Motorcycle legend Robert Dunlop died when he inadvertently hit the front brake of his bike when his engine seized at over 150mph during a practice session for last year's North West 200 road race in Northern Ireland, a coroner found today.
The harsh braking hurled Dunlop over the handlebars and a rider he had just overtaken ran over him before himself crashing and suffering severe injuries.
Because of injuries suffered in a previous crash Dunlop had a modified braking system on his 250cc bike which had initially been frowned upon by the motorcycle authorities, the inquest heard.
The 47-year-old five times world Formula One champion and winner of 26 races at the Isle of Man TT had expressed concerns about his bike possibly seizing after a previous practice two days before and ordered modifications.
He was on one of the fastest stretches of the circuit in Co Londonderry for the first time after the changes had been made when he crashed in May last year.
The inquiry was held in Coleraine through which the annual race passes. His widow Louise found it too difficult to attend and the couple's biker sons Michael and William attended but left halfway through the hearing, clearly distressed.
Other members of the family remained and it was left to Dunlop's twin sister Margaret Rodgers to give coroner John Leckey formal details.
The inquest heard Dunlop had only ridden the Honda for two laps during the previous practice two days earlier because it was not running as he wanted.
Good friend John Kennedy who had gone to the meeting with him said: "The 250cc bike had given him some concern. He said it was only when he was going flat out in top gear, he was concerned that the bike was hesitating and then going forward again - as if it was going to seize, but it didn't."
He said it had only happened on the fast run in to the bend at Mathers Cross - the spot where the engine did seize causing his death two days later.
Because of previous injuries which at first put him out of racing before he made a comeback Dunlop had modified the braking system to the front wheel by operating a thumb operated wheel brake on the left handlebar sited below the level of the clutch lever.
The coroner said: "I have concluded that what happened was caused by him inadvertently applying the brake lever using his left thumb as he was attempting to apply the clutch."
Mr Leckey went on: "This would have produced a powerful and instant braking effect on the front wheel and that is the explanation for him somersaulting over the handlebars.
"I am conscious of the fact that bearing in mind the speed he was travelling at he had to respond instantly.
"Therefore, the modifications to the front wheel braking system and, in particular, the location of the left thumb brake lever are likely to have been factors in the tragic sequence of events."
Mr Leckey said the inquest was a particularly sad occasion recalling as it did "the tragic death of one of the most famous sports personalities to come from Northern Ireland. He was known to everyone, as was his late brother".
Brother Joey Dunlop died while competing in a race in Estonia in July 2000.
Racer Denver Robb whom Dunlop had just overtaken before crashing said: "He was flying. I would have thought he was on a 600cc machine. Suddenly smoke came out of the exhaust and the back wheel locked and Robert went over the bars."
Darren Burns, who was also overtaken, said they were doing about 155mph when Dunlop's engine seized. "It was almost like Robert hit a brick wall I ran into the back of Robert's bike, I had no way of getting around him. The next thing I remember was coming around in hospital suffering from multiple fractures."
Asked by the coroner how his recovery was coming along he said he was doing well and would be competing again in the North West 200 this May.
Aerial footage of the actual crash was played to the court - only after most of the Dunlop family had gone outside - and several bikers said the one thing that should never be done when an engine seized was for the front brake to be hit because of the likelihood of being hurled over the handlebars.
Tony Harvey from the Motorcycling Association of Ireland who prepared a detailed report for the coroner on the crash said Dunlop had been concerned about his engine cutting out on a previous outing and had gone into the pits to have it adjusted.
He revealed that after Dunlop had come back to racing his modified front braking system had been "initially frowned upon as not safe".
However, once it had been approved he had gone on to win many local, national and international races and had been impressive on his 250cc Honda at a race meeting two weeks before the North West 200.
He said: "Robert was one of Ireland's greatest sporting legends. Robert Dunlop was not only a sporting legend but a sporting hero and a sporting ambassador.
"Robert Dunlop was without doubt a motorcycling icon who set the standards in a highly risky sport."
Emerson Callender from the Northern Ireland Forensic Service examined the bike after the crash and said the pistons had seized. He described two-stroke engines as "quite fickle".
He said they could provide years of trouble-free service but when they were highly tuned difficulties could occur. "You have to give up a bit on reliability to get more power," he said.
The coroner asked whether sensors such as those installed in cars could not be put on the two-stroke engines but Mr Callender said because of their high emission level two-stroke engines had fallen out of favour with manufacturers who were no longer carrying out engine developments, preferring to concentrate on four-stroke fuel-injected machines.
Mr Leckey recorded that Dunlop died from multiple injuries in Coleraine hospital shortly after his crash. He said he saw no point in publicly detailing the exact injuries.