I cut a tiny little slot in one tooth on my chainring and on my sprocket. And with enough dirt I could not see that slot any more, so later put some yellow paint on that tooth on one side. I always put an outer plate link on the tooth with a slot or yellow paint.
My chainline is slightly off, my bottom bracket spindle should probably be 10mm longer for ideal chainline. But I wanted my pedal width (or Q Factor) narrower, thus I chose the narrower spindle.
Remember, most of my distance is ridden on derailleur bikes, so my Rohloff chain and sprocket does not get as much wear as most of you probably get on your bikes. I am still on my first sprocket.
Photos are five years old, so I am sure I have a lot more wear now, I took these photos before I flipped the sprocket.
When you look at the first photo, the side of the sprocket you are looking at was on the outside, thus the chain pulled towards the right on top of the sproket. It is quite evident that the links with inner plates were on the teeth that have more side tooth wear, the inner plates rubbed on the teeth as the chain engaged and later unengaged the sprocket. The second photo is the inner side of the sprocket, because my chainline was slightly off, the second photo shows less wear on the inside side of the sprocket.
When you look at the teeth in either photo, they both appear to be quite worn with that shark fin shape, and if you only look at the teeth you can't really see which teeth are worn the most. But, keep in mind that when that sprocket was new, the hole under each tooth was centered under that tooth.
Now if you look at the position of the tooth over that hole in the first photo, both teeth appear to be shifted a bit to the right of that hole but the tooth that had inner plate wear is shifted even further to the right of the hole below it than the notched tooth. Actually the teeth did not get shifted to the right, a bunch of the metal on the left side of each tooth is now gone, which is why the teeth are no longer centered over the holes.
So, I think what is happening here is the chain and teeth wore in together, since every other chain link was slightly longer, now that means that the sprocket teeth have worn to match that chain wear. So, every other tooth is worn a bit more. Thus, I think that each tooth now was engaging each roller on the chain evenly.
But if I had a worn chain where every other link was longer, and if I had a sprocket with odd number of teeth, only every other chain roller would be pulling on every other tooth because the teeth would have worn evenly when the chain did not wear evenly.
Immediately after I took the photos, the sprocket was flipped. So, after the photos were taken, the sides of the teeth that had no wear before started wearing every other tooth more to match the worn chain. For the last several years I have stopped putting new chains on my Rohloff bike, instead I only put chains on it that are already at 0.75 elongation from use on one of my derailleur bikes. So, I am consistently putting worn chains on worn teeth.
Yeah, I am sure I sound quite obsessive on this. That was not my intent. I am just trying to be quite complete with my thinking on this matter.
I have an eight speed drive train on my randoneuring (or audax) bike, light touring bike (titanium frame), medium touring bike (Thorn Sherpa), my folding bike (Airnimal Joey). And a seven speed drive train on my errand bike. So, I wear out a lot of derailleur chains that will fit on my Rohloff bike. My road bike has a 10 speed drive train, but I have not yet worn out any chains on it, it is my newest bike.
