Originally Posted by BostonFixed
All of the older frames didn't have replacable derailleur hangers.
On an older steel frame road frame I have, the rear derailleur found it's way into the spokes due to my carelessness, bending the derailleur hanger, but the derailleur was perfectly fine. I did re-align the derailleur hanger/dropout with a 5 pound sledge hammer.
Well exactly. But with aluminum or carbon you can't (or shouldn't) be bending the hanger back. Hence the popularity of replacable hangers, as found on many of these bikes.