You are right the axle is not symmetric and has one longer end where the sprocket mounts. I have that oriented correctly. However now that you mentioned it, I do remember pulling out the ball bearings and noticing that one side had 1 less than the other. I added the extra bearing in good faith but that is probably where the extra space is taken up. Ill try taking one out on the side opposite of the sprocket and tighten everything up to see how much extra I gain.