"I hopped out of my car and called 111 and started slowing down traffic. People came running out of the homes to try help the young man on the bike, giving him chest compressions," Clair said.
"There were a lot of people yelling to 'help him, help him,' but there wasn't much that could be done."
Clair said emergency services showed up within minutes.
"I feel sorry for the truck driver. There was nothing he could have done to avoid it. I hope in his head he's all right."
Rotorua Fire Station officer Barry Hogan said: "When we arrived with the ambulance they determined the person was critically injured."
Hogan wasn't aware the person had since died.
A man was seen praying at the scene roughly 40 minutes after the incident.
The accident followed three major crashes in the North Island on Friday.
A child was killed after a crash on the Desert Rd in Waikato about 3.30pm Friday.
One person injured in the crash remains in Waikato Hospital's high dependency unit.