Top positive review
One of the best items I've ever bought for my bike
Reviewed in the United States on September 4, 2018
Hands down, this tail light has been one of the best products I've ever bought for my bike. I tend to be a bit skeptical of products and I had my reservations at first, but after reading some reviews and watching a few videos it seemed to be a great fit for the type of riding that I do. I generally ride alone on rural roads and having the ability to know if someone is coming up behind me has been a great asset.
The unit is charged with a USB cable with one power button to select between several blinking modes. I suppose it can be used as a standalone tail light, but that defeats the main benefit, which is radar. I use an Edge 810 and after a software update of my headunit, the tail light paired up without issue. There are settings in the headunit that can change the blink pattern of the light when a car is detected as well.
Once the light is paired with your headunit, the screen will display the data like normal but will have an additional symbol in the upper right corner. When a car is detected, the unit will give an audible beep, and a red bar will show up on the left and right side of the display with a small dot that represents a car, if the unit detects two cars, two dots will show and so on. If the closing speed of the car is quick, the dot will move rapidly from the bottom of the screen to the top. Once the car passes, the display will change from two red bars to two green bars.
If you do Strava segments, you probably know the display on the headunit will change from your "home screen" to the segment and if the RTL510 detects a car, the same red bar/dot will overlay on the segment. So you will always know if a car is approaching you.
I've found the light will detect a car with enough distance and advance warning to allow you to maneuver as needed. It's accuracy has been 100%. The RTL510 will detect motorcycles as well.
Pacelines - During a recent event which occured on a closed track, I was in a paceline and the riders behind me were not picked up on radar. However, I did notice that if a faster rider was coming around us, it would pick them up on radar.
The tail light comes with a single quarter turn mount for use with either a round or aero seat post. I have an aero seat post and the fit is terrific. I'm a big fan of Garmin mounts and I purchased an additional mount for my other bike, it makes it so easy to switch between bikes.
This tail light is bright even in daytime and with the various strobe patterns and burst modes, I don't see how you can't be seen. It's a premium tail light, so it should be expected to be bright.
As far as I know, this light is only compatible with Garmin devices (a full list is available from Garmin's website). Buying this taillight is making a pretty large investment into the brand and Garmin headunits have caused frustrations with users in the past (myself included), so do your homework on the headunits before buying this tail light. - EDIT 8/28/19 - Wahoo announced support for ANT+ and RADAR on 8/27/19, there are several youtube videos showing the operation of the RTL510 with the Wahoo head units. This is a great addition for Wahoo users.
As a tail light it's impressive, but not a standout, having the radar capability makes it standout from the crowd. It's one of those things that after taking a few rides with it, I find I don't want to ride without it. If you're already a Garmin user with a compatible device, it's terrific. If you're just getting started or thinking about switching from another platform, I'd make sure Garmin is where you want to go before buying the RTL510. To use an analogy, Garmin headunits are like a sundae, the RTL510 is like the cherry on top. EDIT 8/28/19 - no need to debate platforms (Wahoo/Garmin) anymore!