Garmin Varia RTL515 Radar Review: Is It Still Worth It in 2025?

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My Varia RTL515 rating at a glance:
Reliability 5/5 | Multi-object Detection 5/5 | Battery Life 4/5 | Brightness 5/5 | Side Visibility 5/5 | Mount 3/5 | App 4/5 | Price 3/5 | WEIGHTED OVERALL SCORE 4.3/5
More about this cycling radar scoring.

Who Is Garmin Varia RTL515 Radar for?

Garmin Varia RTL515 radar with taillight is a useful gadget for all cyclists who ride in traffic. It increases the rider’s traffic awareness and, thus, their safety.

Road cyclists can take the most advantage of this 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).

Also available at rei.com, performancebike.com, and tredz.co.uk

What’s in the Box?

The mounting kit is handy because it contains several rubber pads for different seatpost shapes. 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 third generation of Garmin radars. I first saw it while training with my friend and 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 will appear on your cycling computer (or smartphone) and give 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.

Also available at rei.com, performancebike.com, and tredz.co.uk

My Several Years of Experience with Garmin Varia RTL515

I wouldn’t say the radar is an essential bike accessory, but it does increase my convenience and make me feel much safer. Once you get used to it, you probably won’t like riding without 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.

I appreciate the radar the most on the descents and crosswinds. I often looked behind me to avoid blocking the cars behind me. I no longer have to do that, and I can now choose a safer path. If the radar detects a vehicle, I will let them go if the conditions permit.

Let’s now dive deeper into the features, pros, and cons of RTL515.

Based on my multi-year experience with this radar, I highlight the following pros and cons.

Varia RTL515 Pros in Detail

Increased Sense of Safety

The biggest advantage of the rearview radar is the increased sense of safety it provides. I divide it into two parts.

The first part is that 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.

I also often tended to look behind me, for example, on downhills. This can be very dangerous. I could crash easily if there were a pothole. However, thanks to the radar, I know if there is a car or not, so I can adjust my riding style accordingly.

TIP: You may also be interested in these bicycle safety tips for the 21st century.

The second part is visibility. The taillight is very bright (60 lumens), making it highly visible in daylight. It’s one of the brightest radars on the market, making it very difficult for drivers to overlook. At night, it is almost impossible not to see the flashing light even from a long distance. Furthermore, Varia also increases side visibility, which is helpful at night. The following image compares the brightness of Bryton Gardia R300L, Garmin Varia RTL515, and Wahoo TRACKR Radar. You can see that Varia has the most centered and brightest light.

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. However, this does not mean you should rely entirely on this device. Although Varia is reliable, you will get the following warnings during pairing.

Battery Life

Garmin claims up to 15 hours of battery life (day flash mode). I am getting around 14 hours, depending on the outside temperature (it’s shorter when it’s cold).

This is plenty of 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 an approved AC adapter). Still, the iGPSport SR30 lasts longer. The chart below shows the battery life of selected bike radars.

I also noticed no drastic decrease during the first year, which is good news. Of course, after 3 years, the battery degraded.

NOTE: The radar may reduce the battery life of your bike computer.

Reliability

I have already ridden over 15,000 miles (24,000 km) with this radar. Occasionally, it detects cars approaching from a sharper angle (from side roads), but they disappear from the screen quickly. It has never missed a car (false negative).

It gives a very low number of false positives—usually none for a several-hour-long ride. The opposite situation would be much worse, though. Imagine no alert when the car is approaching. It could end badly if you rely solely on the radar. With such a critical device as the cycling radar, you should not try to save every penny, and you should avoid the bad-performing radars.

Peloton Mode

Peloton mode is useful when riding in a group. The radar automatically detects the presence of bicycles or vehicles behind you within 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 higher than 11.18 mph (18 km/h), but it will ignore other cyclists in the group. The taillight will also be automatically dimmed not to dazzle others.

Also available at rei.com, performancebike.com, and tredz.co.uk

Varia RTL515 Cons in Detail

Micro USB Charging Cable

One of the biggest disadvantages of Varia is the use of a Micro USB cable and the absence of a USB-C port. Since many new laptops, chargers, and devices feature USB-C, Micro USB is a problem. I have multiple cables and have to think about which one to use. Additionally, Micro USB charging is slow.

Unfortunately, Garmin did not adopt the newer standard or contribute to its unification. However, we may see USB-C in a future release. We will see.
Update: The Garmin Varia RCT715 already features a USB-C port.

Compatibility Issues with non-Garmin Devices

The Garmin Varia RTL515 was initially only compatible with Garmin devices, but third-party manufacturers quickly followed with firmware updates and support. The good news is that most modern bike computers support ANT+ cycling radars.

However, only Garmin Edge cycling computers can wake up the Varia from standby mode, so you don’t have to turn it on and off. You can use some 3rd party bike computers to change light modes, though.

Unstable Mount

My experience with the supplied mount on my old bike with a round seatpost was good. However, on most non-round seatposts (other than the V-shaped one), the stem slips, so I have to adjust it when riding (after sprints, dismounts, or bumpy descents)

If you have a round seatpost, you can solve this problem by purchasing a fixed mount for the Garmin Varia RTL515. You can also find numerous 3D-printed mounts online for various seatpost shapes.

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:

No Possibility of Adjusting Light Modes

Unlike Magene L508, Varia does not allow you to adjust light modes and other settings. It will stay the same as you receive it. I understand why Garmin decided to keep things simple. For example, increased brightness would lead to shorter battery life and negative reviews. Still, its brightness is good enough. It’s actually one of the highest of all radars I tested. So you don’t even need to adjust it.

Garmin Varia RTL515 Alternatives

There are a few alternatives to the Garmin Varia RTL515. For a long time, Garmin was the only company producing cycling radars. This changed in 2022 when Magene and Bryton introduced their radars, and in the following years, when other manufacturers tried unsuccessfully to emulate Garmin’s success. Still, there are some worthy Varia alternatives:

• Magene L508 – offers better adjustability but gives more false positives and has a shorter battery life.
• Bryton Gardia R300L – has a better mount but gives more false positives.
• Garmin Varia RCT715 – has a camera, but it is too bulky, heavy, and expensive.
• Bike mirror

My Verdict

I honestly don’t know anyone who regrets buying the Garmin Varia RTL515. You will feel much safer with it. I take it on every swing. It’s one of those devices that you don’t need but will make your life easier. It’s the perfect upgrade. I use the RTL515 as a reference radar for all my cycling radar tests.

If the higher price tag bothers you, you might consider its alternatives. However, the Varia RTL515 is still the market leader in reliability and accuracy. I also think you should not try to save every penny on such a critical safety device as a cycling radar.

Also available at rei.com, performancebike.com, and tredz.co.uk

Garmin Varia RTL515 FAQ