They arrived in huge numbers on shared bikes after pedaling 30 miles in the evening chill, pumped by the adrenaline of youth and the thrill of embarking on a spontaneous adventure with friends.

The students would emerge on their bikes, in the tens of thousands, seemingly out of nowhere. Like a flash mob on wheels, they rode for hours in the night, by the light of streetlamps, sometimes bursting into verses of the Chinese national anthem.

The collective cycling trend has been a hit with university students in Henan, where groups of students big or small set off on shared bikes late at night and pedal for over five hours to cover the 50-km stretch from Zhengzhou, the provincial capital, to the city of Kaifeng.