In 45 days, he says, he covered more than 16,000 kilometers, traveling through 13 provinces and autonomous regions and 28 cities, including Hebei, Gansu, Qinghai and Xinjiang. When he passed through Lanzhou in Gansu province, where he had been four years earlier, he found the city had greatly changed, he says.

"In 2011 it was a very poor place, but now it's rich. There are quite a few multinationals and famous international hotels, as well as luxurious cars. The high-speed train has brought many development opportunities to the province."

He immensely enjoyed the scenery along the way and made friends, he says, but when he posted photos on Facebook his friends "thought it was dangerous to ride a motorbike in a foreign country", particularly after he had an accident and broke his left leg.

"It was on July 24 when I had almost finished the trip. Usually I did not ride on highways because in China that's not allowed. So I took national roads. But after I had just passed the provincial boundary between Inner Mongolia and Hebei provinces the wheels slipped on the gravel (and) I fell down and broke my leg."

Lying on the road, he could not move enough to reach his mobile phone, and he yelled for help, but more than 40 vehicles passed without stopping, he says.

"Some slowed down to take a photo of me," he says, adding: "I'm no swindler."

Help eventually arrived and after being taken to a local hospital that had not pain killers he was taken by ambulance to Beijing, an excruciatingly painful journey through traffic jams that took five hours.

"I chewed a lot of biscuits," he says.

As he talked to China Daily, his leg was still in bandages, which were to be removed two days later, before he returned to the US.

"My friends think it was dangerous ... but I think it's great fun. Next time I plan to ride from Beijing to London, and I will change to another route, going down to Guangdong and Guangxi, entering Tibet and going to Pakistan."