Originally Posted by
KCtheK
When I coast downhill without pedaling, the chain comes off the front ring. Obviously this can be dangerous.
Your freehub isn't freehubbing. When you pedal, the top span of chain tightens and drives the rear wheel. When you coast, that span goes slack. When your freehub iis bound by friction, it pushes the chain forward, causing ti to derail from the chainring. Your hub needs adjustment or a complete overhaul. I suggest you don't try to do it yourself.