Bay adventurer Samuel Gibson was not wearing a seatbelt before a fatal fall from his wheelchair during a marathon in Hawke's Bay on May 16.
Coroner Chris Devonport today released the report into the death of the popular father and businessman.
The report said those who came to assist him at the time of the accident saw he was conscious, with Mr Gibson talkative and admitting he was "a bit shaken up" after falling from his wheelchair.
On arrival at Hawke's Bay Hospital's Emergency Department, the 39-year-old, who had a rare brittle bone disease, increasingly lost consciousness and died two days later.
Severe traumatic brain injury was found as the cause of death.
Friend and director of Metalform, Bryce Easton, said Mr Gibson was "not a fan of seatbelts on wheelchairs." He said he suspected his friend had removed the seatbelt altogether.
Other witnesses to the scene also said it appeared he had not been wearing a seatbelt during the race.
An expert claimed the wheelchair may have malfunctioned, specifically cable failure "due to fatigue", which could have caused the wheelchair to stop suddenly.
On May 20 about 700 people gathered at Havelock North's Riverbend Bible Church to attend his funeral service.