Expanding bike lanes, handing out free helmets and making lessons free: New York is making great strides in encouraging pedal power at the expense of exhaust fumes, even if some cyclists are still nervous about navigating bottleneck traffic.

For years, the city of 8.5 million -- which has the most extensive public transport network in the United States -- stood and watched the bike boom take off in European capitals.

In 2013, then billionaire mayor Michael Bloomberg launched the Citi Bike sharing scheme and since then, New York has seen the fastest growth rate in cycle use of any big US city.

"The city has come a long ways in terms of having a much stronger commitment to promoting bicycling," says Rich Conroy, education director for Bike New York, a non-profit organization that encourages safe cycling.