The family of a 78-year-woman killed by a teenager on a scrambler bike as she crossed the road say police need more powers to tackle illegal use of the off-road vehicles.
Last month a 14-year-old boy was sentenced at Liverpool Crown Court to three years detention after he admitted causing the hit-and-run death of grandmother May Laidlaw by dangerous driving.
Mrs Laidlaw was struck as she crossed the road underneath the flyover at the junction of Queens Drive and Moor Lane in Walton, Liverpool, on the afternoon of December 2.
The bike was not roadworthy and had a flat tyre, no front or brake lights and no speedometer, while the uninsured rider was not wearing a helmet.
Mrs Laidlaw's family believe parents should take more responsibility and not allow children to buy the bikes in the first place.
Her daughter, Heather Bush, told the BBC Inside Out North West programme: "They're letting them go out on the road. They must know and they must be held responsible.
"We want to show people what these kids are doing. Don't let them out on their own. Don't buy your kid a bike if you know that that they're going to do the wrong thing with them."
She said the sentence of her mother's killer was not harsh enough.
Ms Bush said: "He's ruined everything about our family. I never went a day without speaking to my mum. She only lived over the road.
"They must know that one day they're going to hurt someone, or themselves."
Mrs Laidlaw's husband of 58 years, Tommy, 78, added: "If parents are buying these bikes, they should be charged as well.
"I don't know how they'll (the police) do it but they've got to do something. It's the people the riders hurt who suffer. I know they've seized a lot of the bikes, but they're still out on them."
Merseyside Police has arrested more than 100 people and seized 300 off-road bikes in its recent Operation Brookdale campaign, crushing scramblers found to be ridden illegally.
Assistant Chief Constable Ian Critchley said: "We have licensing around areas such as firearms and I believe that while there is law around on-road bikes it's too easy to be able to purchase an off-road bike that in itself is a weapon.
"I also have concerns about protection of my officers and the law around them being able to make some really tough decisions.
"I think the law does not best protect our officers at that moment in time to make those decisions. That's something that we're talking to the National Policing League and our local MPs about."
- BBC Inside North West is broadcast on BBC One North West on Monday March 5 at 7.30pm.