One of the best things I’ve added to my bike gear collection (in addition to some great bikes) is a Garmin Varia radar.
I’ve never been that successful riding with mirrors. When I’ve tried to use them on my bar ends, they just seem to vibrate too much for me to see approaching traffic clearly. If I watch the mirror intently, I’m not looking ahead at the road, which is a recipe for disaster car or no.
The Varia allows me to focus on the road ahead while knowing when a vehicle is approaching from behind. I’ll still try take a peek behind me to ascertain what is going on, but if I’m going really fast or the road is sketchy, I’ll just assume there is a car coming up on me and I need to be careful.
It works great even when you are riding with other people. It will pick up riders that are approaching you quickly from behind but it doesn’t see things that are moving at your same speed, which is generally true for a group of riders.
The user experience is good. When a car comes, my bike computer beeps and shows a dot on side of the display moving up towards the top at a rate relative to the speed at which the vehicle is approaching. If they are approaching very quickly, the alert is more urgent. It also will show multiple vehicles so you know if you are going to be passed by more than one vehicle.
For $99, this is truly a game changer. If you ride, and don’t have one, you should strongly consider it.