New Garmin Varia RearVue 820 Radar Taillight vs. RTL515
Garmin appears to have just absolutely nailed the radar taillight specs on its new Varia RearVue 820, released today.
I love my current Varia RTL515 but have quietly moaned about some of its technical shortcomings- mostly the battery life. Garmin has stopped my moaning. As you can see in the comparison table below, the core specs have been significantly improved across the board.
Enter The Unexpected
I WAS expecting a refreshed Varia early this year and a spec bump to go with it. However, I’m pleasantly surprised to find significant new detection and alert features. Here are the key ones summarised.
- Enhanced Radar: Detects vehicles up to 175 metres away with a wider field of view than previous models, and can identify vehicle size (small, medium, large) and lane changes.
- Improved Visibility: Brightest ever, visible up to 2 km away, with an automatic brake light that alerts others when you’re slowing or stopping.
- Better Alerts: Tracks vehicles travelling at the same speed, provides visual/audible/haptic alerts via compatible devices, and voice alerts on select Garmin smartwatches (in beta).
- Longer Battery: Up to 24 hours in day flash mode.
- More Options: Four light patterns plus custom patterns via the Varia app, and a compact design with a new seatpost mount.
OK I would have bet that Garmin copied the competition with the brake light mode but the ability to detect lane changes and vehicle size is impressive, at least on paper. They also seem to have found a solution to showing vehicles shadowing you at the same speed and maintain a constant distance, something that previous gen radars never picked up.
Comparison: The Old RTL515 vs New VariaVue 820
| Specification | Varia RTL515 | Varia RearVue 820 |
|---|---|---|
| Price | £169.99 | $299.99, 470AUD, €299.99, £259.99 (+£90, +$100ish) |
| Dimensions | 98.6 x 19.7 x 39.6 mm | 98.9 x 25.9 x 43.2 mm |
| Weight | 71.0 g | 90 g (+19g) |
| Light Modes | Solid, peloton, night flash, day flash | Solid, peloton, night flash, day flash, custom mode |
| Lumens (Max) | 65 (Day Flash) | 100 (Day Flash) |
| Battery Life (Solid) | 6 hours | 10 hours |
| Battery Life (Day Flash) | 16 hours | 24 hours (+50%) |
| Battery Life (Radar-Only) | – | 30 hours |
| Visibility Distance | 1.6 km (1 mile) | 2 km |
| Max Detection Range | 140 m | 175 m |
| Radar Beam Width | 40° (55° in reality) | 60° |
| Threat Classification | Speed-based | Speed-, size-, and lateral range-based |
| Water Rating | IPX7 | IPX7 |
| Connectivity | ANT+ (radar/lights), BLE (radar) | ANT+ (radar/lights), BLE (radar/lights) |
| Charging | micro USB (micro-B) | USB-C |
| Replaceable battery | No | Yes (screws on the rear open up the battery area) |
What will happen to the RTL515? RCT715
There are now far too many competitors to the RTL515 at the same or similar price points. Whilst most aren’t quite as good as the Garmin, some are close – like Wahoo TRACKR. That part of the market is only going to get trickier for Garmin who will likely stick with it, discounting RTL515 as needed or perhaps removing it from sale entirely in a few years.
The RTL515 is unlikely to get any of the new features announced today, nor is a direct replacement product likely (with USB-C) at the £100/£130 price point
In short, RTL515 will continue to be offered by Garmin as long as it makes a modest return and there is stock. Garmin has headed on off the road and up the market to a higher price point.
The RCT715 is different. I expect that to be updated by firmware with some (most of?) new features within a few months.
Interesting Design Choices
What stands out most to me is that the light (the red bit) is now at the bottom of the unit rather than the top. This is probably a sensible choice, getting it well out of the way of a large saddlebag. That said, it then depends on where the radar transceiver is located – potentially more critical for safety.
Vehicle size detection comes from the RearVue 820 opting for a new, more precise radar frequency signal (60 GHz v-band, in addition to the existing 24 GHz channel).
As before, this radar can be used with the dedicated Varia mobile app for those who don’t have a bike computer or watch. This can be a great way for your smartphone to announce alerts, for example to earphone (hey, don’t ride with earphones!)
Compatibility is widespread covering many non-Garmin brands. The big HOWEVER is the new features like lane change detection and vehicle size are only compatible with newer Edge models so far like Edge 540 / 840 and Edge 1050.
I’d forgotten about the EU mandating replaceable batteries, so it’s great to see that feature in addition to the also-mandated USB-C. Finally, Varia hits the 21st Century…well, 2026. This will make lots of people very happy.
