(Facts from the “bicycle” chapter of Seven Wonders for a Cool Planet)

* The bicycle is the most efficient vehicle ever devised; a human on a bicycle is more efficient (in calories expended per pound and per mile) than a train, truck, airplane, boat, car, motorcycle or jet pack.

* Nearly half of all trips in the US are three miles or less; more than a quarter are less than a mile, distances easily covered by bike while saving you money and getting you fit.

* Every mile traveled by bike rather than by car keeps one pound of climate-damaging carbon dioxide out of the atmosphere, while reducing cash draining stops at the pump.

* Bicycles outnumber automobiles almost two to one worldwide, and their production outpaces cars by three to one.

* Of all the trips in the United States, just two-thirds of a percent are made by bicycle.

* Only 1 percent of Canadian commuters report bicycling as their usual mode of transportation.

* The average car produces about five tons of carbon dioxide per year. In the US, cars were the source of about one-third of global warming pollution in 2005.

* If Americans replaced just one in five of their average length car trips by bicycling, each driver would spare the atmosphere more than one ton of carbon dioxide emissions. Collectively, the effect would be comparable to taking 48 million vehicles off the road.

* Short car trips are the easiest to replace with a bike trip. Mile for mile, they are also the most polluting.

* For each mile of new lane, the materials and machinery used to build a highway release between 1,400 and 2,300 tons of greenhouse gases.

* Among major U.S. cities, those with extensive bicycle lanes have three times the rate of bike commuting compared to other cities.

* Bike-friendly policies, from traffic calming to car free downtown zones, have boosted cycling rates in five European nations to 10 percent or more of urban trips; one-fifth of all trips in Danish cities are made by bike, and one-third in Dutch cities.

* It costs as much as twenty times more to support a passenger mile of automobile traffic compared to one of bicycle traffic.

* In the long run, the measures most crucial to getting more people on their feet and on their bikes are those that fight sprawl and encourage dense, livable cities. On average, city dwellers drive a third as much and half as fast as suburbanites.