The Garmin Varia was one of the first bike radars on the market and the only radars for a number of years that offered a clever way to monitor traffic behind a bike while riding. In recent years, the Garmin patent has expired which has opened the flood gates to everything from Trek to Bryton branded bike radars with more features and brighter lights. The Garmin Varia Rearvue 820 is Garmin’s long awaited update to their radar that puts Garmin back at the top of the bike radar market. Despite the increased competition, the retail price of the radar has actually increased to $299.99 which includes an updated slim seatpost mount. The major update of the RearVue 820 is the improved detection range of 175 meters and software updates that allow for object tracking and classification. The new display features require a compatible Garmin GPS headunit or the Varia App as Garmin is moving toward encrypted bluetooth communication.
The Garmin Varia RearVue 820 is a long awaited update to Garmin’s radar that brings best-in-class performance at a premium price point.
| Rating | 9.5 / 10 |
| Retail Price | $299.99 |
| Measured Weight (in g) | 87 (radar), 36 (seatpost mount) |
| Likes | + Impressive detection range and spread detects cars well before you hear them + New object identification and tracking ensures vehicles at same speed stay on radar display and help differentiate between cars / buses / bikes + Update slim seatpost mount and USB-C charging address major annoyances of previous radar models |
| Dislikes | – Garmin increased the retail price despite all the additional competition in the radar market – New display design uses proprietary BLE communication that requires a Garmin GPS or the Varia App and defaults to standard dots on other devices – The taillight design is visible but feels dated and there is a lack of a multi-led battery indicator on the device |
| Where to Buy (US) | Garmin |
UNBOXING
The Garmin Varia RearVue 820 comes in a compact gray cardboard box with large Garmin branding and a glossy graphic of the radr printed on the top. Inside the box you’ll find:
- Varia RearVue 820 radar
- Seatpost mount + various adapters for round / aero / D shaped seatposts
- Safety tether
- Instruction manual
- Safety pamphlet
Garmin includes everything you need to install the radar and to start riding. The included pads for the seatpost mount also have angle values printed on them which make it easy to find the right orientation for your bike’s geometry.
MOUNTING
Not surprisingly, the Garmin Varia RearVue 820 uses the same Garmin quarter turn mount as the other Varia devices. This is the standard two raised tab design that rotates in place onto a corresponding mount with slots. You’ll notice that Garmin has oriented the tabs vertically as they’ve done with previous Varia radars. Garmin also includes a new slimmer seatpost mount that is designed to put the radar closer to the seatpost. It’s a multi-piece design with a plastic base, rubber baking and a rectangular shaped rubber strap. There are enough adapters to handle aero, D, round and just about any type of seatpost in between. Garmin has also designed the radar to be mounted upward (with the power button on top) or downward (button on the bottom to accommodate different bike geometries. The default setting on the radar is to autodetect the orientation using a built-in sensor, but you can also override it to an explicit orientation.
FIT & FINISH
Visually, the Garmin Varia radar has an updated and more modern design that the previous Varia radars. The Varia RearVue 820 retains a rounded corner on one side while the other side is squared off. A translucent red lens cuts through the entire body with a large center LED on the rounded corner, two LED side markers and a black radar surface. The radar still has a distinctive Garmin appearance while looking more modern thanks to the smooth curves and extended red lens. In terms of dimensions, the RearVue is 3.9” x 1.0” x 1.7″ (98.9 x 25.9 x 43.2 mm) which is similar in size to most radars on the market. There is a small rectangular shaped power button with a multi-colored RGB LED status indicator next to it on the side closest to the radar surface.
It’s a similar design to other Garmin devices, such as the Varia Vue front camera, with a confusing number of colors and flash patterns to indicate different states. A slot for the safety tether is right next to the button and can be used as a backup if you were to experience a mounting failure. Subtle Garmin logos are on each side of the radar above the translucent red lens side markers. On the back of the radar you have a large cover for the USB-C charging port, an upgrade from the Micro USB slots of previous Garmin devices that is long overdue. Garmin has also left exposed bolts on the backside of the radar to allow the battery on the Varia RearVue 820 to be user replaceable in anticipation of EU rules requiring it.
In terms of the taillight design, Garmin has stuck to their standard single LED design with separate marker lights. There is a focused rear facing LED that provides up to 2 km visibility with a narrow beam that ensures you are visible from long distances. The red transparent lens reflects some of the light to help with side visibility, along with two dedicated LEDs on each side of the radar with separate lens cutouts. While this design works well, it’s pretty basic compared to more advanced taillights or something like the Magicshine R300 radar’s COB LED stripes. You can operate the taillight in four modes out of the box including a fifth light-off and radar only option which gives you the maximum runtime.
