The "Night Riding Army", as some participants described it, clogged a highway on Friday, pictures posted on social media showed, a surge in turnout for a rolling flash mob that had been gathering riders for months.
"Last night's 'Night Riding Army' was spectacular!" one rider posted. "Two lanes were opened, but that simply was not enough: The cycling army accounted for four!"
The event was part of a trend of young Chinese traveling on the cheap - "like special forces" - and spending as little as possible at a time of scarce job prospects, when wages are under pressure.
The riders traveled on a straight road more than 60 km (37 miles) long beside the Yellow River that links Zhengzhou, the largest city in Henan province, with Kaifeng, an ancient capital famed for its soup dumplings.
The trend was set off in June, Chinese media said, after four women college students chronicled their ride on social media to eat dumplings in the morning.
"The Night Ride to Kaifeng: Youth is priceless, enjoy it in time," was the hashtag on social media for the ride, which state broadcaster CMG said tens of thousands of students had completed by the weekend.
Key to its success was a glut of shared bikes, which can be rented for as little as $1.95 a month.
Pictures posted by riders showed thousands of the bikes had overrun downtown Kaifeng by Saturday.
In addition to the traffic controls, the largest bike-sharing platforms, Hellobike, DiDi Bike, and Mobile, said their vehicles would lock down if ridden out of a designated zone, while media told the students to grow up.
"Youthful freedom does not mean following the trend and indulging oneself," one news outlet admonished in a comment.
"Kaifeng is worth arriving slowly and savoring carefully," read the headline of another.
Chinese authorities have cracked down on other spontaneous gatherings.
Last month, police turned out in force in the commercial hub of Shanghai to deter a repeat of 2023 Halloween celebrations in which some revelers wore costumes poking fun at issues such as the stock market, youth unemployment and tough Covid-19 curbs.