Smith received multiple injuries and was still being assessed at Dunedin Hospital last night. His crew reported he was in a stable condition.
The Auckland-based motocross rider was in Alexandra to stage the first South Island Big Air Boot Camp. He had been teaching riders on a special motocross track complete with free-riding jumps and freestyle ramps, on farmland near Alexandra.
Three years ago he crashed during training, receiving a severe brain injury. He spent eight days in an induced coma and five months in hospital, learning to walk again.
Smith told the Otago Daily Times at the boot camp on Saturday morning, he had just successfully performed a back flip manoeuvre - where riders flip their bikes backwards while jumping from a ramp.
"That's my first back flip since I was injured, but you can't be the tutor at something like this and tell others how to do it, if you don't step up yourself.
"Landing these things is probably 50:50 whether you make it, or whether you have a trip to hospital, but I'm used to hospital - it's my home away from home."
A group of spectators and riders at yesterday's boot camp watched in awe as Smith successfully completed another back flip and then in horror as he misjudged the manoeuvre and crashed during his next attempt just before noon, falling away from his bike and landing on his shoulder.
The South Island manager of Smith's Moto Mayhem company, Regan Healey, of Alexandra, said the rider's new helmet "probably saved his life".
"He'd nailed the back flip the day before and again the first time [yesterday] and then had another go, doing it for the boys who were there, to give them a buzz, but he under-rotated, and crashed."
He estimated Smith fell from a height of about 9m.
Ironically, the first back flip, on Saturday, was believed to be a New Zealand first - the first time anyone had completed the trick on a 450cc bike on dirt, Mr Healey said.
Smith's injuries included a dislocated shoulder and broken collarbone and checks were being done to determine if he had suffered any spinal injuries. He was taken to Dunstan Hospital first and transferred to Dunedin Hospital.
"He wasn't looking too flash, but he's a real fighter; he proved that last time around," Mr Healey said.
Last night, Mr Healey was fielding calls from members of the Crusty Demons and motocross riders around the country, wanting to know how Smith was.
Smith set up Moto Mayhem, a custom motocross graphics business, after "losing my dream job and giving up the Crusty Demons" after his earlier crash.
He remained an "adrenaline junkie", he told the Otago Daily Times on Saturday, and loved showing others how to perform tricks.
"And look at me, three years after that accident - I'm back doing back flips and nothing can stop me. I'm doing what I love."
