was before I went on the trip and I cannot believe the difference,” he says.

“I think I was quite immature and there were certain things I took for granted that I don’t any more. ”

Sam says he has nothing concrete planned for the future, but has some vague ideas.

“I would love to go around Australia across the dirt, or Cape York, or maybe Antarctica, or it would be great to take the bike overseas ...”