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Garmin Varia RTL515 rear light review

22 Jan 2021

Garmin’s radar-equipped rear light helps you keep an eye on the road behind a lot more easily

Cyclist Rating: 
Effective system to alert you to approaching vehicles • Light pattern changes as vehicle approaches
Expensive • Only one alert for a convoy

The Garmin Varia lights are designed to team up with Garmin's GPS computer head units to help up your road presence. There’s the functionality to control them via your computer. But more importantly, the Garmin Varia RTL515 also transmits traffic information to the head unit.

That’s thanks to a built-in rear facing radar. As a car (or at a closer distance a faster cyclist!) approaches, it picks up their relative movement and flashes up an alert on your computer. It’s easy to pair with Edge series cycling GPS computers and you can also download a widget to connect it to Garmin’s smartwatches.

You can use the Varia radar with some other makers' computers too, including Wahoo's Elemnt Bolt and Roam and the Hammerhead Karoo 2.


Using Garmin’s top spec Edge 1030 Plus unit, there’s an audible alert once a vehicle is in range of the radar and the sides of the screen turn red. On one side, a white dot appears which indicates how far away the vehicle is and its speed of approach.

Multiple vehicles usually show up as separate dots, although if they’re close together and travelling at the same speed, they may be merged into one.

Buy the Garmin Varia RTL515 rear light from Wiggle now

Once the vehicle has passed, the sides of the Edge’s screen briefly turn green to indicate that it hasn't detected anything else approaching.

Garmin quotes a 140m range for the Varia RTL515, but on a straight road vehicles were typically detected at several hundred metres more than this. The system worked as well for me in wet and dry conditions and a good coating of road grot thrown up by the rear wheel did not seem to affect it.

To get an alert, a vehicle has to be approaching you, so on occasions when cars followed behind on narrower roads at the same speed as I was going, they would disappear from the radar, then reappear when they overtook. You do need to keep alert to what’s going on behind rather than just relying on the Varia.


The Garmin Varia RTL515 has its own app for iPhone and Android that you can use with it. This provides much the same view of approaching vehicles’ speed and relative position as displayed on the Edge, and also lets you change the light’s set-up.

It’s a useful alternative if you want to use your smartphone as a bike computer, which is likely to appeal to commuters.

You can also buy a separate bar-mounted display unit and the Varia light works with some third party riding apps – Garmin quotes RideWithGPS. With both ANT+ and Bluetooth connectivity, there are plenty of pairing options.

Reactive lighting

You can select from two constant and two flashing light modes on the Varia RTL515, with quoted run times of between six and 16 hours. As well as alerting you to approaching vehicles, the light also changes its lighting pattern as they near, to up the chances that they’ll register your presence.

A constant taillight will start to flash, while a flashing light will up its frequency and intensity.

To get a good view of the road behind, the Varia RTL515 needs to be mounted quite high on your seatpost, where it won’t be obstructed by the rear wheel or a rack, and it needs to point horizontally back.


There’s a chunky mount fixed with a rubber band and Garmin provides inserts to fit round, flat-backed and teardrop seatposts. The light uses Garmin’s usual quarter turn to fix to this.

Buy the Garmin Varia RTL515 rear light from Wiggle now

There’s a tendency for the round post adapter to rotate around the seatpost as you ride, so it’s worth checking periodically to make sure it’s still facing to the rear. That’s unlikely to be an issue with the other adapters though.

Along with its mount, the Varia RTL515 weighs 100g, so it’s quite heavy for a rear light, while its £170 price tag is likely to put off many potential users.

But it’s an effective way to ensure you know what’s coming up behind and to alert drivers to your presence. That lets you concentrate more on your riding and what's ahead, while still keeping aware of following traffic.

All reviews are fully independent and no payments have been made by companies featured in reviews


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