While the vast majority of public and private agencies' attention goes to directly reducing number of vehicles purchased, vehicle miles traveled (VMT), gallons consumed, or greenhouse gas emissions, an equally valid (an quite inexpensive) option for larger and denser cities is bike-sharing to reduce emissions.
Bicycles are one of our oldest and most enduring forms of carbon-neutral transportation. But why are they not more widely used as a way of getting around urban areas?
First, there is the expense factor. Many people would rather not pay for the expense of owning a bike, particularly a bike that will last. Owning a bike incurs maintenance costs that some would rather not take responsibility for. Also, city-dwellers often live in cramped apartments with no room for a bike. Others are worried for their safety when they are cycling in the streets, as often there are no shoulders or bike lanes to accommodate them. Finally, many people simply do not find it convenient to ride bikes to their destination.
Public agency fleets can lead by example by first starting their own bicycle fleets available to employees (for light-duty tasks) free of charge. Public employees are often highly visible in the city center, and an agency bike-sharing program can help promote safe bicycling practices as well as build a rapport with the community. As soon as the city develops a good relationship with a bicycle manufacturer, it can develop a bike-sharing program for the general public for a small fee. Bicycles would be a fixed public amenity available for temporary use by residents or tourists throughout the city, like library books.
After resounding success in Paris, London, and Barcelona, bike-sharing has finally caught on in the US. Washington DC and Boston now both boast highly-regarded bike-sharing programs.