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I’ve been using Garmin Varia RTL515 cycling radar for more than two years on my road bike. In this review, I share my experience with it and answer some frequently asked questions like:
- Do you need the Garmin RTL515 Varia radar?
- Will it increase your safety on busy roads?
- How does it work?
- Is it worth it?
- And more.
OR, read my full, in-depth review, where you will learn more about its features, benefits, and how you can benefit from this taillight + radar on your bike.
NOTE: Garmin recently introduced a new Varia RCT715 radar with a camera and taillight. Read my RCT715 review for more info.
Who Is Garmin Varia RTL515 Radar for?
Garmin Varia RTL515 radar with taillight is a useful gadget for all cyclists that ride in traffic. It increases the rider’s traffic awareness and, thus, their safety.
Road cyclists can take the most advantage of this it because it will inform them about approaching cars and other vehicles.
However, you can also use the radar if you commute to and from work on your bike. Remember, you must connect it to your bike computer, Garmin Radar display unit, or your smartphone (via the Varia phone app).
Check my other article on bike phone mounts to use your phone as a head unit.
What’s in the Box?
Before I dive deeper into how the radar works and share my experience with you, let’s see what you will find in the package. It contains:
- Varia RTL515 radar with integrated taillight
- Mounting Kit (rubber pads for various seat tube shapes and rubber bands)
- Charging cable (Micro-USB)
- User manual
The mounting kit is handy because it contains several rubber pads for different shapes of seatposts.
The manufacturer did not forget about the standard, rounded seatposts, as well as ‘D’ and ‘V’ shape seatposts, which can be found, for example, on aero road bikes.
How Does Garmin Radar Work?
Garmin Varia RTL515 is the 3rd generation of radars from Garmin. I first saw it while training with my friend. I was amazed by it.
Unfortunately, he was unable to explain how it works. So, I did the research and found this info on the Garmin website:
Varia Radar Tail Lights have a radio transmitter that emits radar signals behind your bike and a receiver that detects radar signals reflected by moving objects behind you. It analyzes the reflected radar signal to identify vehicles and determine their distance and approach speed.
This means that if a car approaches you from behind, it appears on your cycling computer (or smartphone) and gives you an audible alert.
The Varia radar can detect relative speed. Vehicles approaching a relative speed of more than 55 mph (90 km/h) will be displayed in red, while cars slower than this threshold are displayed in orange. (Source)
The audible alerts also differ for slow and fast-approaching cars.
My One+ Year Experience with Garmin Varia RTL515
I would not say the radar is an essential bike accessory. But it increases my convenience, and I feel much safer. So, if you want an upgrade, I can recommend it.
It is a great tool if you ride on roads with heavy traffic. You will know about every car that approaches you from behind.
Probably the biggest advantage of the Varia Radar for me is when I descend. I often looked behind myself to avoid blocking cars behind me.
Let’s now dive deeper into the features of RTL515, its pros, and its cons.
Garmin Varia RTL515 Main Features
- It detects up to 8 vehicles at a distance of up to 153 yards (140 m).
- The taillight is pretty bright (60 lumens), which means up to 1-mile visibility.
- The radar weighs 71 g (without the mounting kit).
- The battery life is up to 15 hours (day flash mode) and 6 hours (always on mode).
- The radar is connected to a head unit via Bluetooth.
- The taillight offers 4 modes (always on, peloton mode, day flash mode, and night flash mode).
Based on my multi-year of experience with this radar, I would like to highlight the following pros and cons.
Varia RTL515 Pros
- Increased sense of safety
- Battery life
- Peloton mode
Varia RTL515 Cons
- Micro-USB charging cable
- Possible compatibility issues with non-Garmin devices
- Unstable mount system
Varia RTL515 Pros in Detail
Increased Sense of Safety
The biggest advantage of the rearview radar is my increased sense of safety. I divide it into 2 parts.
The first part is that thanks to the radar, I know what’s happening behind me. Sometimes, you can’t hear cars coming from a distance due to the wind noise. The radar shows me approaching vehicles even before I have a chance to hear them.
TIP: You may also be interested in these bicycle safety tips for the 21st century.
I also often tended to look behind me, for example, on downhills. This can be very dangerous – I could crash easily if there is a pothole. But, thanks to the radar, I know if there is a car or not, so I can adapt my riding style.
The second part is visibility. The taillight is very bright (60 lumens), so it is well visible in daylight. It is very difficult to overlook it for drivers (at night, it is almost impossible not to see the flashing light even from a long distance).
If I ride on my road bike with radar, drivers also seem to give me more space when overtaking me. This is great because if the car overtakes you closely, it may result in a crash.
But, this does not mean you should 100% rely on this device. Although it is very reliable, you will get the following warnings during the pairing process.
Garmin claims up to 15 hrs battery life (day flash mode). I am getting around 14 hrs depending on the outside temperature (when it is cold, it’s shorter).
This is plenty enough time for 3 endurance road rides or several shorter ones. But, you can recharge it to 100% within 5 hours (using a computer) or 3 hours (using Garmin approved AC adapter). Still, the iGPSport SR30 lasts longer.
