I've always had a hard time understanding the influence of the QR on a hub. The QR presses down on the frame dropouts which press down on the locknuts, which are threaded onto the axle and won't move.

How exactly does a QR tighten up the locknuts, when they're literally locked to the cones on the threaded axle? And how is that different from a set of track nuts putting the same or more pressure on the dropouts?

And if it does have an influence, why do all the road hubs I feel not have any extra play in them at all, even though they all come with QR?