A radar and light integrated into one nifty unit.

The Garmin Varia RTL510 is a rear bike light with an integrated radar system designed to alert cyclists of vehicles approaching from behind. It’s Garmin’s second version of the radar system featuring a sleeker design and easy integration with Garmin Edge cycling computers. On rural roads riding alone when I am prone to be startled by a car speeding by, it gave me a bit more peace of mind and allowed me to adjust my line to give the vehicle space if there was adequate room for the vehicle to pass.

Riding with Radar

While most cyclists have gotten used to constantly looking over their shoulder for oncoming traffic, the Varia RTL510 detects oncoming cars far before my own senses could. While it didn’t replace my senses, I liked that it warned me if a vehicle was approaching.

The light was easily synced with a Garmin Edge 520 Plus and the light can even be turned on and off using the head unit. First, there is a beep and then a column appears with a dot at the bottom representing the car and it’s position relative to you. The radar system can detect vehicles 140 metres away and an alert is sent to your head unit. When the column turns red, it means the vehicle is approaching at high speed. The column is amber when a car is detected and green when the coast is clear.

The radar is able to detect multiple vehicles giving you a warning if multiple vehicles are about to make a pass. In a group, I could then give a warning to others with a “car back.” When I was riding alone I was less likely to get startled or be caught swerving around a pothole just as a vehicle was passing. In windy conditions when my senses were impaired, I didn’t have to look back quite as often.

The bundle head unit allows you to use the light if you don’t have a compatible Garmin Edge computer.

In a few cases, the Varia RTL510 mistook a cyclist for a vehicle when I was riding in a group. Most of the time, however, it successfully differentiated between rider and car. Even with a half-dozen riders in my draft, it could still detect approaching vehicles.

In the city on busy streets, it’s usefulness was a bit less apparent. With vehicles nearly constantly passing, the early warning wasn’t very useful. It also was much more likely to be mistakenly triggered. However, on quieter city roads or routes with fast traffic, I enjoyed having it.

While looking down and tracking the vehicle as it approaches can be helpful, the beep was often sufficient warning for me. If I was deep in conversation with my riding partner or lost in my thoughts, it brought me back on the road. The warning you get won’t change the behaviour of the driver but it was certainly welcome on my end. The reliable warning really made riding alone more enjoyable.

Rear light integration

The provided mount easily straps onto any frame. There’s also a longer elastic for aero frames.

While the warning I received was always a good thing, the red light integrated into the radar gave me a bit more confidence the passing driver would also notice me. Regardless of whether you have the light on the solid or flashing setting, the 60-lumen rear light will flashes at a higher frequency when a car approaches. This increases the chance the vehicle will not only see you but perhaps pass with more care. The light has a 220-degree range as well so vehicles will be able to see you from a variety of angles. The battery life with the light on the flash mode is rated by Garmin at 15 hours while on the solid mode it should last about 6 hours.


The early warning I got from the Garmin Varia RTL510 was always welcome because it would detect vehicles far before I could. While it won’t stop a driver from passing close, it does provide some notice and that was never a bad thing. I liked that I could track vehicles and that the rear light would respond to the proximity of the vehicle giving me more confidence on quiet roads.

On rides in the country where vehicles can approach fast from seemingly nowhere, it’s an extremely useful tool to have at your disposal. It eliminates the surprise of a vehicle coming up to you giving you an opportunity to move over or take your place in the lane if there isn’t room for the vehicle to safely pass.

At $270, the Varia RTL510 is not cheap but it’s unique ability to notify you of approaching traffic and the fact it comes equipped with a powerful and long lasting rear light definitely give it value. With the radar display unit in the bundle, the light retails for $400.

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