A new US study has concluded that if just half of all car journeys under 4km were done by bike instead, the economic benefit for a population of 31 million would be $7Bn.
http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info:doi/10.1289/ehp.1103440
http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info:doi/10.1289/ehp.1103440