http://www.bbc.co.uk/news/magazine-16345232An expedition is attempting to be the first to use a bike to reach the South Pole. It will mean tackling some of the most extreme conditions on the planet. So how can a bike manage it?
Snowdrifts, blizzards, rutted ice, altitude sickness, frostbite and snow blindness. They're hardly the odd speed bump, tree root or wayward pedestrian a cyclist usually faces on a bike ride, but this isn't an average journey.
Blue Peter presenter Helen Skelton is hoping to become the first person to use a bike to reach the South Pole. She is attempting to travel 500 miles (805km) across Antarctica and will cycle for large parts of it, as well as snowkiting and walking. She hopes to complete the trek for Sport Relief in 20 days.
At this time of year, the average temperature in Antarctica is -25C, but can drop to -50C. Severe coastal winds come from cold air flowing down off the interior ice sheet. Wind speeds can reach up to 125mph (201km/h) and average about 80mph.
The challenge
Trek starts at 83 degrees south
Will cover 500 miles (805km) to reach South Pole
Will be travelling for up to 14 hours a day
Will cover anything from eight to 40 miles (13 to 64km) a day
Will have to climb to altitudes of 3,000m (9,840ft)
Will burn up to 10,000 calories a day
In addition, she will be dragging 12.9st (82kg) of equipment and supplies behind her on a sledge.
It's no average ride and she is not using your average bike. The specially-built Hanebrink "ice bike" took designers in Los Angeles three months to finish. Dan Hanebrink and Kane Fortune have been building all-terrain hybrid bikes that can be used in all environments for many years.
They previously worked on one for explorer and polar guide Doug Stoup. He wanted an alternative to skis that could take him and his equipment across the icy terrain. He biked for 200 miles in Antarctica's Heritage range.
With the help of Stoup's first-hand experience of cycling in snow, they have fine-tuned the design for Skelton. Even so, the challenge is a first for everyone involved.
"The bike has never been tested in conditions quite as extreme as Helen is doing," says Fortune, 29.
It is designed to be as minimalist as possible, to make it aerodynamic and very low maintenance. In total, it weighs about 40lb (20kg), a lot of that weight being the fat, tubeless tyres. A standard mountain bike averages 25 to 30lb.
"It will be huge if she makes it," says Stoup, who is currently in Chile preparing to go to Antarctica for Ice Axe Expeditions. "It would be the first bike expedition to the South Pole. I get calls every day from adventurers wishing to bike to the pole, but no one has ever attempted it.
“Like Captain Scott, Helen is attempting something that has never been tried before”
Explorer Sir Ranulph Fiennes
"When I cycled in Antarctica, I was hit with an atypical storm that grounded me for five days. I experienced 100mph winds - it was epic. I still biked 200 miles and know Helen will be successful."
The presenter, who last year completed a 2,000-mile kayak trip along the Amazon for Sport Relief, has already been hit by bad weather and the start of her challenge has been delayed. She was finally able to start today.
"People keep saying a bike shouldn't be able able to make it to the South Pole, but that makes me even more determined," she says, speaking from Antarctica.
"The biking is going to be really tough. What I like about this challenge is that 90% of people know what it's like to ride a bike, so will be able to relate in some way to what I'm doing."
