A cyclist was filmed riding a bike with one hand and holding a child in the other - with neither wearing a helmet.
The man was seen peddling down a narrow road lined with parked cars in Bristol while holding a toddler on his hip.
Video also shows a silver Honda pulling out of a parking bay just as the man cycles past it.
The man and young child - estimated to be around three years old by a witness who filmed them - wore matching orange jackets, but neither had a helmet on.
The witness described the incident, which took place on December 11, as "shocking".
The 52-year-old, who did not wish to be named, said: "I was thinking this cannot be for real.
"He was cycling one-handed and the kid didn’t even have a helmet on a busy narrow road.
"The question is why? Why would you put your child in danger? Imagine if he was involved in an accident."
According to the Road Traffic Act, it is illegal to carry a passenger on a bike unless it has been specially designed or adapted for this.
The bike in the footage did not appear to fit that description.
The witness has not reported the incident to police.
Head of partnerships Jon Usher, at cycling charity Sustrans, said: "The Highway Code is clear that passengers must not be carried on a cycle, unless it has been specifically built or adapted to carry one.
"So family cycles, cargo cycles, or any cycle fitted with a child seat fit well within the law.
"We believe that it is a personal choice whether to wear a cycle helmet or not, and for parents to make that choice for their children.
"Parents should, of course, always ensure that their children are safe and feel safe when they are cycling together.
"We believe the best way to increase cycling safety would be to increase the amount of cycling infrastructure that is physically separated from motor traffic, as well as reducing the levels of traffic in residential areas," he added.
Sustrans says on its website that helmets can be beneficial if you are involved in a collision.
But the guidance adds: "It’s important to remember that cycle helmets don’t prevent collisions from happening.
"Therefore, we strongly support and focus our work on measures that help create and maintain a safe cycling environment to reduce collisions taking place.
"Legislating to make cycle helmets compulsory can discourage people from cycling."
The people of Bristol have blasted the man carrying the young child as "irresponsible" and said he was "endangering" the child's life.
Nicholas Foxwell wrote on Facebook : "As a keen cyclist I can hand on heart say that man should be in serious trouble for endangering a child and cycling without due care and attention.
"It’s people like this that give us cyclist a bad name."
And Terry Nichols added: "What an irresponsible pillock. He should be prosecuted for dangerous riding and endangering the life of a minor."
Meanwhile, Twitter user Red68 wrote: "Incidents like this one make my blood boil - but very regrettably are typical of the uncaring, dangerous and often 'couldn't give a damn' cycling community in Bristol.
"Please someone in Authority take some strong and appropriate action to bring these ne'er do wells under control."
