See and be seen with the Garmin Varia rearview radar and tail light

Garmin’s clever tail light alerts you to approaching vehicles as well as upping your road presence

Garmin Varia rearview radar
(Image credit: Garmin)


Many road cyclists find keeping track of what’s happening behind them tricky. Without a view to the rear, it means turning around to look behind while keeping riding straight and always keeping their ears open for the sound of approaching vehicles.

The Garmin Varia RTL515 rearview radar helps you stay alert to traffic approaching from behind, upping your situational awareness. 

That’s thanks to its built-in rear facing radar, which can detect vehicles coming up behind up to 140m away and will alert you to their approach. There are lots of ways in which the Varia RTL515 can do this.

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 Pair to your Garmin bike computer 


The Varia radar can be paired easily to any Garmin Edge bike computer, using Bluetooth Low Energy or ANT+. A widget installed on the computer displays an alert on the side of its display screen which shows a symbol for each detected vehicle and how close it is. 

If your Garmin Edge has a colour display, its sides will also turn amber to show you that a vehicle has been detected. If it’s travelling fast, the screen edges will turn red. You’ll get multiple vehicle icons on the display when the radar has detected more than one vehicle behind. Once all detected vehicles have passed the screen’s sides will show green before turning back to the normal display colour.

In addition, the Edge will sound an alert to let you know that it’s detected a vehicle approaching from behind.

Garmin Varia rearview radar

The Varia can be used with Garmin's smartphone app as well as its Edge bike computers. There's the option to buy a radar unit without a built-in light too

(Image credit: Garmin)


The Varia RTL515 can be paired up with many of Garmin’s other devices, like its Fenix, Forerunner and Vivoactive smartwatches and activity trackers, which like the Edge will give you a visual and audible alert, and will also vibrate when a vehicle is detected.

If you’re not using a Garmin computer, it’s worth checking compatibility as several other brands now incorporate functionality into their computers to pair with and use the Varia rearview radar. You can also buy a dedicated Garmin Varia radar display unit which sits on your bars if you prefer not to use a computer.

A paired Garmin Edge also lets you adjust the Varia RTL515’s behaviour and how info is displayed on your Edge, change between the Varia’s lighting modes and check its status. Your Edge can vary the Varia tail light’s intensity and switch between modes automatically depending on how bright the daylight is and it will switch the Varia off when you switch off your computer too.

 Smartphone and app integration 


The Varia RTL515 will also work with an Android smartphone or an iPhone, pairing using Bluetooth. There’s a free Garmin app which will display the same information on approaching vehicles as an Edge computer. The phone will also vibrate and it will sound an alert, like the Edge. You can pair the tail light simultaneously with your phone and an Edge as well.

Varia integration is also built into some third party smartphone apps like the Ride With GPS cycling navigation app. 

 Adaptive lighting modes 


The Garmin Varia RTL515 doesn’t just tell you that there are vehicles behind you though. It also changes its lighting pattern as they approach to help alert drivers and up your road presence.

The light can be set up in a 20 lumen constant mode, an 8 lumen “peloton” constant mode (so you don’t dazzle other riders if you’re cycling in a group) or one of two flashing modes. 

Garmin Varia peloton mode

Peloton mode is designed not to dazzle following riders on a group ride

(Image credit: Garmin)


Day flash emits 65 lumens in an irregular pattern and can be seen up to one mile away, Garmin says. There’s a night flash mode too with 29 lumens output overlaid on an always-on lower intensity light. There’s good side illumination as well, with 220 degree visibility.

When it detects an approaching vehicle, the Varia RTL515 will change its behaviour. If you’re using a constant mode, it will begin to flash, while in the flashing modes it will flash more rapidly, returning to its pre-set mode once the vehicle has passed. 

Battery life is good, stretching from six hours in continuous or night flash mode right up to 16 hours if you’re using day flash. Charging via the included USB cable takes a maximum of five hours using a computer USB port or three hours using a mains adapter.

 Compact and robust 

At 98.6 x 19.7 x 39.6 mm and weighing just 71 grams, the Varia RTL515 won’t weigh you down. It’s designed to fit pretty much any bike’s seatpost, with a set of adapters to fit those with round, kammtail or teardrop sections. There’s a sturdy clamp held in place with a robust rubber strap to keep it secure and pointed horizontally backwards, so that the radar operates effectively. The radar attaches to the clamp quickly and securely using Garmin’s standard quarter turn mount. 

Garmin Varia rearview radar

The Varia RTL515 is compact, robust and weatherproof with good side visibility

(Image credit: Garmin)


The Varia is IPX7 waterproof as well, so it can cope with the spray from the rear wheel if you’re riding in the wet without mudguards. 

So the Garmin Varia RTL515 is a great way to up your situational awareness as you ride. Garmin points out though that it’s not a substitute for staying attentive and using good road sense as you ride.

The Varia RTL515 is priced at £169.99, but for that price it’s packing a lot of cutting-edge technical features and many riders will value the increased reassurance and road presence that it offers.

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Founded in 1891, Cycling Weekly and its team of expert journalists brings cyclists in-depth reviews, extensive coverage of both professional and domestic racing, as well as fitness advice and 'brew a cuppa and put your feet up' features. Cycling Weekly serves its audience across a range of platforms, from good old-fashioned print to online journalism, and video.