When James Cracknell was hit by a truck in July 2010 while cycling as part of a journey across America, the two-time Olympic rowing champion faced a fight for life, rather than cycle, run, row and swim 2,500 miles in just 18 days.

The 38-year-old suffered a contre-coup injury – having been hit by the truck’s wing mirror at 75mph, the force of the impact smash his brain against the frontal lobes, fracturing his skull in two places.

The frontal lobes control the personality and Cracknell’s live has been changed irreversibly. There have been times when his behaviour has been so erratic, he hasn’t been allowed to be alone with his two children.

But, just six months after the accident, Cracknell was back on the bike, lining up to face the Yukon Arctic Ultra – a 430-mile race, on foot, on skis or by mountain bike, up the frozen Yukon river in north west Canada. Cracknell, a self-obsessed cycling addict, chose to ride the full route by mountain bike.

“Some questioned the wisdom of this, not least because of the serious cycling accident I suffered in America last July, but at least there wouldn’t be any trucks for me to hit this time,” wrote Telegraph columnist Cracknell.

“A number of things in my life have changed since the accident. These are difficult to discuss and almost impossible to convey through mere prose, but I felt that a return to competitive cycling would be good for my self-confidence.”

Cracknell’s journey, The Coldest Race on Earth, was broadcast on the Discovery Channel last night. It was the third in a trilogy which first documented Cracknell’s participation in the Marathon des Sables, six back-to-back marathons across the Sahara Desert, before revisiting Route 66, where he suffered his accident.

And despite also previously rowing across the Atlantic and taking part in the Amundsen Omega 3 South Pole Race, both with Ben Fogle, Cracknell now faced his biggest challenge – not least to find a bike fit for the ride.

“The biggest manufacturing specialists are Surly and Fatbike and their standard blueprint includes enormous forks to house big, fat rubber – their 100mm rims with low-pressure tyres would look at home in a motocross paddock,” wrote Cracknell.

“Geometry has to be conducive to comfort and stability, due to the length of time spent on the bike, so an aggressive drop from seat to bars is a no-no. My Fatbike 9:Zero:7 (it takes its name from the dialling code for Alaska) had an upright riding position, which reduces stress to the neck and wrists and meant that I was able to ride for longer periods.

“It also had a low crossbar – a vital touch, because cycling in snow involves plenty of mounting and dismounting.

“A massive downtube is essential for winter expeditions, because the bike needs be fully loaded for survival in extreme conditions. Food, sleeping bag, stove, fuel, spare kit, lights, tools, spare tubes and goggles all have to be carried.

“Other competitors seemed to do a better job of packaging their kit, but while I was paying attention to that I consciously avoided checking out rivals’ gear ratios – I had given the subject considerable thought and didn’t want to be plagued by seeds of doubt while I was battling sub-zero temperatures.”

It’s a dilemma that many of us have faced. Do I have enough gears? Am I being too conservative? But the local trail centre won’t present waist deep powder and temperatures as low as -50c.

“I decided to dispense with the biggest chain ring, because it wouldn’t be seeing much action, and opted for light, battle-hardened Sram XO componentry, with two chain rings (33 and 22 teeth),” he continued.

“At the rear I had a nine-speed cassette, but removed the second smallest sprocket to allow room for the chain to clear the tyre in the highest gear. Snowbikes are unlikely to set records, anyway – 10mph is considered fast and 6mph respectable.

“Finishing being the main objective, I wanted the bike to be as reliable as possible and chose Shimano XTR pedals and a Sram XO twist shifter, which allowed me to change gear while wearing thick mittens.

“I went with a 100mm wheel rim at the front and 80mm at the back – larger at the front to support the weight of the kit hanging from the bars, smaller at the rear to aid traction.

“My speed wasn’t an issue, I arrived first at the 100-mile checkpoint, but it helped that we’d set off 24 hours after the annual 1,000-mile Yukon Quest dog sled race, which had compacted the snow.

“Despite looking ungainly, the bike handled neutrally and it wasn’t until I left a frozen river and headed into the forest that I encountered deep powder and steep, kicking climbs that regularly had me eating both snow and humble pie.
“Apart from a broken chain, which required a hasty conversion to a single speed for the final 40 miles, the bike performed magnificently. I only wish I could claim the same about the rider.”