Originally Posted by
777funk
As far as the dropout spreading... the road bike in question has built in frame tension pulling the dropouts out and away from being pressed tight to the bike hub. If the small diameter skewer bolt were to snap and fall out, clamping force would be gone and the dropout would spread (tension pulling its two sides outward). The axle (8mm diameter) that touches the frame, only does so by say 1/4" axle length or so on either side of the hub. Of course this takes the load when all is intact and everything is good. Once the frame were to spread open (in the case of clamping force from the skewer being gone), the dropouts would spread to clear the 8mm axle and the wheel would be free of the frame.
It sounds like you're using the wrong width hub for your frame. Dropout spacing on the frame should
match the over-the-locknuts (OLD) width of the hub. If your axle is long enough (you only need a millimeter or so projecting past the locknut on each side), you could add spacers under the locknuts to get the OLD to match that of your frame.
And 8mm sounds undersize for a rear axle. 10mm is typical, and even wider diameter axles can be found on tandems and other high-load applications. What kind of bike is this, anyway?