CALLIE Le Roux and Stewart Boswerger are careful to point out that they are not your everyday cyclists.
And that becomes abundantly clear when you realise the scale of the fundraising mission they are about to embark on.
Saddled up on a pair of unusual-looking, fat-tyred bicycles, the pair will ride 500km across the Simpson Desert over what promises to be 10 extremely challenging days.
The Desert Man Can fundraiser will kick off on August 14, with Callie, Stewart and support truck driver Dexter Lazarides driving across western Queensland, into Alice Springs and then finally to their trek's starting point at Purni Bore, in the far north-east corner of SA.
Stewart said the ride would cross the Simpson via the French Line, finishing in Birdsville, and taking in the desert's world-famous sand dunes, including the fabled "Big Red".
"Big Red will certainly be a bit of a challenge," he said.
"In fact I think there will be a few dunes along the way where we'll just have to push the bikes along.
"We are hoping that early on in the journey we'll be able to average 60-70km a day and then taper it back once we get towards the eastern side of the desert where the bigger dunes are.
"It's going to be really hard work for us because we are just normal blokes. We are not proper cyclists."
It's all for a good cause, with the challenge raising money for Beyond Blue.
Stewart gets up at 2.30am some days to complete 80km training rides and wants to start beach riding soon.
Callie's preparation has been hampered by a broken foot, though he is determined to continue the challenge.
One of the support trucks driven by Ipswich business owner Mr Lazarides will carry supplies and ensure that the riders are safe from other speeding vehicles, but Callie and Stewart will still sleep under the stars in swags during the trek.
To donate to the cause, visit give.everydayhero.com /au/desert-man-can-2017 or www.expeditionmission.com/ desert-man-can-2017/.