Furious Australian cyclist Baden Cooke refused to accept race leader Paolo Bettini's explanation after a high speed crash cost him a likely stage win in the Tour of Italy.

Italy's Olympic road race champion Bettini initially threatened to quit the race after being relegated from stage winner to fourth for "irregular sprinting" in the incident which put Cooke into the barriers less than 100 metres from the line.

Cooke, a former sprint category winner in the Tour de France, was following Bettini's wheel as they headed over the small climb towards the finish of the 220km fourth stage in Frosinone.

But just as the Aussie went to pull left in an overtaking move, Bettini also veered to his left.

Cooke tried to force his way through, but hit the barriers with his left shoulder and went flying spectacularly over the handlebars.

Relatively unscathed, Cooke walked to the finish line without his bike, certain he should have joined countryman Robbie McEwen as a stage winner in the 2005 Giro d'Italia.

Seconds later Bettini approached to explain his actions, but Cooke was having none of it.

"I got over the hill no worries. None of the sprinters were left, I got on Bettini's wheel, he hit out early, I gave him a length, and I was absolutely cruising," Cooke told cyclingnews.com.

"(I) dropped it down the gears, ran at him, just about to blow his helmet off as I went past him... and he's just turned left and put me in the barrier.

"I had it won, I was just about to throw my hands in the air. Instead I did five somersaults down the road."

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