I tried deadlifting today with the regular sized bar. It wasn't that it was harder to grip, it wasn't. It was just that it hurt my hands a lot more than the thicker bar. I think I know what it is. WIth the smaller bars the bar hits right where my fingers crease. All the weight from the bar is rested on that little crease and it feels like my skin is going to fall off. With the thicker bar the weight of the bar is settled more evently on the fleshy part of my finger and above the creased area.