Varia RearVue 820

There are a few questions I have:

-will it fit old mounts? It’s provided with a new one. 
-will it be possible to disable flashing on the international model like with the 515? I don’t want to buy a STVzO (german) version so I would import one, but I would like to be able to make it compliant if I wish. 

You know what's annoying?  I've been struggling with an old Varia whose battery was showing signs of age, and wouldn't survive longer rides anymore.  I could feel it in my waters that a new model was coming about a year ago.  Just before a cycling event last October, I couldn't wait any longer, and bit the bullet and bought a new one.  If only I waited 3 more months...

Also like this:

Mixed feelings from me.  I like the brighter light, braking function and larger battery.  However, the cost is too much and I don’t think the extra information it provides is useable.  To be useful I would need to be staring at the head unit for longer than is safe.  If Garmin brought out a revised heads up unit that shows the information in your glasses it would make the information valuable.

The brake light function is the least interesting for me because I have owned several taillights with that feature and none of them work the way one think they should. I assume brake light function on the RearVue 820 uses accelerometer like others. My experience is that the brake light does not turned on unless there's a rapid deceleration so most of the time, tapping the brake to slow down does not trigger it. Occasionally, hitting a bump or pothole also causes the brake light to engage. On top of that, because there is no standardized implementation of brake light on bicycle taillights, the person riding/driving behind you most likely won't have a clue the significance of it when brake light ever gets triggered.

Good point and very true.

“In addition to haptic alerts on your wrist, selected Garmin smartwatches can also give voice alerts for approaching vehicles.”

But I really hope the user can select between a voice or just still a beep.

"A 7-ton truck is approaching you at 80 km/h. A normal-sized car is approaching you at 100 km/h...."

Does this thing constantly chatter away on a busy street?

Let me share my experience today. We were riding in a group. I had the radar set to not light up and switch to radar threat mode (warning flashing) when an object was detected. If I was the last one, everything was fine and the Garmin behaved as expected. The problem occurred when someone in the group got behind me. The radar detected him and switched to radar threat mode and flashed at my fellow cyclist as if there was an approaching object the entire time. It is obvious that the radar threat mode is useless in a group, because the radar, unlike the 515, also warns of objects traveling at the same speed. So I turned off the radar threat mode to relieve my colleagues riding behind me. Unfortunately, I did not relieve myself, because I still had a radar bar on the screen, warning me of the colleague behind me. And that bar was there for the next two hours of our ride. My colleague is used to riding at the end of the group and the bar on my screen did not bother him. I guess I should have left the radar threat on after all :-) So I bought an expensive device, the benefit of which is that it made the screen of another, even more expensive device (Garmin 1050) smaller. I also wanted to try a user-defined flashing mode. I created it and named it using the Varia app. What was my surprise when I couldn't find this mode in the corresponding widget for controlling the light network. So you can create your own mode, but you can't start it from the Garmin on the handlebars, you have to stop and set it using the remote on the radar. So to sum it up, I'm going to return the Garmin Varia Rearvue 820 radar to the dealer next week.

I reported this issue with Garmin support today, it is a dumpster fire when riding in a group, I had a cyclist warning for 95% of my ride, so like you the overlay was always on my computer, Garmin need to fix this, it is amazing to me that this made it through testing