Kenneth McClelland, 77, of Largs, Ayrshire, who was driving a Volvo S40, overtook without properly checking on a Scottish mountain pass, where he collided with 49-year-old endurance athlete Sally Preece who was coming the other way on her bike.
Her bicycle and his car were “extensively damaged” in the crash.
She was taken to the Forth Valley Royal Hospital in Larbert, Stirlingshire, with serious injuries, and died the next day.
Mrs Preece, from Cheltenham, Gloucestershire, was a week into the nine day Land’s-End-to-John-O’Groats challenge when the tragedy occurred on 12 September last year.
The scene of the accident, Glen Ogle, on the twisting “Road to the Isles” A85 trunk route near Killin, Perthshire, was named “Scotland’s Kyhber Pass” by Queen Victoria, because of its tortuous bends and dramatic setting.
Mrs Preece had been taking part in the 969-mile Deloitte Ride Across Britain to raise money for Alzheimer’s Society.
At Stirling Sheriff Court yesterday McClelland admitted causing her death by careless driving. He admitted he had “failed to maintain proper observations, overtook when it was not safe to do so, entered into the opposing carriageway and struck Mrs Preece, who was travelling on a pedal cycle, whereby she sustained serious and fatal injuries”.
Solicitor Alexander Currie, defending, said: “This case was continued for resolution, effectively and I can confirm that Mr McClelland pleads guilty to the offence.”
He added: “It’s hoped the court will allow some time for an agreed narrative to be prepared, and I anticipate that reports will be called for in this matter.”
Prosecutor Claire Bremner produced victim impact statements from Mrs Preece’s family, which were handed in writing to the sheriff.
The court heard McClelland had no previous motoring convictions.
Sheriff William Gilchrist deferred sentence, and bailed McClelland to re-appear later this month.
After the death of Mrs Preece, who worked for Lloyds Bank, her family paid tribute to her, saying describing her as “dedicated and cheerful”.
Her sister-in-law Suzette Pennell said: “She was absolutely dedicated to anything she turned her mind to. Her family, her work and her cycling. She had put in hours of training for the cycle ride.”