Why are London cyclists so white, male and middle-class?

A fascinating study of why some Londoners cycle and others don't illuminates cultural obstacles Boris Johnson's cycling plans must overcome

Among the several good objectives of Boris Johnson's Vision for Cycling in London, produced in 2013, is an increase in the variety of Londoners who travel by bicycle. As Johnson himself puts it on page 5:

I want more women cycling, more older people cycling, more black and minority ethnic Londoners cycling, more cyclists of all social backgrounds - without which truly mass participation can never come.