According to this article, what defines a generation ?

"Wheels of Change" tells the story of the impact of the bicycle on women's lives from 1870s to the early years of the 20th century. It tells the stories of women who rode bicycles for fun, for profit, and to make a statement about women's rights or women's roles in the world.  found the answer here:
https://searchworks.stanford.edu/view/10208329