A cyclist caught not wearing a helmet will have to cough up $344 in fines - that's $60 more than the government slugs a driver travelling 20km/h over the speed limit.

Since the government increased the fines in 2016, the revenue brought in by pinging cyclists for not wearing helmets has skyrocketed.

In 2014-15 the total revenue was $197,000 while the last financial year brought in more than $2 million - that's a 940 per cent jump.

The high fine has been criticised by University of Wollongong Associate Professor Julia Quilter as "over the top".

However Transport for NSW said the increase in the amount of the fine was due to "known safety risks, offence data and community and stakeholder feedback".

Those offences that were deemed to carry a high road safety risk saw the fines raised.

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Transport for NSW said the fine for a cyclist not wearing a helmet was now the same as a motorcyclist not wearing a motorcycle helmet.

While the cycling helmet fine was higher than some speeding fines, Transport for NSW pointed out that vehicle speeding fines also came with demerit points while cycling fines did not.

Data from Transport for NSW showed that at the time the decision to raise the fine was made, there had been 49 cyclists killed in road crashes between 2011-15.

Of those 12 were not wearing a helmet - or 24 per cent.

Over the same period, of the 1674 cyclists who were seriously injured in a crash, 298 did not have a helmet on.

"Cyclists are some of our most vulnerable road users as they don't have the protection of a vehicle in a crash," said Centre for Road Safety executive director Bernard Carlon.

"Research shows that helmets reduce head injuries by up to 74 per cent in crashes with motor vehicles.

"Everyone at every age should use an Australian standard bicycle helmet."

He added that a bicycle helmet not correctly fitted and fastened would not provide enough protection in a crash.