Britain's Dame Sarah Storey failed in her attempt to break the women's hour record at the London Olympic velodrome.
Storey rode 45.502km, to set a British and Paralympian C5 best, but Dutchwoman Leontien Zijlaard-van Moorsel retains the record of 46.065km set in 2003.
The 11-time Paralympic champion, 37, was ahead of schedule early on but fell behind after 30 minutes and dropped further away to finish 563m adrift.
"It was definitely the hardest hour of my life," Storey said.
"I came in here hoping to go further than 46km, but to break the British record, I'm really chuffed.
"It's not as far as Leontien but to miss out to her is no bad thing."