Perhaps someone can verify my knowledge of lifting history, but I believe that at one time single arm lifts, e.g., the one arm snatch, were actual competition lifts in weightlifting. This is why bars had the center knurling. These lifts are no longer contested so there is no need for the center knurling. I like the center knurling for back squats because it creates extra friction to keep the bar in place, although it's not critical for the high bar position as the bar sits on a "shelf" created by the traps. I would think center knurling is almost a requirement for low bar squats as the "shelf" on which the bar sits is less secure. For front squats and the Olympic lifts themselves I like a bar without the center knurling.I think it's odd that barbells don't come with the center knurling option.
Ooh, you're right, I missed that one, and it seems to be everything I'm looking for. Hmm......@Anna C, skipping through the thread I recall no real consideration of the Ohio Power Bar (https://www.roguefitness.com/rogue-ohio-power-bar-20-kg).
It has center knurl and because I considered buying it myself looked up some reviews on the net and they're all poitive.