Motorists in the Sydney CBD and Frenchs Forest are most likely to be fined for not giving cyclists enough space, new data released under freedom of information laws shows.

There were 1967 cyclists seriously injured across NSW last year, and the trend has worsened since 2005.

David Maywald is a member of the Dulwich Hill Bicycle Club. Credit:Brook Mitchell

Dulwich Hill Bicycle club member David Maywald said despite safe-passing rules introduced in March 2016, cyclists have had to take "enforcement into their own hands" by building devices to check how close vehicles pass. A petition asking NSW police to enforce the rule has already gained thousands of signatures here.

"The burden of evidence and prosecution has fallen onto the victims of dangerous close passes," Mr Maywald, who has lodged FOI requests about the issue, said.