I find it much safer to ride not in the middle of the lane, but on the left of the lane (as long as you are going the limit or it is a road with 2 lanes in one direction). the middle of the lane is the grease track. Think of where all the grease and shit drips off of cars. So you want that under your wheels? If you hold your lane you may get people pissed, but it forces asshole drivers to use the other lane to pass you. Ride safe, be aggressive.