I have used bar end mirrors, ones that strap to the hoods and finally settled on the "Take A Look" mirror that mounts to my helmet. It gives me better coverage and allows me to scan back and forth behind me. You can bend the three prongs that create a friction Mount on your helmet for a more secure mount. It stays on great for me.
The bar end mirrors work, but I found road vibrations being transferred to the mirror.
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F Thomas
"Life is like riding a bicycle. To keep your balance, you must keep moving."
Albert Einstein (1879-1955)