She pulled over and yelled to her daughter to call 111.
"When I approached him I didn't know if he was dead or unconscious. I actually thought he was dead," O'Callaghan said.
"Then he came round and was really confused ... didn't know where he had come from."
Meanwhile one of her friends waved cars to slow down, while another stayed on the phone with St John until the ambulance arrived.
The man, who lives near Warkworth, then started moving and talking to her.
She said he was confused and asked her about six times how she had found him. He didn't know where his wife was or her phone number.
While it was unclear what happened, O'Callaghan said it looked like he had flown over the front of his handlebars and landed on his head. His helmet had three cracks on it.
"From the look of his bike, his handlebars were scratched upside down so I think he went over the handlebars. Whether he braked or whether he had a stroke - I don't know what happened."
O'Callaghan waited with the man for about 20 minutes until St John arrived and transported him to North Shore Hospital.
She called the hospital last night to check how he was, but said he did not remember them helping him.
"He kept saying how did I end up here. He didn't know anything about it."
The ambulance could not take his bike so the group left it with Barfoot and Thompson which was the agency they had planned to view the house through because the Warkworth police station was closed.
O'Callaghan said they were all so shocked after the event that they didn't make it to the house viewing. "I was shaking even two hours later because I was so convinced he was dead."
