Unclipping his red bicycle helmet and unfurling his sleeping mat, Xu Yunkun settles down for the night in an underground pedestrian passage near Chaoyangmen Subway Station. For the past two weeks, this has been the 67-year-old farmer's "home," conveniently located near Sanlitun's embassy district, where he is applying for visas to the Central Asian and European countries he hopes to tackle as he continues a half-decade cycling adventure.

In the eyes of his family members and friends, Xu is a "madman." At an age when most Chinese retirees spend their days playing chess or cards, Xu pedals through rain, hail or shine as part of an international cycling odyssey.

His back isn't what it used to be, and his joints are stiff from a lifetime of tending to corn and wheat crops in his native Nanyang, Henan Province. But Xu vows he'll continue pursuing his dream and spreading "positive energy" along the way, even if it kills him.

Tour de Asia

His spandex yellow shirt sticking to his skin, Xu remains energetic and upbeat as he lies down next to his trusty bike and toolkit that has helped him recover from countless punctures. Flanked by hanging placards with the slogan "nationwide fitness, low-carbon life," the bike is Xu's third since he began his epic ride six years ago.

"From 2007 to 2011, I traveled to 600 cities across China and three Southeast Asian countries [Laos, Thailand and Malaysia] on my bike. These 600 postage stamps and 4,000 photos are proof," said Xu proudly gesturing at them, which he uses to attract sponsorship for his future travels.

Despite conquering steep hills and rugged terrain on his bike over the past six years, Xu's biggest challenge has been overcoming bureaucratic hurdles that stand between him and realizing his dream.

"It's so difficult to get [tourist] visas," Xu sighed. "They (embassy staff) ask for so many documents, including from work units and property deeds. How can ordinary people like me have such documents?"

Adorning the ground and wall of the underground passage near where Xu sleeps are around 100 scenic photos of the intrepid cyclist and locals he has encountered in destinations including the Tibet and Xinjiang Uyghur autonomous regions and Southeast Asia.

"I choose to display these photos because I think people are more interested in these places, but I've traveled to many other places," Xu explained, producing a map charting his journey.

"The red points are provincial capitals. I went to all of them to signify I have been to the province. I tried to travel along the outskirts of border provinces because I wanted to 'circle' China," said, adding he either relies on hospitable locals for accommodation or else sleeps under the stars.

Between 2007 and 2011, Xu raised 100,000 yuan ($16,274) via donations from people eager for him to continue his adventure.

"But there were still times when I was short of money. I'd call home and my children would send me money to continue my trip," said the father-of-four.

Xu said he chose 2007 to begin his cycling tour because all his children by then had stable jobs and families, and no longer depended on him.

The whole country was also in the grip of Olympic fever ahead of the 2008 Beijing Games, with Xu wanting to do something to promote the event's "one world, one dream" message.

But when he told family and friends of his plan, no one understood his "weird" behavior.

Taking the lonely road

"It was like being led to my execution. My wife, children, relatives, neighbors and friends didn't understand me, let alone support me. They all thought I was a madman," Xu recalled.

Plagued by the urge to embark on his adventure, Xu struggled to sleep well for nearly a decade. "I was anxious all day. This dream had fermented in my mind for years. I was already in my 60s, and didn't want to have any regrets," he said.

Despite living a comfortable existence in a two-story house, Xu wasn't ready to embrace the carefree retiree life.

"What is the meaning of life in waking up, eating one's fill, playing cards and then going to sleep? Sure, you can do it for 10, 20 or even 30 years, but then what? Life should be more meaningful," he said.

"I was tired of the comfortable yet repetitive lifestyle. I was saddened to see neighbors and friends die suddenly of illness because they didn't care about their health. I wanted to live a healthy life and see something fresh."

The best insight into Xu's motivation can be found in one of his calligraphy works.

Accompanying his photo exhibition, it reads simply: "China dream and my dream."

"My dream is to travel the world and promote fitness and environmental protection along the way. I also want to motivate other people, so it's also related to the China dream," Xu explained.

Rough rider

While on the road, Xu seizes every possible chance to see famous landmarks.

"Before you visit somewhere, you can only imagine [what it will be like]. After you go there, you know the actual landscape, people and culture because you've seen them for yourself," Xu said.

Xu said he was most impressed by the religious devotion of Tibetan Buddhists, the simple yet honest people of Laos and the warmth of overseas Chinese in Malaysia.

But his journeys have also brought him inevitable brushes with danger. "When I was in Lop Nur (a dried salt lake in the southwest of the Xinjiang Uyghur Autonomous Region), the wind was so strong at night that I decided to camp in the lowlands," he recalled.

"One night I spotted a wild animal that I perceived to be a bear. I burst into a sweat and immediately climbed back [to the highlands]."

But such risks haven't deterred him from realizing his dream, even though he often has to "rough it" in some inhospitable places.

Whether sleeping solo in the wild or on the street, bunking down in kindhearted villagers' homes or enjoying the rare pleasure of a warm shower and bed at a hotel, Xu is content as long as he has his bike.

"I've slept in the wild, so the street is much better," he said of his underground pedestrian passage in Beijing. "My aim is to use the least money possible to travel as far as possible."