Originally Posted by airosen

Not quite. On a bike, you don't actually balance yourself by turning the handlebars - rather, it's about where your weight is. So on rollers (just as on the real road), you maintain balance by shifting your weight. Now I don't want to get into angular velocity and gyroscopic properties and such, but basically your front wheel has to spin for you to be able to control the bike and keep it upright on the rollers.