1984 Trek 520: "the Bronze"; '80s Panasonic road bike (innominate); '97 Raleigh Century: "Rubeus" because it's red, and twice as heavy as a normal bike; blue 90's Peugeot Mackenzie :"Bix" (beaterbike), 2007 green Bike Friday New World Tourist.
I suspect their actual function is to centre the wheel in the chainstays.
Yeah I thought that but I didn't know if they were absolutely necessary since I think my wheel is running pretty straight and true without them. I just wanted to know if there was any potential damage in running the bike with the axle tight up against the rear dropout? The dropout has a hanger if that makes any difference.