Originally Posted by
seedsbelize
Huh?
It's called a sprag unit, or one way clutch. It freewheels one way, and engages when you pedal, so basically pushing a bike backwwrds, the drivetrain pulls aganst the clutch(which is a set of flat spotted roller bearings, or pawls) and engages it. Almost all freewheeling bikes do it. I'd be more worried about the same result forewards.