Buy the Varia RearVue 820 unless you want video of what happens behind you. It sees farther, runs four times longer in day flash, and weighs 57 grams less. The RCT715 earns its spot for one reason: the camera.
Both are Garmin rear radars with a tail light built in. Both chirp at your head unit, phone or watch when a car is coming up from behind. Both save you the over-the-shoulder look that tends to pull your line out into the lane.
So the real question is not which radar is better. It is whether you want a recording of the road behind you, and what you are willing to trade for it.
What does the RearVue 820 do better?
Almost everything that is not a camera. Garmin calls the RearVue 820 its most powerful and precise radar yet, and the spec sheets back that up side by side.
The 820 picks up vehicles from up to 175 meters back with a 60 degree radar beam. The RCT715 tops out at 140 meters with a 40 degree beam. A wider beam means the radar is watching more of the road behind you, not just a narrow strip straight back.
The 820 also tells you more about what it sees. Paired with a compatible Edge or the Varia app, it shows whether a vehicle is small, medium or large, when it changes lanes, and how big a threat it is. Garmin lists the RCT715's threat classification as speed based only. The 820 also keeps tracking a car that is holding the same speed as you, the one that sits back there and never closes.
Then there is the light. Garmin rates the 820 at 100 lumens in day flash and visible from up to 2 km. The RCT715 is 65 lumens and 1.6 km. The 820 adds a brake light that changes its flash when you slow or stop. Garmin lists a brake light on the 820's spec sheet and not on the RCT715's.
Battery is where the gap gets silly. The 820 is rated for 24 hours in day flash, 15 in peloton mode, 10 in solid or night flash, and 30 with the light off in radar-only mode. The RCT715 is rated for 6 hours in day flash and 4 in solid or night flash, all while recording 1080p video. That camera is hungry.
What is the RCT715 camera actually for?
Safety. Not highlight reels.
We bought an RCT715 with our own money back in 2022 and ran it for several months before we sat down and reviewed it on our YouTube channel. The first thing we told people still holds. It records 1080p at 30 frames per second with no stabilization. If you are picturing a GoPro on your seatpost, it is not that.
It is a witness, not an action camera.What the RCT715 is for, after months on our own bikes.
What it does well is the job Garmin built it for. It records continuously, and if it detects an incident it locks the footage from before, during and after so it does not get recorded over. You can also set it to record only when the radar sees a vehicle, which saves battery. That mode made the most sense to us on quiet rural roads. In town, something is always back there.
What we learned living with the RCT715
Skip the app for videoPulling clips through the phone app was slow when we tested it. Plug the USB-C cable into your computer instead. The card shows up like a drive and you can scrub through footage fast.
Incident lock is touchyDropping off a couple of curbs was enough to make ours lock the file. Better too sensitive than not at all.
Upgrade the cardIt ships with a 16 GB card, which fills fast with 1080p video. A bigger card means it records over old footage less often.
It is not lightGarmin lists the unit at 147 g. With the mount on, ours came in at just about seven ounces. Fine for commuting and long days. We would not race with it.
One more thing on cameras. Garmin notes that some places regulate or prohibit devices like this, and it is on you to know the rules where you ride. Worth a quick look before you hit record.
Where does bike radar come up short?
Radar tells you something is coming. It does not move the car.
Garmin is upfront that the 820's same-speed tracking can be limited or unavailable at slower speeds, or when the radar cannot read the road because of snow, ice, heavy rain or a bad mount. We ride in the Pacific Northwest, so heavy rain is not a footnote for us. Mount it straight, keep the face clean, and keep your eyes up.
We still would not ride without one. We said it in our 2020 Varia radar post: we feel like we are riding naked without radar. Six years later, that has not changed.
The 820 is the one riders pick. Of all the rear radars we carry, it is the one that goes out the door most often, and the one we recommend most.
The camera still gets asked about. Our 2022 long-term RCT715 review has passed 44,000 views on YouTube.
If you cannot name why you want footage, you want the 820.
Which Varia radar should you buy?
- Varia RearVue 820You want Garmin's most powerful radar, its brightest tail light, and a battery rated for 24 hours in day flash. Long days, group rides, gravel, commuting. If we had to put one radar on most bikes, it would be this one.
- Varia RCT715You want a record of what happens behind you. You commute in heavy traffic, you have had a close call, or you just want proof if it ever comes to that. You are fine charging it after most rides and carrying 147 grams on the seatpost.
Want it under the saddle instead of on the seatpost? The 820 works with the Varia seat rail mount kit. Moving an RCT715 between bikes? Grab a second seat post mount kit. Still picking a head unit to pair it with? Our Edge 550 vs 850 vs 1050 breakdown covers it, and all three work with both radars.
How does the Wahoo TRACKR Radar compare?
We carry the Wahoo TRACKR Radar too. The short version, straight from Garmin's and Wahoo's own spec sheets:
- Cross-brand support. Both use the ANT+ radar standard, so each one works with a Garmin Edge or a Wahoo ELEMNT. The 820's vehicle size, lane change and threat level alerts need a compatible Garmin Edge or the Varia app.
- Range. RearVue 820: up to 175 meters with a 60 degree beam. TRACKR: up to 150 meters with a 35 degree beam.
- Phone alerts. Garmin's Varia app shows ride alerts on your phone. The TRACKR needs a bike computer or watch to alert you.
- Price. The TRACKR is the lower priced of the two.
Light, battery, weight and mounting are all in our full Garmin Varia RearVue 820 vs Wahoo TRACKR Radar comparison.
Common questions
What is the difference between the Garmin Varia RearVue 820 and RCT715?
The RCT715 has a built-in 1080p camera. The RearVue 820 does not, but it has the stronger radar and light: 175 meters of detection against 140, a 60 degree beam against 40, vehicle size and lane change alerts, a brake light, and up to 24 hours of battery in day flash against 6. The 820 weighs 90 grams to the RCT715's 147.
Does the Garmin Varia RearVue 820 have a camera?
No. The RearVue 820 is a radar and tail light. The Varia RCT715 is Garmin's rear radar with a built-in camera.
How long does the Varia RearVue 820 battery last?
Garmin rates it for up to 24 hours in day flash, 15 hours in peloton mode, 10 hours in solid or night flash, and 30 hours in radar-only mode.
How long does the Varia RCT715 battery last?
Garmin rates it for up to 6 hours in day flash and 4 hours in solid or night flash, with the camera recording 1080p video.
How far back can Garmin Varia radar see?
Garmin rates the RearVue 820 to detect vehicles up to 175 meters behind you and the RCT715 up to 140 meters.
Does the Varia RearVue 820 work with the Edge 550, 850 and 1050?
Yes. Garmin lists all three as compatible. With a compatible Edge or the Varia app, the 820 also shows vehicle size, lane changes and threat level.
Not sure which one fits?
Tell us where and how you ride and we will point you at the right one. Both are in stock at the lab and we ship nationwide.
Shop GarminRadar on, eyes up, and wave at the cars that give you room.