I agree with DaveB and use a bar end mirror for all rides. I have been using one for over 30 years and would not ride around the block without it. I disagree with Russ. I think the mirror can save your life. I can ride safely, watch the road and the mirror. A mirror allows you to actually have some control over the situation when riding. After a while, you can get an intuition about what a car is going to do, whether they are erratic or not, etc. A mirror often can tell you when it's best to "take the lane" or even leave the road. I've done both. Another thing you can do if you sense a car is not taking you seriously is do a little swerve into the road. This often makes the car driver wake up. You can see and hear them slow down and work to go around you. It takes a lot of riding to really get a sense of how to effectively use a mirror. Without one, you're helpless and completely at the mercy of whatever is coming. I've discussed this with scores of riders. Those that do not use a mirror always say they don't use one because there's nothing you can do if a car is going to hit you. This is a fatalistic and wrong view, in my experience. I want to control the situation, and a mirror gives me way more control. On the Pacific Coast ride, this is esp important, because there are parts of HWY 1 in Calif with no shoulder, narrow and curvy roads. And oblivious, often elderly drivers, sometimes driving wide RV's. I'd get a mirror and start practicing.