Dozens of high-powered and illegal ebikes have been seized by police on Sydney’s northern beaches just weeks after the force was granted new powers to destroy dangerous bikes.

The operation was part of a coordinated push with the NSW government to ensure people only ride legal ebikes that have not been modified to reach high speeds.

One of the ebikes seized on Friday belonged to a 14-year-old boy from Warriewood. Police said it was capable of reaching speeds of more than 90km/h.

NSW police said they seized 36 “illegal ebikes”. The operation was launched on the northern beaches “following following recent incidents of illegal, dangerous and reckless e-bike use”.

The assistant commissioner David Driver said police would be launching more operations across the state in coming weeks.

“Most ebike riders do the right thing and comply with the rules; however, police will enforce [the] new legislation if people ride non-compliant vehicles,” Driver said on Saturday.

In late August, NSW police were given new powers to destroy ebikes capable of exceeding the legal speed limit.

Owners of seized ebikes now have 14 days to let police know whether their bike was stolen and being used by someone else on Friday.

After that two week window, the bikes will be “crushed”, the government says.

The legislation also allowed police to seize ebikes that do not cut power assistance at 25km/h, with non-compliant bikes to be removed from the streets.

The government invested in a number of “dyno units” – portable speed-testing devices – to measure an ebike’s power output.

The Transport for NSW secretary, Josh Murray, said one of the units was used on the northern beaches on Friday to inspect suspect ebikes.

“We can put an ebike on a machine and test its power and speed very quickly,” Driver said. “When they did that yesterday, the bike showed that just by clicking the throttle it could go over 40km/h.”

Ebikes have been hailed as a climate-friendly solution to city traffic congestion, transport emissions and even youth social media addiction, offering Australians a means to get more exercise and save money.

But they have come with a cost. NSW recorded 226 injuries related to ebikes in 2024. In just the first seven months of 2025, that had already to surged to 233 injuries plus four deaths.

Murray said most people were legally using ebikes but a small group ignoring the rules endangered other road users.

“We are serious about ebike safety and operations like this will continue by NSW police with support from Transport for NSW to ensure all road users are safe and complying with the state’s upgraded laws,” Murray said.

“Ebikes must behave like bicycles, not motorcycles. If your bike can operate like a motorcycle under throttle or go more than 25km/h while being powered, it is not legal to ride in public.

“Before you or your child jumps on an ebike, please make sure it’s road-legal, otherwise you risk losing the bike.”

On Friday, police issued 16 penalty notices and 46 cautions for other road offences, including not wearing a helmet, using a mobile phone or having multiple people on a bike.

The new laws were announced days after about 40 ebikes and e-motorcycles swarmed the Sydney Harbour Bridge. Footage posted online also showed riders – including those on so-called fat bikes – travelling on the Western Distributor, and performing stunts.

That incident led the federal health minister, Mark Butler, to declare ebikes a “total menace”.

“We’ve got to make sure we stop these things coming into the country [and] police are given the powers to crack down, to take them away, to crush them, to destroy them,” Butler said in February.