We need to be asked, to be reminded, and to be thanked.
But if you want a lot of good reviews, don’t hesitate to politely request them. Your fans won’t mind helping out.
Here’s a good example from Dockers, sent by email two weeks after an order. Great opening: “The only thing more important to us than making great khakis is making sure you’re happy with your purchase. Now’s your chance to tell us. So, don’t hold back — good or bad -= we want to hear from you.”