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

Garmin Varia review: RTL515 radar mounted on my road bike

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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.

NOTE: Garmin recently introduced a new Varia RCT715 radar with a camera and taillight. Read my RCT715 review for more info.


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 their safety.

Road cyclists can take the most advantage of this radar 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 head unit, Garmin Radar display unit, or your smartphone.

Also available at rei.com, performancebike.com, and trekbikes.com

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 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) while 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 rei.com, performancebike.com, and trekbikes.com


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.

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 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 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, and 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 happening 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 – 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).

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

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 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). UPDATE: My Varia RTL515 still lasts more than 10 hours (flashing mode).

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

Reliability

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 rei.com, performancebike.com, and trekbikes.com

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

My experience with the supplied mount was good on my old bike with a rounded seat tube.

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 use a rounded seat tube, 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

Unfortunately, I haven’t found a solution for my aero seatpost yet.


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.

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Garmin Varia RCT715

Garmin Varia RVR315

This is a Garmin radar without the taillight. It has 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).

Magene L508

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.

Magene L508 in my hand.
Magene L508

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:

  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.

Also available at rei.com, performancebike.com, and trekbikes.com


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 rei.com, performancebike.com, and trekbikes.com

About The Author

10 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?

  3. Thanks for the great, real world review. I just got mine, hooked it up this evening and will test it on my morning commute, I can’t wait!

    Happy riding!

  4. Hello,
    I wrote to the My Bike Traffic website with the following Qs:

    I have an Edge 1030+ and 520+.
    I’ve noticed they are both picking up vehicles perpendicular (at least very close) as far as 5 lanes (100 ft or so) away. Does the fit file also contain sufficient info to tell how far to the left (in the USA) the auto is? If so, can this be added to the info for the rides?
    Which brings the other question, what are the data fields for the Fit file?
    Have you been approached by Strava, Google, Apple, Garmin, etc., to farm out this info? It seems to me this would be very valuable info for some of these sites as they are starting to beef up the biking info, and the data could provide basically live radar speed info for stretches of road (the DOTs may like this info as well and of course the cops). This could be correlated to accident and injury events and provide the most dangerous stretches of the road etc. (as well as safer, I think it was Outside that was tracking bike vehicles collisions and deaths). If the Fit file can determine how far to the left or right a car is, 3 feet is the law here (NV). This may also be informative. Some reviews of the Varia kinda poo poo it, but if the data can be expanded and become integrated into websites, that alone makes getting a radar unit valuable in and of itself.

    So I have a 715 and like it as it does up the safety feeling… But I think the overall data is maybe of even more value and provide sufficient value for everyone to have a radar unit.

    1. Hi Jon,
      I am afraid the fit file doesn’t include the details you refer to. However, the things you propose would be very interesting! We will see if Garmin (eventually other manufacturers) will try to implement them.
      – Petr

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