A 65-year-old man from New Zealand died suddenly on Saturday while taking part in the Motatapu mountain bike ride between Wanaka and Arrowtown.
Event organisers have not released any further details about the athlete or his family.
Motatapu spokesman Andrew Dewhurst said the organisers were "deeply saddened to confirm the death of one of our athletes at [Saturday's] Motatapu multi-sport event".
A police spokeswoman said an athlete had collapsed and died. There would be no police investigation.
"We were notified just before 12 [noon] by means of a personal locator beacon. The person had passed away and it looked as though it was a medical event. It has been classified as a sudden death," she said.
A St John spokesperson said the man was found dead at the scene.
There were several other accidents on the mountain bike course.
St John ambulance clinical control reported about eight people were flown to Lakes District Hospital suffering from various injuries and ailments.
The most seriously injured was a person with a broken leg.
A St John spokeswoman said the patients were all flown from the course because it passed through remote high country on Motatapu, Mt Soho and Glencoe stations and was difficult to access by road.
The Motatapu event offers a range of running, triathlon and mountain biking races, five starting at Glendhu Bay in Wanaka, and one starting in Arrowtown. All events finish in Arrowtown.
Conditions on Saturday were cool in the morning, but soon heated up with temperatures reaching the mid-20s.
