About 10,000 people pedalled in to work in Sydney during National Ride to Work Day today, Bicycle NSW's Elizabeth Hole said.

"We have contributed to less congestion on the roads today, reduced greenhouse gas emissions, and first-time cyclists are every excited they can do this," she said.

Before today, more than 60,000 people nationally were expected to participate in the event.

But organisers today said as many as 75,000 had taken part.

Sydney's Lord Mayor Clover Moore, state MPs, media personalities and police officers joined about 700 cyclists at a Ride to Work Day breakfast in the city.

The breakfast - at Hickson Road, Millers Point - was just one of many that took place as part of Ride to Work Day, which aims to encourage commuters to discover the benefits of cycling to work.

The City of Sydney was spending $30 million over five years to construct 55 kilometres of separated cycleways, Cr Moore said to strong applause from the cyclists.