Christchurch motorcyclist Maria Grafhorst died after drifting across centre line
An experienced motorcyclist who died when she collided head-on with a car had misjudged a corner moments before her death, a coroner has found.
Christchurch accountant Maria Antoinette Grafhorst was riding in a line of motorcycles when she hit a Holden sedan travelling the opposite direction, on November 1, 2015.
The 63-year-old drifted at least 1 metre over the centre line on a difficult corner on Arnold Valley Rd, east of Greymouth, before the crash happened.
The road was in "less than ideal" condition, with poor surface friction, a hump inside of the turn and uneven seal, coroner Christopher Devonport said in findings released on Monday.
Grafhorst, who was also known as Marian, was on a day trip to Moana. She and her partner, Thomas Brown, were keen riders and travelled through Australia, Germany, the Netherlands and America together.
On the day of the crash, the couple woke early to watch the Rugby World Cup final. They met other riders in Riccarton, Christchurch, for the start of the Triumph and BSA Triples Run to Reefton for lunch.
The coroner said Grafhorst had turned into the left-hand curve on the road from the "incorrect position", about 23 metres too late, and at the "wrong speed". She abandoned the corner moments before the crash.
Other riders saw Grafhorst's bike in the air "vertical with pieces flying everywhere".
Debris from Grafhorst's crash caused fellow rider Gail Clement to be flung from her bike onto the road. She was flown to Greymouth Hospital with a broken leg.
Pathologist Brian Berkeley said the cause of Grafhorst's death was due to blood loss from the "severe massive trauma". She had multiple fractures, ruptured a main artery, severed her spinal cord and suffered "other traumatic injuries".
Trip organiser Ken Roy earlier said the loss was "absolutely devastating".
"No one can get to grips with the image of what took place. It took half a second, so everyone's just cruising along happily together and then you go around the corner and it's like an aeroplane crash."
Roy said the group went to great lengths to support the "totally distraught" car driver after the crash.
Canterbury BSA Owners Motorcycle Club president Ross McLellan said Grafhorst was a "well-respected and well-liked" member, who had a long affiliation with the club, including taking on the role of secretary treasurer.
"All the club is shattered by it, absolutely shocked."
The Grey District Council has added extra chevron signs on the corner and resealed the road since the crash.