One metre up to 60km/h and 1.5 metres beyond it

New South Wales motorists will need to abide new laws about minimum passing distance when overtaking cyclists, or face fines and the loss of demerit points.

The new Minimum Passing Distance rule comes into force after a two-year trial, and mandates motorists leave a one-metre gap when overtaking cyclists below 60km/h and a 1.5-metre space over 60km/h.

According to NSW Minister for Roads, Maritime and Freight, Melinda Pavey, the two-year trial helped reduce bike-to-vehicle accidents by around 15 per cent.

"That is an indication that the trial worked, and it's not just feedback from cycling groups, it's also feedback from motorists," Minister Pavey told media.

"That's important, because when you have a law that isn't respected, that doesn't strike that balance... then you're not going the have people respect thos laws."

A report into the trial says there were no accidents or near-misses between oncoming vehicles while cross the centre line and overtaking cyclists. The report also says 81 per cent of cyclists were in favour of the rule, while 69 per cent of drivers supported it.

Drivers who pass too close face a $330 fine and two demerit points. There are some common-sense exemptions surrounding the rule: drivers will be allowed to cross centre lines and drive on painted islands to give cyclists the necessary room, provided conditions allow it.

Just 84 people were issued infringement notices during the trial period, with bicycle advocate groups arguing the law will only work if it's strictly enforced.

Bicycle NSW said the law is "a start" but "seeing this law enforced" is the next step to ensuring cyclist safety on the roads. Similar laws exist in all states and territories except Victoria and the NT, although VicRoads suggests leaving at least one metre at more than 60km/h.