USER INTERFACE
There is a single power button on the top of the radar which can be held to turn the radar on or off. You can also enter pairing mode by holding the button for two seconds with the light off. Note, the power button itself is surprisingly small and thin so it’s not that comfortable to use. An RGB LED next to the power button is used to indicate the device status. There are a variety of colors and flashing patterns to reflect the state of the device, but you’ll need the manual to understand all of them. Garmin has also added a demo mode which can be activated by holding the power button for ten seconds which will generate fake data to help demo the device and view the alerts without going into traffic. To exit demo mode you press the button six times. For all the other settings, you need to use the Varia App which lets you adjust the brake sensor mode, light mode ordering and even create custom modes.
VARIA APP
Garmin provides a free Varia App for viewing radar information as well as customizing the behavior of the Varia RearVue 820. It’s a simple app that can be used as a substitute for a GPS cycling computer, something that is convenient for commuting, or just to configure the radar. The main screen o the app has a two lane display with side color indicator that mimic a GPS radar display to show approaching vehicles. Connecting the radar using Bluetooth allows it to show up under devices with four main options: light modes, device settings, software updates and a checkbox for “Radar Thread Mode” (i.e. the special flash mode shown when cars are detected). Light modes allows you to change the current output mode, re-arrange them or remove modes you don’t want. Garmin has even added a custom mode creation option that lets you create constant modes or a custom flash mode comprised of multiple constant or flash settings.
Within the app there are also some options to adjust the behavior of the radar. One is the device orientation, by default an internal accelerometer will determine if the taillight is upright or downward but you can also override the setting. The brake sensor mode can be disabled or switched between a high constant mode or a flash mode if braking is enabled. We were surprised by the lack of a sensitivity option for the brake sensor as most apps allow you to switch between low / high sensitivity for brake sensors. Otherwise, the app is easy to use to customize the radar behavior or as a standalone app for riding without a GPS.
RIDING IMPRESSIONS
At this point, it feels like every company has a bike radar from big brands like Trek to smaller companies like COOSPO, Magene and Ravemen. It’s not clear why Garmin hasn’t released an updated radar that at least features USB-C charging until now, but we’re happy to see the RearVue 820 enter the market. We paired the radar with the latest Garmin Edge 850 GPS unit to take advantage of the updated display features. The radar has already been on the market for several months so many of the launch-day bugs have already been patched and addressed with software updates – one reason we’d recommend waiting before buying new technology. At the time of this review, everything worked nearly flawlessly right out of the box. The Garmin radar has always had one of the best algorithms on the market, and the RearVue 820 continues that legacy with even longer distance detection and tracking.
We primarily kept the taillight in day flash mode (100 lumen with a claimed 30 hour runtime) with the brake sensor of to get the best runtimes and found the taillight to be bright and highly visible. While it isn’t as fancy or modern with the three simple LED indicators, it works well and has great side visibility. On the road, the software updates allow the RearVue 820 to track vehicles from impressive distances with almost no false positives. The new display replaces the traditional colored dots with rectangular shaped objects that mimic the size – narrow ones for bikes / motorcycles and longer ones for buses or semi trucks. While the color-coded warning indicators inside each vehicle are a big distracting it works well and even tracks the vehicle position behind you. You can see cars move to the side as they approach and pass you which gives you more situational awareness as well as a potential heads-up if a vehicle is too close to you.
The new display works well, but it’s disappointing to see Garmin moving toward proprietary transmission protocols making this new feature only available on Garmin devices or the Varia App. You can still use the radar with other GPS units to take advantage of the improved detection range and object tracking to keep cars on the radar traveling at the same speed but it will use the standard dot display. Otherwise, we were pretty impressed with how well the radar handled dense traffic, and was able to even track motorcycles alongside vehicles. Garmin’s software updates ensure vehicles remain on the display even as they travel at the same speed as you which is an impressive feat and addresses the flaw all radars have that rely on speed differentials.
THE VERDICT
Overall, we found the Garmin Varia RearVue 820 offers impressive radar performance along with long awaited upgrades to the charging and mount designs. Garmin has given the radar a visual facelift with a sleeker design that has more transparent lens and a raised radar surface. There is finally USB-C charging as well as a sleeker seatpost mount that puts the radar closer to the seatpost and feels more robust. The biggest improvements are inside the radar with longer detection range and software improvements that can track objects as well as classify them by size. It’s a nice update the replaces standard dot displays with rectangles sized based on the object that makes it easy to distinguish between bikes, cars, and larger vehicles like buses. The main negatives with this radar is higher price, despite all the competition, a proprietary communication protocol that requires Garmin devices for the new display features and a somewhat dated LED design. That said, it’s safe to say the Garmin Varia RearVue 820 is one of the best performing radars on the market.
Disclaimer: The product for this review was provided by Garmin. The views expressed on this website are solely those of the authors and are here to help people make an informed choice before a purchase. The authors or the blog itself does not get any monetary compensation from the product manufacturer or third-party websites/vendor links that are posted here.