Cheap thrills and escaping on high-speed bikes have made bikers, mostly in the age group of 18-25, a terror for the people of Kolkata, police officials said.
A French woman staying at Jodhpur Park in south Kolkata was recently molested at night by one such gang.
Gang members also beat up a man accompanying her when he protested.
"I live in Behala. There have been incidents when I face harassment at the hands of bikers while returning home late at night," said a woman banker.
From busy Metro stations to bus stands, roads and in autorickshaws, molesters and eve teasers seem to be on the prowl every where.
Kolkata police, to tackle the menace, have launched night-long offensives on weekends against molesters and biker gangs in various parts of the metropolis including important junctions such as J L Nehru Road, APC Road, AJC Bose Road, Park Circus crossing and Lenin Sarani.
"We have kept up the tempo and are conducting such operations every night mostly on Fridays, Saturdays and Sundays," said Additional Commissioner of Police Debashish Roy.
Since July 26, over 900 bikers have been prosecuted by the police, 25 motorcycles seized and 10 bikers have been arrested, he said.
"The policing was always there. But from July 26 we started it on a huge scale, checking and nabbing rash driving and mischievous drivers on the streets in Kolkata," said Kolkata Police Commissioner S K Purakayastha.
"This increased policing ought to infuse a fresh sense of safety and security among women and strike fear among the biker gangs," he said.
The campaign, besides weekends, would also be carried out on week days for an element of surprise, he said.
Police sources said that sufficient number of policemen would be stationed at key intersections and mobile units would keep watch on a three km radius in north and south Kolkata, while videographers would accompany night patrols.
The police have also decided to install new cameras in various parts of the metropolis to photograph errant bikers.
Policemen are also being trained by two BPOs to handle calls on the 1091 helpline numbers.
After a call on the helpline, the police would guide the victim to the nearest police station or a mobile unit would be dispatched to the area if that was not possible.
According to police officials at the Lalbazar headquarters, incidents of molestation in the city at the hands of biker gangs have come down in the last few days.
The state had topped the chart in crimes against woman, according the National Crime Records Bureau Data, which reported 30,942 incidents of crime against women in the state in 2012 against 29,133 the year before.
This figure had been contested by the West Bengal government.
NOTE: Picture used only for representational purpose.
Photograph: Saad Shalash/Reuters