Garmin Varia RTL515 Radar Review: Is it Worth Your Money?

Garmin Varia review: RTL515 radar mounted on my road bike

CyclistsHub is supported by its readers. If you buy products using our links, we may receive a commission (learn more).

I’ve been using Garmin Varia RTL515 cycling radar for more than a year on my road bike. In this review, I share my experience 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.

If you are not sure whether to buy it or not, my short answer is YES, go for it. Feel free to buy it right now

OR, read my full, in-depth review where you find out more about its features, the benefits it brings, and how you can benefit from having this taillight + radar on your bike.

Garmin Varia RTL515 Radar – Who Is it 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 his or her safety.

Road cyclists can take the most advantage of this radar because it will inform them about approaching cars and other vehicles.

However, if you commute to and from work on your bike, you can use the radar as well. Just remember, you have to connect it to your head unit, Garmin Radar display unit, or your smartphone.

Also available at,,, and

To use your phone as a head unit, check my other article on bike phone mounts.

What’s in the Box?

Before I dive deeper into how the radar works and share with you my experience, 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
What's in the box of Garmin Varia RTL515 (radar, rubber pads, charging cable, manual, etc.)
What is in the Garmin Varia RTL515 package?

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 Garmin Radar (RTL510) when I was training with my friend. I was amazed by it.

I asked my friend does it work. Unfortunately, he was unable to answer me. 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 head unit (or smartphone).

An illustration of an approaching car on my Wahoo ROAD computer (orange line)
“Slow” approaching car shown in the orange line
garmin varia red
“Fast” approaching car is shown in the red line

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).

Also available at,,, and

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 look for an upgrade to your bike, 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.

Garmin Varia RTL515 attached to YOELEO R12 seatpost
Garmin Varia RTL515 on my YOELEO R12 road bike

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 once 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 (flashing mode) and up to 6 hours (always on mode).
  • The radar is connected with a head unit via Bluetooth.
  • The taillight offers 4 modes (always on, peloton mode, flashing mode, night flashing mode).

Based on my one-plus 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
  • Reliability
  • 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 Garmin Varia 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 going on behind me. Sometimes, you can’t hear cars coming from a distance due to the strong wind. 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 – if there would be a pothole, I could crash easily. 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).

Garmin Varia RTL515 in my hand with a nature background
Garmin Varia RTL515 radar + taillight

If I ride on my road bike with radar, it also seems that drivers 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 Varia Warning on my Wahoo ROAM bicycle computer
Garmin Varia Warning
Garmin Varia Warning on my Wahoo ROAM bicycle computer
Garmin Varia Warning

Battery Life

Garmin claims up to 15 hrs battery life (flashing mode). I am getting around 14 hrs depending on the outside temperature (when it is cold, the battery life is 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).

I also did not notice any drastic battery life decrease during the one-year period, which is good news. I am very curious about the battery life in the long run (2 and more years).

NOTE: The radar may reduce the battery life of your head unit.


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

Peloton mode is useful when riding in a group. The radar automatically detects if another bicycle or a vehicle is behind you at a distance of fewer than 100 ft (30 m) at a relative speed of less than 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.

Also available at,,, and

Varia RTL515 Cons in Detail

Micro-USB Charging Cable

For me, the biggest disadvantage of Garmin radar 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 head unit. This means I have to turn it on and off manually.

I could not test the radar with other brands’ devices, but based on my friend’s experiences, the radar works seamlessly with Garmin devices.

Unstable Mount System

My experience with the rubber pads and rubber bands that hold the Garmin mount is good. It doesn’t happen to me that the radar shifts too much. However, when I ride on roads with potholes and rough surfaces, the radar shift due to vibrations and shocks.

It is very easy to re-align it. But, you can solve this problem by purchasing a hard mount for the Garmin Varia RTL515.

Detail of Garmin Varia with a hard mount on Specialized Tarmac SL6 seatpost
Detail of Garmin Varia with a hard mount

Garmin Varia RTL515 Alternatives

There are also a few Garmin Varia RTL515 alternatives. And we don’t have to go too far away because they are all from Garmin.

NOTE: RVR – Rear Varia Radar, RTL – Rear Tail Light

Garmin Varia RVR315

This is a Garmin radar without the taillight. It has a slightly lower battery life.

Garmin Varia RVR315 radar (without LED)
Garmin Varia RVR315

Bike Mirror

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).

Garmin Varia RTL515 vs. RTL510 – What’s the Difference?

Garmin RTL515 and RTL510 are identical. They differ in 2 features only:

  1. 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.
  2. 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

My Verdict

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 unnecessary 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.

But if your budget is tight and you have other things to buy – like road cycling shoes or a road bike helmet – think twice about your priorities.

Also available at,,, and

About The Author

6 thoughts on “Garmin Varia RTL515 Radar Review: Is it Worth Your Money?”

    1. Hi Sandra,
      good question. I would say it is more convenient and sophisticated. You get a beep sound from your bike computer when a car approaches. The radar has also an in-build LED so you are more visible than without it. Yes, a bike mirror is much cheaper but for me, the radar is worth the price. 🙂

      – Petr

  1. You posed a question about what the battery life will be like after a couple of years of use. I have had the RTL-510 since Nov 2018 and the battery life is down to about 8 to 9 hours, way less if I ride on a street(s) with lots of traffic and the radar is going off a lot. I ride 10 to 15 hours a week so sometimes I have to charge it twice a week. Always ride in flash mode too. Today my Garmin 530 showed the battery had 3 bars out of 5 when I left for a ride, light and radar died half way through a 50 miler. Felt kind of lost without it.

  2. Is it possible to hook it up to a hub generator so that it is always on and does not have to be charged from an external source?

Leave a Comment

Your email address will not be published.

Scroll to Top