There is a fallacy among writers than free reads encourage sales of your books. I can tell you it is a LIE, free reads do NOT boost your sales, here are examples to view:-
On this blog Sexual Explosion had over 1,750 reads and not one sale. http://www.amazon.com/dp/B008BK1WDK
On Scib'd chapter one of Chronicles of Mark Johnson has over 350 reads but not a sale. http://www.amazon.com/dp/B008BEDMSO
Old Church Ghosts is my most popular story with 3 versions but although its popularity is not in doubt, there have been no sales.
Many writers will argue the opposite view, I am giving you the view from my point of view – statistics tell their own story, or maybe I am just a bad writer?