An endurance cyclist is aiming to set a new record for the quickest 1,700-mile journey from Land's End to John O'Groats and back again.
Chris Hopkinson hopes to better the current time for the so-called "Lejogle" of five days, 21 hours and eight minutes, set in 2010.
The 45-year-old music teacher from Richmond, North Yorkshire, sets off from Land's End tomorrow and is using the record attempt to raise awareness of the Royal Signals Benevolent Fund.
Mr Hopkinson expects to get less than three hours of sleep a day during the journey, as well as battling against unseasonably cold weather and high winds.
After preparing for more than a year, the rider, who took up cycling as a way of commuting to work, is hopeful the gruelling challenge will aid his attempt to complete this summer's epic west-to-east Race Across America (RAAM).
Speaking ahead of the record attempt, the father-of-two said: "People keep asking me why I am doing this.
"The answer is simple, what better way is there to train for a 3,000 mile RAAM bicycle race?
"Mind you the weather is going to be slightly different. We currently have snow and strong winds which are expected to last, but I'm prepared.
"I just hope the crew can stay warm."