Cyclists Hub is supported by its readers. We may receive a commission if you buy products using our links.
All content on Cyclists Hub is written by humans, not robots. Learn More
Garmin has just introduced a brand-new cycling radar, the Varia RearVue 820, and it should be the most advanced rear radar the company has ever made. It will be available to order on February 6th, and I will do my best to get my hands on it as soon as it becomes available here in Czechia.
I have tested previous Garmin Varia models extensively, including the popular RTL515 and RCT715, and I have also spent a lot of time riding with cheaper Chinese alternatives. Some of those budget options work surprisingly well, but Garmin has consistently delivered better detection reliability and accuracy. With the RearVue 820, Garmin is clearly pushing that lead even further, and I suspect, given Garmin’s reputation, that it will instantly become the best cycling radar on the market.
What’s New Compared to Previous Garmin Radars
At first glance, the RearVue 820 looks like a familiar Garmin radar with a tail light, but nearly every key area has been upgraded. Here is a bulletpoint summary of what’s new. I will dive deeper below.
- Increased maximum detection range to 175 meters (from 140m)
- Wider beam width 60° (up from 40°)
- Vehicle size classification (small, medium, large)
- Threat level assessment based on speed, size, and position
- Lane-change detection when paired with compatible Edge devices or the Varia app
- Same-speed vehicle tracking for cars traveling at a similar speed to you
- Garmin’s brightest tail light yet, visible up to 2 km (up from 1.6 km)
- Higher maximum brightness of 100 lumens in day flash mode (up from 65)
- New brake light function that activates when you slow or stop
- Longer battery life with up to 24 hours in day flash mode (up from 16 hours)
- Up to 30 hours of battery life in radar-only mode
- Custom light patterns via the Varia mobile app
- Updated design with a new seatpost mount
- Expanded alert options on Edge devices, smartphones, and Garmin smartwatches, including haptic and beta voice alerts
- Higher price $299 (up from $249)
The radar itself is more powerful and more precise, with a wider field of view and a detection range increased to 175 meters (up from 140m on RTL515). The tail light is brighter than ever, visible from up to 2 kilometers, and Garmin has added a brake light that reacts when you slow down or stop.
There is also smarter vehicle tracking, including vehicle size classification, threat levels, and lane-change detection when paired with compatible Edge computers or the Varia smartphone app. Battery life has been improved too, with up to 24 hours in day flash mode or 30 hours in radar-only mode.
RearVue 820 vs. RTL515
The RTL515 has been Garmin’s most popular radar for years, and for good reason. It is reliable, simple, and just works. The RearVue 820 builds on that foundation rather than replacing it entirely.
Detection range on the RTL515 is around 140 meters, while the RearVue 820 pushes that to 175 meters. That extra distance may not sound dramatic, but in real-world riding, it gives you more time to react, especially on fast roads or descents.
The beam width is another big upgrade. The RearVue 820 offers a 60-degree beam width, compared to the narrower, 40-degree coverage of the RTL515. This should help with vehicles approaching from curves, offset lanes, or uneven road geometry, where older radars could occasionally miss or delay alerts.
Lighting is also significantly improved. The RTL515 tops out at 65 lumens in day flash mode, while the RearVue 820 reaches 100 lumens. Visibility is claimed to be up to 2 km, which is a meaningful upgrade for daytime riding.
The biggest functional difference is intelligence. The RTL515 only shows approaching dots and relative speed. The RearVue 820 adds vehicle size classification, threat levels, and lane-change detection. On compatible Edge devices, this means you are not just warned that something is coming, but also given more context about how serious that approach might be. Now, you will know if it is a truck, a car, or a motorbike. Although, I’m curious about how ease it will be to distinguish these on small bike computer screens.
The RearVue 820 also introduces a brake light, something the RTL515 does not have (but many Chinese alternatives do). When the device detects deceleration, it switches to a unique flash pattern to warn traffic behind you. This is a subtle feature, but a helpful one.
Battery life is better too. The RTL515 offers up to 16 hours in day flash mode, while the RearVue 820 stretches that to 24 hours, which is a big improvement for long rides or multi-day trips.
If you already own an RTL515, it is still a very capable radar. The RearVue 820 is not a must-upgrade for everyone, but for riders who want maximum visibility, smarter alerts, and the latest safety features, the differences are meaningful.
More Powerful Radar and Smarter Detection
Garmin says the RearVue 820 uses its most powerful and precise radar technology yet. It tracks vehicles up to 175 meters away and uses a wider radar beam to improve consistency. I’m curious on how helpful the multi-line detection will be. This is something Trek CarBack introduced, but its execution was not exactly on point.
The new same-speed vehicle tracking is also worth mentioning. The current generation didn’t show cars traveling the same speed as you, making you to lose track of them. The new radar should change this.
Advanced Alerts and Device Integration
Like previous Varia radars, the RearVue 820 works with Garmin Edge computers, the Varia smartphone app, and Garmin smartwatches. It will also work with 3rd party head units, but its functionality will be limited (unless 3rd parties figure out a way how to cooperate with Garmin or implement the multi-line tracking).
What’s new is how much information you can see. On supported devices, alerts now include vehicle size, threat level, and lateral movement. Lane-change detection is especially interesting, as it can show when a car moves away from you rather than staying dangerously close. This is something not many will be able to copy, as it’s very challenging to do right, as desribed in this technical dive into bicycle radars.
Garmin smartwatches can also deliver haptic alerts, and some models can provide voice alerts through the Public Beta program. This could be very useful if you ride without a bike computer.
Brighter Tail Light and Brake Light
The RearVue 820 features Garmin’s brightest rear light so far. In day flash mode, it reaches 100 lumens and remains visible from up to 2 kilometers.
The brake light is a nice-to-have feature. When the unit senses that you are slowing or stopping, it triggers a distinct flash pattern. This is something we already know mainly from the Chinese alternatives.
Light Modes and Customization
The RearVue 820 offers four light modes: day flash, night flash, solid, and peloton mode. Peloton mode reduces glare for riders behind you while keeping radar functionality active.
Using the Varia mobile app, you can customize light patterns to match your riding style and conditions. This level of control is something cheaper radars usually lack.
Battery Life and Practical Use
Battery life is one of the strongest points of the RearVue 820. You get up to 24 hours in day flash mode, 15 hours in peloton mode, 10 hours in solid mode, and 30 hours in radar-only mode. For most riders, this means charging once every few rides instead of after every ride.
Design and Mounting
The RearVue 820 weighs 90 grams and has an IPX7 water rating. This makes it about 19g heavier than the RTL515, not counting the mount itself. The one on RV820 should be more stable, but it is also bulkier, so the overall total weight will be higher.
Will It Sell Well?
At $299.99, the Garmin Varia RearVue 820 is clearly a premium product and the most expensive cycling radar without a camera. Chinese alternatives are much cheaper, but none currently offer this combination of detection accuracy, reliability, and visibility.
If Garmin’s real-world performance matches the specs, the RearVue 820 could become the new gold standard for rear radars. Stay tuned for my in-depth review. So far, I only have one complaint. The name is terrible! What do you think of this radar? Let me know in the comments below.
Preview picture source: Garmin