Originally Posted by Jim from Boston

I use both left and right rearview mirrors, in my case Take-a-Look eyeglass mounted ones. I got the idea from a cycling companion who used only a right hand mirror.

The additional right hand mirror affords a pretty good rearward view, but is particularly useful:

• 1) Riding on the left-hand side of a one-way street
• 2) ... 6)
• 7) When wearing a backpack, usually one mirror has a less-obstructed view over my shoulder.

My main argument for a mirror, particularly in the urban environment is summarized by Jim’s Law of the Road: “No matter how well paved or lightly-traveled the Road, a vehicle is likely to pass you on the left as you encounter an obstacle on the right.”….