Upon replacing my rear brake pads, I noticed that my rear wheel is not properly centered. The consequence is that the wheel is pressed against one of the brake pads, as can be seen in the pictures below. I have a Rohloff hub where I can pull the dropout+wheel back in order to tighten the chain, but I don't know how to center the wheel horizontally. In the final photograph (number 4) I have marked with A and B the dropout. Normally, I put in the wheel by turning the bicycle upside down and then let the wheel into the dropout, going "all the way". But If i do so, it results in the rim being pushed against the brake asymmetrically. If I slightly raise at A and then close the quick release lever, the wheel is free from the brake, but it is not very stable, I think it's not the normal situation.
The wheel appears centered if I test the distance to the axle when putting it on the floor:
Dropout looks like this:
My question: how do I keep the rear wheel centered in the axle and straight for my bicycle (Rohloff hub with longitudinally movable dropout, Magura HS33 rim brakes)?
It appears the wheel is straight, but it was not centered. I have those pads on both sides, and one side was pulled back much more than the other. I determine this based on the length of the visible part of the thread. I fixed it now, but I think the reason it keeps going bad regularly is because one of the screws is missing:
See the void in the second picture...
I remember that I unsuccessfully hunted for such a screw, but then concluded that it's not essential and continued cycling. But I can't anywhere in this area find a screw with an inbus-head and the right diameter. I used a screw with another head, but couldn't tighten it very well and — as I found out now — it fell out again...