Originally Posted by
dddd
I believe that a single axle stop is always put on the driveside because of the chain tension being applied there, otherwise it would make more sense to perhaps use a single axle stop on the non-drive side, since the driveside axle would end up in the right spot as the wheel was centered.
On frames lacking an integral derailleur hanger on the dropout, the bolt-on "claw" acts as the spacer, and the non-drive side slot would have a spacer to help ensure proper wheel position.