Simona Mastroianni's eyes filled with tears as she recounted the call she received from her son seven weeks ago.
"I don't want to even think about what I heard that afternoon. It was quite a traumatic experience," she said.
The 14-year-old was riding pillion on an illegally modified e-bike in the New South Wales Illawarra region when his foot became caught in the chain.
His shoe and sock were ripped off, and the chain sliced through his left heel.
"It could have been worse. He's really lucky he's not a foot amputee," Ms Mastroianni said.
But her son's heel was almost entirely severed. He faced a long recovery with frequent trips to Wollongong Hospital and weeks off school.
Modified e-bikes are illegal in NSW. (ABC News: Ashlin Blieshke)
New laws introduced in March limit the maximum motor-assisted speed of e-bikes to 25 kilometres an hour, with the throttle required to cut out at 6km/h unless the rider is pedalling.
Ms Mastroianni said she had previously bought an e-bike for her son which was easy to modify, but after witnessing the damage she urged other parents to "think long and hard" before doing the same.
"They're pretty much like a motorbike at the end of the day," she said.
"I don't think kids that are 13 or 14 years old have the capacity or cognitive ability to understand the impacts that can happen from riding them."
More than a dozen people told the ABC they had also been injured on or by e-bikes they suspected were illegal on the NSW Illawarra coast.
Two mothers said their toddlers had been hospitalised with broken bones when they were struck in separate incidents on a shared path along Wollongong's coastline.
Former ABC presenter Margaret Throsby was also struck and badly injured on the same pathway.
Trauma admissions rise
The co-director of trauma at Sydney Children's Hospital, Donovan Dwyer, said the network's hospitals had recorded a "dramatic and worrying" increase in trauma admissions from e-bike injuries.
Donovan Dwyer says there has been a "dramatic" increase in e-bike injuries. (ABC News: Simon Amery)
"The more serious injuries can be life-threatening and life-altering," he said.
"These children are riding bikes that behave very similar to motorbikes, but a bicycle or helmet is not going to afford you the same protection, particularly when you're going at those speeds."
The NSW government promised to crack down on e-bikes.
By early 2029, the maximum wattage of the electric devices will be halved to 250 watts, and an age limit is under review.
New laws introduced in August allow Transport for NSW and police to seize and crush non-compliant devices; by October, 58 bikes had been removed and 22 crushed.
David Driver says police will begin a more widespread crackdown on e-bikes. (ABC News: Simon Amery )
Highway and Traffic Patrol head Assistant Commissioner David Driver said that would be expanded.
"We just want to make sure that we've got our processes right before we scale it up," he said.
He estimated there were 750,000 e-bikes in NSW but said it was impossible to know how many of them exceeded legal speed and power limits.
Different approach
Bicycle NSW's Peter McLean said the police crackdown sent a strong message, but it remained too easy to buy or import illegal or easily modifiable e-bikes.
Peter McLean wants the distinction between legal e-bikes like his and illegal devices made clearer. (ABC Illawarra: Penny Burfitt)
"It doesn't make any difference crushing [these] bikes because there are thousands and thousands of these devices out there," he said.
"We need to be looking at the start of the pipeline, turning that tap off at the border so these bikes aren't coming into the country in the first place."
In NSW it is illegal to ride a non-compliant e-bike in public, but it is not illegal to buy or sell them.
Mr McLean feared the proliferation of illegal devices was casting a shadow over legal e-bikes, which he said can be life-changing transport options for teenagers and seniors.
"We want to see targeted approaches to drive a big wedge between what's legal and what's not," he said.
"It is very safe for a teenager to be riding a legal, compliant, safe e-bike."
Ms Mastroianni said she wanted to see reforms like registering or licensing e-bike riders, including teenagers, considered alongside the police operations.
"It's very easy to buy them, it's very easy to modify them," she said.
"I think they need to look long and hard at the manufacturers and people producing them."