His sister Samantha Venis said her brother, who is one of four siblings, moved to Melbourne only five months ago and was working as a diesel mechanic. He is originally from Amberley in Canterbury.
Demmocks suffered multiple skull fractures and brain bleeds, as well as fracturing his neck and T5 vertebrae, and is being treated at Melbourne Hospital.
He is in an induced coma because of the severity of the injuries and the family were unsure of the extent of the damage to his brain at this stage, Venis said.
"We don't know what he's going to be like when he does wake up.
"We haven't had any updates. It's going to be a long process before there is anything significant."
A Give a Little page has been set up to pay for travel costs for his family, who are at his bedside, and to pay for the costs of airlifting Demmocks from the crash site to hospital.
To donate visit Help Brendon and his Family.
