When I was a kid, just big enough to ride a 26" bike with wood blocks on the pedals, my dad brought 3 bikes home from the junk yard or something -junk bikes. 2 were probably CWC and 1 was a Schwinn. I learned then and why I favored the Schwinn. On the CWC drop-outs, they were thinner and softer steel. ya gotta set the axel adjusters just right and without a thick and hard washer; As you squeeze it tight the nut can bend in the washer, spread the drop-out and push the axel out of adjustment. I can't remember if I ever solved that where it didn't need constant adjusting. Yet cheap 50-60's Murry and huffy with forward drop outs would spread easy too. Had to hammer them back which caused the metal to become weaker. Schwinn lock washers are harder and thick so, usually will not become depressed and spread the drop-out again. They can bite the steel and help. As I have not played with this problem in many, many years , others may know a better solution but for me these worked:
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