mirrors
What Emily said! I agree totally! I got one of the Take-a-Look mirrors years and years ago because a mirror was a requirement on a ride I was going on. I thought I would hate it, having once tried the round third eye mirror and getting literally dizzy on the bike trying to use it. Anyway, I got the larger of the two sizes of take-a-look rectangular mirrors and I couldn't care less about the "geek" factor because I love this mirror. I ALWAYS can see what's behind me. Maybe that's why busy roads are not too scary. I don't like them, but I can handle them. There have been times I've moved over onto the shoulder when I could tell a truck wasn't going to give me as much room as I'd like. I really feel the mirror saved me from getting hit at least twice in the past 5 years. For that alone, it's worth it.
I don't wear the mirror when racing (not that I race all that much) because I don't think it's legal. Don't know for sure, but I've never seen anyone else with one on, so figured I better not. I also don't wear it while riding off-road. Too many branches to hook on. I miss it when I don't have it on! For all training rides and all fun rides, that mirror is always on my sunglasses. The mirror also has an adapter for helmet use, if you prefer to do it that way. Make sure you get the bigger of the two models if you want to put it on a helmet. The small one doesn't have the adapter. And be careful how you position it. It's a little tricky to do. Maybe even have the shop where you get it put it on for you and try it out to make sure you can see behind you well.
I know there are some people who try mirrors and just don't like them. I'd be curious to hear reasons why, if there's anyone reading this who feels that way. Always good to hear both sides.
Time is a companion that goes with us on a journey. It reminds us to cherish each moment, because it will never come again. What we leave behind is not as important as how we have lived." Captain Jean Luc Picard