Welsh singer Duffy's multi-million pound Diet Coke ads have enraged campaigners.
According to them, the 24-year-old singer is setting a bad example for her young fans because she is riding illegally through dark streets without lights or reflectors and is not wearing a helmet.
"Clearly, riding at night without lights is not something we could condone...it's illegal," the Daily Star quoted Roger Geffen, of the national cyclists' organisation CTC, as saying.
A representative for the Royal Society for the Prevention of Accidents said: "Unfortunately, advertisers do forget sometimes to make sure they are showing safe and legal behaviour when someone is using the road in an advert."
Road safety charity Brake, which campaigns for all cyclists to wear helmets, said: "We would like to see advertisers think about safety implications and what message they are sending out. Adverts which show people not belting up or cycling without lights may send the wrong messages out to viewers."
Wearing tiny shorts, tights and a close-fitting top, Duffy is seen jumping on to a racing bike just before a stage appearance.
Supping Diet Coke at the start and end of her trip and singing 'I've Gotta Be Me', she cycles through streets, a car park and a supermarket.
A rep for Coca-Cola said: "The advert is a fictional depiction of how Duffy might take some time out and is not intended to be a real-life scenario.
"Diet Coke would urge all road users, including cyclists, to adhere to the Highway Code and to follow safety advice from government and other relevant agencies," the rep added.