Television presenter Guy Martin is attempting to set a new world record by cycling 4,802 miles around the British coast in 20 days.
The motorbike racer, who has set speed records in a variety of vehicles, said he is setting off on Sunday morning and hopes to be home by Christmas Day.
He said he wants to break the record for fastest ride around the coast of Great Britain, currently held by Nick Sanders who completed it in 22 days in 1984.
In a video message, Martin said: "We've got a big job on. Record's stood since 1984, I'm going to try and break it."
He added: "I'm setting off to try to break the record of pedalling around the circumference of England, Scotland and Wales. That's what I'm doing.
"The record, as it stands, is 22 days, I'm going to try and do it in less than that. The record's stood since 1984. No-one's broken it, no-one's come near it, so, it all starts here."
Martin has already set world records for fastest speed on a gravity-powered snow sled, fastest speed in a soap box and highest speed on a wall of death.
Earlier this year, he attempted to break the two-wheeled world land speed record in a purpose-built 400mph Triumph motorcycle, but was thwarted by conditions on the course at the Bonneville Salt Flats in Utah.