The number of cyclists killed in crashes on NSW roads has more than doubled in the past two years, prompting a renewed plea for better co-operation between cyclists and motorists.

A 40-year-old female cyclist became the latest casualty when she was killed in a collision with a Kenworth truck on the Princes Highway in St Peters on Tuesday.

Matthew Fitzgerald: Hit a rock on the road.

The woman was believed to have been riding south along the busy thoroughfare about 11.10am when her bike and the truck collided near the intersection with Talbot Street.

She was taken to the Royal Prince Alfred Hospital in a critical condition, but died a short time later.