Mirrycle mirrors are good and are inexpensive. Just keep them adjusted.
https://www.amazon.com/Mirrycle-FBA_MI3002-2-Mountain-Bike-Mirror/dp/B000BR4NIC/
Be sure to use a mirror that will rotate out of the way without moving the handlebar if it is clipped by a car's rear view mirror as the car passes. A rigidly mounted mirror can kill you. You can adjust the tightness of the Mirrycle mirror so it rotates easily out of the way if hit.
I don't understand why bike mirrors are not more popular with non-racers. A tiny amount of weight, a tiny amount of air resistance, and a mirror can save your life. Talk about no-brainers!
Only the paranoid survive.
Mirrycle mirrors are good and are inexpensive.
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Used to ride my bike 10 miles to work (one way) and probably did that for 20 years, more than 75 times a year. I had a few close calls... one with a city bus. I called up the municipality and complained and got a call back half an hour later from the supervisor who said he just checked the onboard bus cameras and said he was “absolutely horrified” at what he saw. I asked what happens next and he said “action will be taken”.
Of all the mirrors I’ve used, I highly recommend the ones that clip on to one’s glasses.... you end up with a much bigger field of vision, you can tip your head a few degrees to get an even larger range and you can do all that with a quick glance to the side. I highly recommend them...
https://www.rei.com/product/752285/bike-peddler-take-a-look-mirror
I couldn’t find the one I use but it’s like this...