I also noticed no drastic decrease during one year, which is good news. However, I am very curious about it in the long run (2 and more years).
UPDATE: After two years, my Varia RTL515 still lasts around 10 hours (flashing mode).
NOTE: The radar may reduce the battery life of your bike computer.
I haven’t experienced any false alarms yet. And I have ridden more than 3000 miles (almost 5000 km) with the radar already.
Occasionally, the radar detects cars approaching from a sharper angle (from side roads). But they disappear from the screen quickly.
Even if I got a false alarm, I think it would not be such a big deal. Imagine the opposite situation. No alarm when the car is approaching. It could end badly if you rely on the radar 100%.
This being said, the radar is very precise, and you can rely on it.
Peloton mode is useful when riding in a group. The radar automatically detects the presence of bicycles or vehicles behind you within a distance of 100 feet (30 meters) and traveling at a relative speed of under 10 mph (16 km/h).
Thanks to this mode, your head unit will beep when other vehicles approach you or the cyclist behind you at a relative speed that is higher than 11.18 mph (18 km/h).
The taillight will also be automatically dimmed so that it won’t dazzle your friends so much.
Varia RTL515 Cons in Detail
Micro-USB Charging Cable
For me, its biggest disadvantage is the Micro-USB cable and the absence of USB-C. Since many new laptops, chargers, and devices feature USB-C, Micro-USB is a problem.
It is a pity that Garmin did not use the newer standard and did not contribute to its unification. However, we may see USB-C in a future release. We will see.
Compatibility Issues with non-Garmin Devices
The Garmin Varia RTL515 was initially only compatible with Garmin devices before third-party manufacturers rushed with firmware updates and support.
I use Varia RTL515 with a Wahoo ELEMNT ROAM head unit. The only feature that does not seem to work is the automatic turn on and off after connecting (disconnecting) with the Wahoo bike computer. This means I have to turn it on and off manually.
Nowadays, it works with most ANT+ and Bluetooth-compatible bike computers too. But the controllability is limited to Garmin Edge computers.
My experience with the supplied mount was good on my old bike with a rounded seatpost.
However, it’s unstable on my new bike with an aero seatpost, and I have to adjust it often (mainly after sprints, surges out of the saddle, or bumpy descents).
If you have a rounded seat post, you can solve this problem by purchasing a hard mount for the Garmin Varia RTL515.
For aero seatposts, I recommend the KOM Cycling mount:
Garmin Varia RTL515 Alternatives
There are a few Garmin Varia RTL515 alternatives. For a long time, only Garmin produced bike radars. This changed in 2022 when Magene and Bryton introduced their radars.
NOTE: RVR – Rear Varia Radar, RTL – Rear Tail Light
Garmin Varia RCT715
Varia RCT715 is the latest addition to the Varia family. It also includes a camera for recording what’s happening behind you, so you will have footage if somebody endangers you on the roads.
You can check out my comparison of RTL515 vs. RCT715 for more info.
Garmin Varia RVR315
This is a Garmin radar without the taillight. It has a slightly lower battery life.
Magene L508 offers better light modes customizability but has shorter battery life, gives more false positives, and worse multi-object detection. Read my Magene L508 review, where I go in-depth.
Bryton Gardia R300
Bryton Gardia R300 has a sturdier mount and similar battery life but gives more false positives and has worse multi-object detection. You can learn more in my Bryton Gardia R300 review.
Check out this comparison of Garmin Varia RTL515, Magene L508, and Bryton Gardia R300 for more info.
The bike mirror costs a fraction of the price of the Varia radar. Of course, they are not as smart, but they may be an interesting alternative if you are on a budget. Feel free to check this article on the best bike mirrors.
Garmin Varia RTL510
It is the 2nd gen of Garmin Varia radar. It looks identical to RTL515, but there are some differences (read more below).
Magene L508 was introduced in July 2022. It comes with similar specs as RTL515, more light modes, and a smart brake sensing feature.
Additionally, it has a USB-C port, is more affordable, and looks sleeker.
On the other hand, its light is not as bright, its mount lock is looser, and the battery life is shorter.
Bryton Gardia R300
Bryton Gardia R300 should offer better specifications than RTL515. However, it has not been officially launched yet.
Garmin Varia RTL515 vs. RTL510: What’s the Difference?
Garmin RTL515 and RTL510 are identical. They differ in 2 features only:
- Unlike the RTL510, the RTL515 offers Bluetooth connectivity with applications. Thanks to it, you can connect the Varia RTL515, for example, with the Varia application or other applications like RideWithGPS.
- RTL515 battery lasts approx. 1 hour longer than the RTL510 battery, so you don’t have to recharge it as often. However, both devices offer a long enough battery life that lasts long enough throughout your bike ride (unless you ride 15* and more hours).
*Battery life of RTL510 in flashing mode.
Garmin Varia RTL515 FAQ
I honestly have to say that I feel much safer with the Garmin Varia radar. I take it for every road ride, even for group rides. Nobody complained about its brightness (yet).
For me, it was one of the best upgrades for my road bike. It is one of the kinds of devices that you don’t need, but it will make your life easier when you have it.
So, should you get it or not? If you are a roadie that has some money to spend, yes. You won’t regret it.