Tested: Garmin Varia RearVue 820 – is it still the benchmark?

I’m already a radar light convert and have been riding with one of Garmin’s competitor radar lights for about a year.

If you’re unfamiliar with the concept, these rear light units alert you to approaching vehicles from the rear with visual and audible prompts on your bike computer screen. If you’ve not tried one, you might think it’s not something you need. I thought the same until I started using one, and I now dislike riding with my rear radar.

When Garmin asked if we were interested in testing their new Varia RearVue 820, I jumped at the chance. It’s the first full update from the market leader in six years, and I’m sure many tech lovers will be impressed with the advances that Garmin has made.

The new unit shows more information on the screen, offers brighter light, uses USB-C charging, provides longer battery life, and offers a longer detection range – all great improvements.

The new advanced vehicle tracking detects a vehicle’s size and side-to-side movement. It categorises threat levels as the vehicle approaches from behind, with alerts displayed on compatible Garmin cycling computers or in the Varia smartphone app. Garmin says this is thanks to more powerful and precise radar technology.

It’s important to note that the advanced tracking features, such as vehicle sizing and side-to-side movement detection, are only available on Garmin x40 and x50 devices. If, like me, you have an older Garmin device or another brand of computer, the RearVue 820 will work just like any other radar.

As a ride with a Wahoo Roam 3, I was not able to review those advanced features. However, from my experience with a radar rear light, simplicity on a computer screen while you’re riding is paramount for me. My eyesight is not great, and I choose not to wear prescription glasses most of the time. This doesn’t mean that I’m a hazard on the road, as I can still read everything I need to on my bike computer and other objects while I’m riding.

Radar feature

It’s strangely comforting to know if a car or other vehicle is coming from behind even before you can hear it. It’s also great for quiet vehicles like electric cars or other cyclists.

Garmin says the new model detects vehicles 175 metres behind with a 60 ° field of view. Although I didn’t conduct a scientific experiment, I assume it is relatively accurate because the visual alert appears in most situations before you hear the vehicle approaching.

Once again, for those who haven’t used a radar light before, on my computer screen an orange stripe appears on the right-hand side, and a small graphic indicating a vehicle moving up the screen represents the approaching vehicle. If there is more than one, then multiples appear. Once the vehicle passes, it disappears, and a green strip appears.

One of the big selling points of the new Garmin Varia RearVue 820 is its ability to detect vehicles travelling at the same speed (or bicycles). Most other models on the market, including the one I’ve been using for a while, only detect vehicles that are moving faster than you. If they follow you at the same speed, they tend to drop off the screen until they accelerate. The new model keeps them on your screen even when they travel at the same speed. While this feature is helpful in some situations, I found that when riding with riders behind me, it constantly showed them on my screen. This meant that to detect cars coming from behind, I had to look closely at the screen to see an additional vehicle approaching.

The same speed feature worked fine for me when I rode alone, as it was helpful to know when a vehicle that had come from behind was still there. Perhaps Garmin could make it possible to turn this feature off in certain situations. I note that if I had a compatible computer, I could have changed the vehicle size the unit detects, which may have solved the issue.

Light feature

As a rear light, it definitely did the job. Obviously, when I’m riding, I can’t see it, but my riding buddies told me it was bright and easy to see. It even gets brighter when it detects an approaching vehicle from behind, helping alert the driver. It then dims to normal levels when the vehicle has passed.

Garmin says it can be seen over 2 km away and offers multiple light modes, including day flash, night flash, solid mode, and peloton mode.

Using the Garmin Varia app, you can customise the flash patterns to suit your needs. I found I used either the solid peloton mode when I rode with groups or the night-flash mode when I was alone.

Battery life & charging

It charges in 2.5 hours via the USB-C port, and Garmin says it will have battery life of up to 24 hours in day flash mode and up to 30 hours in radar-only mode. I didn’t measure its longevity, but in all the time I’ve used it, I’ve never run out of power. I was also impressed to learn that it has a replaceable battery, which is better for the environment and hopefully better for your hip pocket.

Mounting

It came with a seatpost mount featuring three rubber inserts designed to fit different seatpost shapes. One of them fit my squarish Specialized Tarmac seatpost very well. It is held in place by a rubber strap that is not dissimilar to the one used to hold the cadence sensor on my crank (also Garmin-branded). The strap was quite hard to stretch to attach it to the seatpost, but once in place, it feels very secure and solid. The light attaches via a small quarter-turn mount, fitting snuggly just below my saddle.

Summing up

The new Garmin Varia RearVue 820 is most certainly the Rolls-Royce of rear light radar units, and I couldn’t fault its performance. However, without a newish Garmin computer, quite a few features are not accessible. I would highly recommend it to anyone with a Garmin X40 or X50, and I’d certainly recommend getting a radar light to any safety-conscious rider.

The retail price is $469.

More info here.