I have no idea how good these estimates are, but…
According to Clarke (executive director of the League of American Bicyclists ), Americans who participated in Bike to Work Day last Friday . . .
—saved more than 56 tanker trucks of gasoline
—saved $5.7 million in driving costs
—prevented 4,580 tons of carbon dioxide and 230 tons of carbon monoxide from entering the atmosphere
—burned 410 million calories