I wouldn't ride without my rear view mirror. I have a bike where nothing is standard, so I had to shop high and low for a mirror that would fit on the handlebar. And of all places, I found it at the hardware store (Canadian Tire for those of you in Canada), and it was 5$. I loved it so much that when I rented a bike that was not outfited with a mirror, I bought another one. Sometimes, we go for the specialized stores, when the thing we are looking for might be right in our backyard. But, yes, the rear view mirror is a must. Specially in the city.