Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In


Tech & Wearables

Garmin Varia RVR315 and Garmin Varia RTL515 review

This rear-facing radar provides warning of approaching vehicles, and their relative closing rate. And it just might save your life.

Review Rating


The Garmin Varia RTL515 and Garmin Varia RVR 313 rear-facing radar provide audible and visual alerts to users about vehicles approaching from up to 145 meters away.


Eyes in the back of your head; lightweight; RTL515 doubles as a tail light


May accelerate bike computer battery drain

Our Thoughts

The Garmin Varia Radar provides lifesaving warnings of traffic approaching from behind. It has, on more than one occasion, saved me from getting plowed by an overtaking car. While it seemed like the Varia radar taxed bike computer batteries — it was hard to quantify exactly how much — this was a worthy trade-off.







Don't miss a moment from Paris-Roubaix and Unbound Gravel, to the Giro d’Italia, Tour de France, Vuelta a España, and everything in between when you join Outside+.

The Garmin RVR315 ($149) and its larger, 70g sibling with a taillight, the Garmin Varia RTL515 ($199), are extraordinarily effective on-the-bike safety accessories. While they are not exactly a second set of eyes in the back of your head, they are the next best thing. When paired with a compatible GPS, they detect and display warnings of traffic approaching from the rear, allowing for preparation and reaction, should it be necessary.


Garmin Varia RVR315 and RTL515
The Garmin Varia RVR315 and RTL515 with a taillight. Photo: Greg Kaplan

Varia setup and configuration

Each Garmin Varia radar is supplied with a mounting kit for affixing it to nearly any shape seatpost (we tested on a round post and an aero post, as well as more angular, almost square posts) using heavy-duty, soft elastic bands. The mounting kit weighs just 34 grams, so it’s not going to throw a wrench into any Everesting attempts. The post-side of the mount is soft so it won’t damage your bike, while the rearward-facing side of the mount sports a ¼-turn-lock — exactly like the one on Garmin Edge bike computers — to grip the radar unit. The Varia shipped with several differently-shaped shims to accommodate a wide range of seat post shapes. Several lengths of elastic straps were also included, to ensure a snug fit on nearly any diameter and seat post shape.

Garmin Varia rear facing radar 1/4-turn mount
The Garmin Varia rear-facing radar was kept in place by the ubiquitous Garmin ¼-turn mount. Photo: Greg Kaplan


Garmin Varia quarter-turn mount
The Garmin Varia radar uses the ubiquitous quarter-turn tab to affix it to the seat post mount. Photo: Greg Kaplan

Both models of the Garmin Varia have a single toggle button, and an LED to indicate when the unit is powered on. And both radar units paired easily with bike computers that accept a radar signal over BTLE or ANT+.

We tested the Varia rear-facing radars on the Wahoo Elemnt Roam, and the Garmin Edge 520 Plus. While the respective displays had minor differences in how radar data were displayed, both head units worked equally well with the Varia radar.

The Wahoo Elemnt Roam worked flawlessly with the Garmin Varia radar. The vertical green column on the left side of the screen indicated no traffic approaching from behind. Photo: Greg Kaplan
Garmin Edge 520+
Garmin Edge GPS units displayed a visual indicator in the upper right side of the screen when a Varia radar unit was not powered on. Photo: Greg Kaplan

The Garmin Varia RVR315 and RTL515 units have configuration options that included on what side of the screen to show traffic indicators, single-tone or multi-tone alerts, and a toggle for color overlay indicators (when used with a bike computer that had a color display.) Both Garmin Varia models were configurable to trigger different alert tones emitted by the paired bike computer.

Garmin Edge 520+ with Varia settings
It was easy to pair and then access the Varia radar settings on a Garmin Edge. Photo: Greg Kaplan
Gamin Varia radar battery level
The Garmin Varia battery level was displayed in the sensor details screen. Photo: Greg Kaplan
Garmin Varia alerts settings
Varia alerts settings were accessed through the sensors menu on Garmin Edge GPS units. Photo: Greg Kaplan

The Varia RTL515 with a taillight offered additional configuration options when using a GPS that could manage an ANT+ light network. The Varia RTL515 taillight had three modes: steady on, strobe, and peloton mode (reduced output so as to not blind cyclists behind you). The sides of the Varia RTL515 enclosure allowed the tail light to be seen from either side, for additional visibility.

Garmin Edge 520 with Varia settings on display
It was very easy to set and test the Varia tail light. Photo: Greg Kaplan

Garmin also offers a free Varia mobile app that provided visual and audible alerts, just like when used with a dedicated GPS unit, but I have not used it. I didn’t like the idea of using my precious phone as a bike computer: GPS use is a massive battery drain, and I want my phone safe and fully-charged should I need it for any emergency.

Varia radar enhances situational awareness

When the Varia rear-facing radar was enabled, it indicated the number of vehicles approaching on-screen, and it color-coded their respective relative closing speeds. This relative speed indicator — how fast vehicles were approaching from behind relative to the speed at which the radar was moving — was triggered by the fastest moving vehicle detected.

When vehicles were closing on me at a low to moderate speed, an orange overlay appeared, along with a pulsing chime. When an approaching cyclist triggered the radar, and then two cars came into range, the faster of the two cars triggered the closing-quickly alert, which superseded the indicator for the approaching cyclist. When vehicles approached at great relative speeds, a red overlay appeared, and my bike computer made sounds like I had just scored a jackpot on a slot machine—it was impossible to ignore, even with a good bit of background noise.

The Wahoo Elemnt Roam displayed traffic closing from behind. A red vertical bar indicated vehicles closing at a relatively high rate of speed, while the number of vehicles was displayed in the vertical color-coded column, shown as car icons.
Garmin Edge 520 displaying approaching traffic
The Garmin Edge 520 displayed approaching traffic using orange overlays — with dots on the left side of the display — that indicated the relative closing speed and number of approaching vehicles. Photo: Greg Kaplan

Both the Garmin Varia RTL515 and Varia RVR315 were equipped with the same radar technology, and provided alerts for any vehicles which entered the 145-meter line of sight range. When riding on a mutli-use path next to a roadway, I received alerts about traffic closing from the rear and about 50 meters to either side.

When riding on twisty and undulating roads, the Varia radar acquired a signal but dropped it as soon as I was no longer in line-of-sight with any vehicles. The Garmin radar re-acquired vehicles when on flatter and straighter roads. This was the only flaw I could identify when using the Varia, and I realize that it’s not one Garmin can solve.

Varia battery life

Garmin claimed the Varia RTL515  gets about 15 hours of battery life; I got slightly more than 14 hours of use between recharging. Curiously, the Garmin Varia RVR315 without a taillight, got only about half of this battery life. Both Varia radar units have the same rubber battery door affixed to the unit body, and featured a plug to fit into the USB connection port, ensuring no moisture or dirt breach.

Garmin Varia radar low battery warning
Time to recharge the Garmin Varia radar. Photo: Greg Kaplan

I experienced an accelerated battery drain on both the Elemnt Roam and Garmin Edge 520+ when using the Varia radar. It was hard to quantify exactly how much less bike computer runtime I got between charges, but I think the tradeoff of a few minutes of battery life for the safety provided by the radar is — without question — a valuable tradeoff.

Garmin indicates that the Varia radar drains power from a connected Edge GPS at a rate equivalent to having three heart rate monitor straps connected, or about 10 percent faster than without the radar.

Garmin Varia verdict

The Garmin Varia RTL515 or the Garmin Varia RVR313 is part of my necessary riding gear, just like a helmet. I’m now mildly anxious when riding without it. I cannot recommend this cycling accessory enough.