It’s also worth pointing out the uncertainty around what’s happening with BLE and ANT+ connectivity. Standards fro the former are evolving slowly and, likely, standards for the latter (ANT+) have stopped evolving. Thus, new features like Lane Change might only ever be available within the Garmin ecosystem as a proprietary feature. We’ll have to see how this general issue pans out over the next few years.
Conclusion
The price bump was inevitable. The spec bump was expected. But the New Detection features appear highly impressive on paper.
For me, the improved core specs are all I needed. I don’t think I’ll benefit much from some features like improved visibility, nor from vehicle size detection. However, the ability to detect cars matching my speed is probably going to come in handy many times.
Who’s planning on upgrading at £260 ($300)!
Sources:
- Garmin Product Page https://www.garmin.com/en-GB/p/1689121/pn/010-03180-00/
- Garmin VariaVue 820 Product Manual
- GLLama Youtube. Watch this => https://youtu.be/7K0Od5Qc8wQ
- Garmin Varia seat rail mount kit https://www.garmin.com/en-GB/p/1688821/pn/010-13443-00/
Last Updated on 10 February 2026 by the5krunner
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tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors.
Curious to see how the new alerts overlay will appear on the x40 units (I have an 840). My RTL515 is showing it’s age and the battery doesn’t last nowhere near the initial 16h, maybe 8 or 9.
But the price bump is quite high… nice set of features but still quite a price increase.
it is
yes I do seem to notice the battery decline with radar lights more so than on watches. (Im on my second 515 i think)
i got my 515 in a sale for about £130/$150. Sometimes it was cheaper than that.
Are they discontinuing the 515? If not, I’ll stick with that. This doesn’t offer enough improvements to justify the >50% price increase.
The link to the Beta forum is wrong.
ty i’ll just delete it as its not much use anyway right now
The German version has been castrated once more. No break light, no flash mode and most likely reduced lumen. Because heaven forbids the tail light of a bike is blinking…Nanny State and Lala Land had a baby and called it Germany….makes you wonder if any other country is that stupid.
yes it’s constrained by German (and French) law: https://the5krunner.com/2025/09/25/garmin-varia-light-flash-pattern-ban-extended-in-eu-9-months-on/
Das Auto always wins, but it’s still possible to buy in other European countries that don’t castrate the device and run the risk of enforcement locally.
Given the typical LED headlight flare, I highly doubt anyone would notice.
If they did, comparison to LED rear car running lights will show that the regulation is nonsense in practice. Yes of course most motor vehicles breaking is a bright light show..
Good that they’ve increased the battery life.
I wonder how well it will detect fellow riders, so you can accelerate before they overtake you?
I wondered the same.
Suppose I’ll have to buy one to find out. they are expensive tho!
Now that I’ve bought one, I can confirm that identifying fellow riders is super cool. The icon differentiates them from cars. I can imagine this being attractive to racers in competitions – no more being surprised from behind by a sprinter!
I also think the upgrade in radar performance is worth the price bump. It’s not BS.
@alex, I’m using it with an 840. You get the same options as the 10xx just compressed. I’d post some images if this website let me!
this website lets you! you might have to use html and host the iamge somewhere else. cant recall exactly. if it sdoesnt work send to me and i will edit into your text post
I’m generally quick to upgrade my technology when a better version comes out, but the price increase here is huge and the core functionality remains the same.
At this price point I want video recording.
+1.
I’m still debating this one.
braking and battery life would be good.
Why would they just refresh the Varia RTL515 to a 525 with increased battery, USB-C and some other up to 2026 hardware and sell it at the same price? Nah Garmin is premium brand, so lets add some BS and demand a premium price for it.
So we got some fancy looking things no one ever complained about or asked for and a ridiculous price. Granted braking light is a nice touch but however did we all survive without it before?
Good thing that the premium market is limitless and world population only consists of billionaires.
Here’s to hoping that by the time the battery on my 515 deteriorates Bryton & Co improved.
i thought they would do what you say there…better battery life (didn’t expect it to be quite so good) and then brake light. That would have put them on parity with the competition plus better battery.
i’ve said it a few times here. Garmin is margin drive for share price. Necessarily they have to add these premium components to at least superficially justify the price (even tho no one might use the features much).
it’s obvious in hindsight, I suppose. most things are!! I’m surprised that the technical innovation was able to achieve the new features (testing permittign!)
The drive to innovate is fine for those who can justify the expense on one device, but latter day compatibility is a bad decision, for example new features that only work back to current model minus one takes no account of why we invest in a quality sustainable device.
In other words innovate and do the firmware updates to keep all serviceable models compatible. In this case Edge 1000 – 1050 should have full functionality. Sadly it seems that 1040 was a watershed in a bad way for compatibility. Lost Varia Vision too …