The Garmin Varia RearVue 820 is a radar tail light that tells you about cars coming up behind your bike. Released Oct 16, 2026, JPY 46,800. It spots cars behind you from up to 175 m, and tells you the size of the vehicle and even when it moves sideways toward you.
The Shoe Nerd's top pick
The RearVue 820 is the generation that goes from telling you "there's a car or not" to "what kind of car, and how it's coming." Its 57 GHz radar stretches detection from the RTL515's 140 m to 175 m. It sorts vehicles into small, medium and large, and it picks up sideways movement too. For riders who want to look behind less and keep their eyes ahead, I recommend this unit.
Key points
- Detection of vehicles behind: up to 175 m. That's 35 m (25%) farther than the previous RTL515's 140 m
- Battery is about 24 hours in Day Flash. That's 8 hours longer than the RTL515's 16 hours, and about 30 hours with radar only
- Weight is about 90 g, 19 g heavier than the RTL515's 71 g. Charging is USB Type-C
A tool that tells you about cars behind without looking back
When you ride on the road in bike training, what bothers you most is behind you. Each time you look back, your eyes leave the road ahead.
The Varia is a tail light that watches that "behind" with radar. When a car comes up behind you, it alerts your cycling computer screen, smartphone or a compatible watch. The RearVue 820 is its new generation.
Triathlon bike gear as a whole is collected in our triathlon bike gear article. Here we read only the RearVue 820.
When does the Varia RearVue 820 come out? Price and official figures
| Item | Varia RearVue 820 |
|---|---|
| Release date | Oct 16, 2026 (pre-orders from Oct 9) |
| Official price | JPY 46,800 |
| Weight | About 90 g |
| Dimensions | 98.9 × 25.9 × 43.2mm |
| Vehicle detection | Up to 175 m (57 GHz, 60° width) |
| Battery | Radar only about 30 hours / Day Flash about 24 hours / Proton about 15 hours / Steady and Night Flash about 10 hours |
| Water resistance | IPX7 |
| Charging | USB Type-C (with cap) |
It connects over ANT+ and Bluetooth. It works with Edge X40 and X50 series cycling computers and the free Varia app. Some Garmin watches alert you by vibration, and some models announce an approaching car by sound.
Image: Rakuten Ichiba
Garmin Varia RearVue 820
Lowest price on Rakuten Ichiba: JPY 46,799 (as of 10/17). Prices change daily.
RecommendedSee it on Rakuten IchibaHow is it different from the RTL515? What changed from the last model
| Item | RTL515 | RearVue 820 | Difference |
|---|---|---|---|
| Vehicle detection | Up to 140 m | Up to 175 m | +35m |
| Battery (Day) | 16 hours | About 24 hours | +8 hours |
| Battery (steady) | 6 hours | About 10 hours | +4 hours |
| Weight | 71g | About 90 g | +19g |
| Visible distance | 1.6km | 2km | +0.4km |
Detection: from 140 m to 175 m, 25% farther (35 ÷ 140). If your bike is going 30 km/h and the car behind is going 60 km/h, you're closing at about 8.3 m/s. The alert arrives about 21 seconds ahead at 175 m and about 17 seconds ahead at 140 m, so you gain about 4 seconds.
What it tells you: new is the sorting of vehicles into small, medium and large, shown as icons, plus detection of sideways movement. It also adds "speed-following tracking," which follows a car that keeps traveling behind you at your own speed.
Brake light: an accelerometer and gyro sensor detect slowing and stopping, and the light signals to the rear. The RTL515 didn't have this role.
Weight and charging: it's 19 g heavier, but Day battery life is 1.5 times longer (24 ÷ 16). Charging switches from microUSB to USB Type-C, so it's easier to carry a single cable.
What I like
The battery covers 1 day of training. About 24 hours in Day Flash and about 30 hours with radar only. Even after a few long weekend rides in a row, you aren't chasing a charge every time.
It tells you "what kind of car." It shows 3 size categories and sideways movement, combined with speed, as levels of danger. As someone who races triathlon, what I want to know is whether a truck is moving toward me or a car is pulling out to pass.
Daytime brightness went up. Day Flash is 100 lumens, brighter than the RTL515's Day mode at 65 lumens. The visible distance also stretches to 2 km.
Things to watch
- There are situations where it won't alert you. Detection of cars at the same speed is said to be limited in snow, ice, heavy rain, or when it isn't mounted correctly. Even with radar, you can't drop the habit of checking with your eyes.
- It's heavier than the RTL515. About 90 g, up 19 g. It mounts on the seat post, so on a race bike where you shave every gram, some riders will mind.
- You need a device to receive alerts. The vehicle size display shows on a compatible Edge or the Varia app. If you only have an older Edge, what it can show is limited.
Who is the Varia RearVue 820 for?
- A good fit for: riders who spend long hours on road bike training. Riders with an Edge X40 or X50, or a compatible Garmin watch, who want to know about cars behind by screen or vibration. Riders who want to move up from the RTL515 to 175 m detection and a 24-hour battery.
If your days are mostly on a trainer or a closed course, the radar has less to do.
Price and where to buy
| Model | Official price | Rakuten price range |
|---|---|---|
| Varia RearVue 820 | JPY 46,800 | JPY 46,799 |
The same box holds the unit, the mounting parts and a charging cable. The new seat-post mount is a shape that fits many road and gravel bikes.
Before you buy, check whether your Edge is a compatible X40 or X50 series. If you want to receive alerts on a watch, check whether your model is on the compatibility list. For a watch that suits long rides, read our Enduro 4 article.
Image: Rakuten Ichiba
Garmin Varia RearVue 820
Lowest price on Rakuten Ichiba: JPY 46,799 (as of 10/17). Prices change daily.
RecommendedSee it on Rakuten IchibaFAQ
When does the Varia RearVue 820 come out?
It went on sale on Oct 16, 2026. Pre-orders opened on 10/9. The price is JPY 46,800, tax included.
What's the difference between the Varia RearVue 820 and the RTL515?
Detection range stretches from 140 m to 175 m, and Day battery life from 16 hours to about 24 hours. It adds vehicle size categories, side-movement detection and a brake light, and weight goes from 71 g to about 90 g.
Can the Varia RearVue 820 be used with just a watch?
Some Garmin watches alert you to approaching cars with vibration, and some models also use sound. But the vehicle size display shows up on a compatible Edge or the Varia app. How to compare watch battery life is covered in our fēnix 9 article.
