Originally Posted by
JohnDThompson
Schwinn modified the Huret dropouts on their Sports Tourer frames to accept Shimano derailleurs by cutting a notch in the front of the hanger to hold the derailleur's pivot spring stop.
Unmodified:
Modified:
Or, if you don't mind repainting, you can build up brass on the bottom of the hanger and file a stop for a Campagnolo-type derailleur:
Schwinn notched that dropout to hold a tab from an adapter washer so they could use a Suntour GTV derailleur. See here:
The adapter in question is part number 14. You can see the original thread
here.