Cyclists have to be able to ride on sand. [Photo provided to China Daily]

Most of the roads ridden on in the DPRK are made of sand, and that can test riders' physical fitness, he says. At the moment only those who have long-distance riding experience and professional equipment are eligible to go on the tour, the tourism bureau says.

There are between 12 and 20 riders in the groups that go on the tours, and they set out on Saturdays and Sundays.

Sun Lin, 30, a Hunchun resident who has ridden professionally for three years, says he was on the inaugural tour last month.

"It was the first time I have crossed the border on bike, which made it particularly special. I had been a little worried about the sand, but it really wasn't that bad at all, and in fact a little more comfortable than riding on asphalt. There was a nice holiday feel about it, rather than the idea that it was a competition."

Sun says that for him the highlight of the trip was the hospitality and salt-of-the-earth nature of the Koreans they met, as well as the fresh air.

"To ensure everything was safe and that we had everything we needed, we had two Korean guides make the trip with us. Everything, including the food was good. The seafood and potato pie was great, and I can still taste it now."

Sun's girlfriend accompanied him on the trip.

"Road conditions were much better than we expected," the girlfriend, who did not want to be named, says. "As long as you have a bit of riding experience it's not going to be too hard for you. I've been asked about women doing the trip, and the only thing I would say is not to forget to take suntan lotion with you."

Piao says cyclists have warmly welcomed the tour and it has been oversubscribed for this month.

"For me one of the most gratifying things is that we are getting all sorts of people - men, women, the young, the old and the retired - who are interested in coming along."