Originally Posted by ridelugs
ok lets think about this: if a crank arm was supported on only 1/10th of its internal surface area, would you expect that crank arm to fail or not? the stress is concentrated rather than spread out. its simple. a vertical dropout wraps around 50 percent of the axel, spreading force around.
Indeed, please let's do think about this. The axle is not supported by its tiny area of contact with the dropout, regardless of whether that point of contact is curved or straight. The axle is supported (in its full circumference) by the locknut which is held against the dropout by the opposing nut on the quick release. Those two nuts, with knurled surfaces, pinch and hold the dropout. The threaded-on locknut on the inside of the dropout is what holds the axle in place. The quick release just holds that locknut against the dropout and won't let it move. The support of the axle has nothing to do with how much of the dropout "wraps around" the axle. Nothing to do with it. And most certainly, the shape of the dropout has nothing whatsoever to do with axle breakage.
Originally Posted by ridelugs
snugs the rear axel against the frame, wrapping as much of the axel as a vertical drop out.
Irrelevant.