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
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.
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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.
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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.
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 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.
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 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.
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.
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.