A fitness enthusiast who died after losing control of her bike and careering into a house may have suffered "cyclist's palsy", a coroner has said.
Rebecca Scott, 24, was travelling down a hill in Branscombe, Devon, in training for a 100-mile endurance ride, when she veered into a wall of the property.
Her father, Alan Scott, an IT consultant, was cycling behind his daughter and heard a "bang" as she crashed into the wall, suffering multiple injuries.
An inquest heard there was no mechanical fault with Miss Scott's bike and the triathlete was described as a "competent" and experienced rider.
Andrew Cox, assistant coroner for Exeter and Greater Devon, recorded a conclusion of accidental death during an inquest at Devon County Hall today.
"Nothing I have heard today suggests this was anything other than a perfectly sensible, well organised, family cycle," Mr Cox said.
"I accept there is nothing from a mechanical perspective to explain what has gone on here, which means we are at something of a loss to find anything as the cause.
"The issue of cyclist's palsy, which I have not come across before, has been raised. It is speculation and there is nothing a pathologist could find at post mortem.
"It is, I think, the best explanation for what has happened, but I cannot say for definite that it did happen."
Cyclist's palsy, also known as handlebars palsy, is a numbing of the nerves in the hands after cycling in the same position for a extended period of time.
Mr Scott, of Clyst St Mary, near Exeter, told the inquest he went on a training ride with his daughter at about 12.15pm on August 3 last year.
The pair had enjoyed a "social" ride for about an hour before they tackled a long, steep hill down into Branscombe.
During the ride, Miss Scott said she would ask her brother Matthew to "tweak" her brakes later, but did not complain her bike was broken, Mr Scott said.
"Rebecca was never reckless with the downhill speed," Mr Scott said. "We weren't racing at all, there was nothing like that going on.
"I was in front, I rode with my fingers on the brakes all the way down. Then, near the bottom she went past me, which was unexpected.
"She was making a noise. I knew she wasn't happy. At that point, I released my brakes to chase and catch up with her.
"She went past me, around the corner out of sight. I then heard a bang and that was it - no time at all. I was there seconds later."
Paramedics were called but could not revive Miss Scott and she was pronounced dead at the scene.
She had hit the wall of a house at the bottom of the hill and suffered "multiple injuries", pathologist Dr Paul McCullagh said.
John Snow, a vehicle examiner for Devon and Cornwall Police told the inquest there were no mechanical defects with Miss Scott's bike.
Pc Rod Lomas, of Devon and Cornwall Police, suggested cyclist's palsy could be to blame for the tragedy.
Mr Lomas said the condition is caused during long cycle rides, when cyclists do not change the position of their hands - causing tingling, fatigue and numbness.
"It is just a possibility to try to explain why Rebecca has lost control and has been unable to control the speed at which she has descended," he said.
"It is something that is rectified by changing the position of the hands."
Mr Lomas said it would have taken "some bottle" for Miss Scott to change the position of her hands while out of control on the hill.
He said "cyclist's palsy" could have left her unable to squeeze fully on the brakes, meaning she could not slow down.
The coroner added: "This just seems to me, on every angle, to be an absolute tragedy of a young, fit woman doing something she enjoyed with a family that she loved."