[SequoiaHope]

To anyone who wants to ride more safely I cannot recommend enough this simple $20 mirror which I find so valuable that I buy extra and hand them out to friends and strangers to help keep them safer. A mirror mounted on your glasses or a similar mirror affixed to your helmet (close to your eyes and mounted on your head) allows for a large field of view that you can easily steer to see behind you.

I ride on the streets of Oakland every single day and situational awareness is critical. The single biggest thing you can do for safety is watch each car as it approaches behind you for its speed and trajectory. Anyone approaching too close or too fast is a bad sign and with a mirror you can more easily avoid them.

These are also available on Amazon and I am not in any way affiliated I just think they’re good life saving technology:

https://takealookactive.com/

[laluser]

Obviously the mirror gets the job done, but I use Garmin Varia radar hooked up to my bike computer and you can see cars behind you and their velocity is displayed as different colors. It’s way more expensive, but amazing for road biking.

[EsotericAlgo]

I’ll second this, it’s absolutely a game changer. I’ve used handlebar mounted mirrors and the like but I’ll never willingly go back.

I tend to prefer helmet mounted and I glue them on which isn’t my favorite thing to do on a new helmet. It’s also a bit frustrating when you find yourself cycling in a country that drives on the opposite side.

I do find that on very long tours the week following I’m looking where I’d expect the mirror to be when I want to look behind me.

[bboozzoo]

This looks like a choice is a serious eye injury if you roll is something you're looking for. Why not buy a handlebar mirror like this one https://cateye.com/intl/products/accessories/BM-45/ I have one on each of my bikes, road/gavel/fitness. Dirt cheap, gives very good rear visibility and very compact size.

[SequoiaHope]

Handlebar mirrors won’t give you as much field of view and you can’t steer them with your head.

[belZaah]

Radars do this better. They can warn you from much further away and do not require for you to keep an eye out - there’s audible cues.

[SequoiaHope]

Do they also show bikes? I use the mirror not just to monitor cars but see where my friends are. If a friend breaks down and is on the side of the road I want to see without having to fully turn my head around.