VALENCIA: Australian cycling star Stuart O'Grady was cleared to leave hospital later on Wednesday after his collapse in the wake of a 'hot lap' of the Valencia MotoGP circuit on Sunday according to Cycling Australia.

The 2004 Madison track cycling Olympic champion collapsed and suffered a seizure soon after the high speed thrill ride and believes it was probably triggered by the stress on his body from the extreme experience.

However, doctors have given the 36-year-old 2007 Paris-Roubaix winner the all clear after a series of medical tests including an MRI scan.

"When the ride finished of course I could feel my heart rate soaring, my blood pressure rising, but I didn't give it much more thought," said O'Grady, who has also won two stages of the Tour de France.

"But then I started having blotchy vision and 20 minutes later I had a seizure and collapsed.

"It was possibly the extreme 'hyper tension' or maybe an old scar on my brain from one of my previous crashes but there's no use speculating or guessing, it's happened and that's that."

O'Grady, who owns three other Olympic medals all on the track, said that he had, nevertheless, experienced a real thrill being on the Ducati bike which was piloted by American motorcycling legend Rany Mamola.

"The ride around the Valencia circuit was unbelievable," said O'Grady, who laos has won two world track cycling titles in the Team Pursuit in 1993 and 1995.

"I've jumped out of planes, been in a Russian fighter jet, a V8 Supercar, the works - but the twin seater Ducati blows them all out of the water!

"I have never come close to the experience of hanging on for your life.

"The braking on those bikes had my feet coming off the rear pegs, and my butt way off the seat, the acceleration meant I needed my full strength to hang onto the machine and not get flicked out onto the track in front of 90 thousand fans," he explained.

"It was something I will never forget and would do again tomorrow if my body could handle it."

But during his almost two decade career at the top level of professional cycling O'Grady has had more than his fair share of injuries.

In the past he has broken numerous bones, been treated for an abnormally high heartbeat and had surgery to repair a blocked artery.

In 2007 a high speed crash during the Tour de France left him with five broken ribs, a broken shoulder and a punctured lung and earlier this year he was sidelined due to injuries sustained in a crash during the Milan - San Remo event.

So from O'Grady's perspective this latest incident is nothing to be concerned about.

"It takes more than one lap to get rid of me," said O'Grady.