Sydney is one of the developed world's most hostile cities for cycling, according to a US academic who spent a sabbatical year researching ways to boost bike-riding levels in the city.

''I did not cycle that often because I almost got killed several times - people cutting me off, squeezing me off the road and not stopping,'' John Pucher said of his efforts to ride to Sydney University from his Stanmore home.

Born to ride ... traffic in King Street, Newtown. Credit:Kate Geraghty

''Whether I was a pedestrian or cyclist I found the level of the hostility of enough Sydney motorists worse than I had seen anywhere in the world.''

For decades Dr Pucher, from Rutgers University in New Jersey, has been riding bikes - from the cycling wonderlands of Amsterdam and Copenhagen to the car-choked streets of many US cities. But he was still stunned by his experience here.