The Nanjing subway's ban on folding bikes and food on trains beginning next year has sparked a heated discussion among the public.

The Nanjing subway's operating company said that more than 600 commuters carry folding bikes on trains every working day, but only 4.1 percent of those passengers fold the bikes before boarding the train.

"Under a transportation regulation issued in 2009, commuters in Nanjing should not bring unfolded bikes to the subway, but many people are not aware of the rule," said an official with the operating company who asked to remain anonymous.