Tension between drivers and cyclists boils down to a misunderstanding about what each group is allowed to do on the road, a cycling advocate says.

The number of cyclists killed in crashes on NSW roads has more than doubled in the past two years, with 14 recorded deaths last year.

It's a two-way street: Motorists and cyclists need to work out how they can better interact on the road. Credit:Kate Geraghty

On Sunday, two cyclists were knocked unconscious when they were hit by cars in separate incidents in Sydney. In both cases, the driver did not stop to help.

Both cyclists remain in intensive care in hospital, one with a broken back and the other with head and neck injuries, as police hunt for the drivers involved in the collisions at Helensburgh and Kemp's Creek.