Michael G.wrote a review of Garmin Varia Rearview Radar Light Bundle on June 22, 2018
Familiarity: I've put it through the wringer
OK, I love this device. I often ride on busy stretches of road with traffic speeds of 55-65 MPH and this is like a second set of eyes.
First, it detects cars approaching from behind but only shows them if they are moving faster than you are. This great because it 1. doesn't draw your attention to non-threats and 2. drops tracking if a car slows down to turn or stops.
Second, it has wide range, for me, it detects at least three lanes wide (I know this because I get tracks for the turn lane (left or right) and the straight lane. So, if I am in the center lane passing a left or right turn lane, it shows tracks in all three lanes, Now, the display is not robust enough to show three different lanes (only a single indicator on the display) but it makes one very aware of all potential traffic threats.
Third, the cockpit display is really pretty small (smaller than I expected) so I was pleasantly surprised. I have it mounted right next to my computer and it really tucks in nicely. Even though it is smaller than I thought it would be, it is big enough and it is easy to see.
Fourth, the tail light changes brightness and flash speed as cars get closer. Now, this may seem insignificant on the surface but the cars approaching from behind pass me at a slower speed and give me a wider berth than normal prior to adding the device. Any roadie will tell you that there is nothing insignificant about that.
Fifth, the devices mount to the included brackets with a quarter-turn lock, very solid and very secure.
Sixth (and finally), when I powered off the display it also powered off the taillight. An added and unexpected bonus.
Ok, only one negative comment, the display uses white light to indicate a car is approaching from behind. To the left of the indicator are two other lights that are also white. I would like it better if the only white light was for an approaching car.
And one "I wish" comment: I wish the kit had contained a rigid (not held on with rubber-bands) handlebar mount along with the included seat-post mount.
Closing thoughts: I ride almost exclusively solo and put this in the must have category, it really is like having an extra set of eyes and while it does not call out a "car back" warning, it does give you a lot of information with a quick glance including how many, how far back (up to 450 feet on a straight stretch) and an indication of how fast the car is approaching. At highway speeds (55-60 mph), with a closing speed of about 35 mph, I gained an average of seven seconds of warning that a car was approaching, better than my little mirror provided. If you are even thinking about buying this do it.
Update 23JUN18: Used it today on an organized ride and found myself riding in a group a couple of times. It allowed me to see how it worked around other cyclist...It does not detect other cyclist (individuals or groups) good if you are a group-rider, not so good if you want to know if another cyclist is approaching from behind. Also, it does pick up trains (makes sense), tracks are about 25 meters off the road...this does prevent the unit from displaying cars while the train is present.