Litespeed road frames don't use replacable hangers but seem strong enough that if you hit something hard enough to damage the hanger, you will damage a lot more anyway.

A couple of years ago, I rode over a piece of steel coat hanger wire that got caught in the chain and sucked through a nearly new Ultegra rear derailleur. It absolutely distroyed the derailleur, bending the cage and the parallelogram into a twisted mess. The derailleur hanger was completely undamaged.