Garmin Varia RTL510 Review (RTL500, UT800)

FTC: Affiliate Disclosure: All links pay commissionReading Time: 13 minutes

Garmin Varia RTL510 Review (RTL500)

I seem to have, once again, waited WAY too long to produce this Garmin Varia RTL510 Review, it must have been out for over a year and a half already. Nevertheless, a review is worth doing as this is a great safety product for MANY kinds of cyclist. Plus, in those immortal words, “Winter Is Coming” and it’s already getting way too dark, way too soon.

NOW is also a good time to talk about Varia as support for it is gradually spreading beyond Garmin Edge devices onto both competing vendor’s bike computers and Garmin watches.

Garmin Varia RTL510 ReviewThe Varia RTL510 is both a smart LIGHT and a smart RADAR. Later in the review, I’ll touch on how it can get EVEN smarter but for now, just know that the smartness manifests itself in the ability to change the light flashing pattern based on vehicle proximity to warn drivers and to provide a visual indication on your handlebars to what is going on behind you. It’s generally great at correctly spotting approaching cars rather than bikes.

In my pre-Varia days, I would say I was generally an alert cyclist who would normally hear a vehicle coming from behind. Varia usually gives you are greater warning time than your ears but I’ve also noticed more recently that those pesky electric cars are so quiet that they can be alongside you before you hear them.

Here is a quick overview with all the gory details further down the page.

Garmin Varia RTL510 Review
  • Price - 80%
  • Apparent Accuracy - 95%
  • Build Quality & Design - 95%
  • Features, Including App - 85%
  • Openness & Compatability - 95%


Garmin Varia RTL510 Review


Garmin’s Varia light and RADAR system work and they work ‘properly’, also providing several personal safety benefits.

The light is bright and the variable flash-patterns respond well to vehicle proximity, alerting the driver of YOUR presence.

The RADAR detection of approaching vehicles works surprisingly well even when there is more than one vehicle. There are rarely false positives and only rarely are vehicles not detected, for example in scenarios where they are moving at the same speed as you.

The integration with compatible watches and cycling computers is mixed in quality, yet improvement in YOUR safety is still delivered in EVERY case and the Garmin Edge + Varia experience is especailly GOOD.

Local links to Amazon, Wiggle, PMC or REI


  • Simple setup
  • Great and mostly accurate warning about multiple, approaching vehicles
  • Battery life is adequate
  • Supported bike computers all present the RADAR information well


  • Price
  • Watch-based Forerunner/Fenix displays on approaching vehicles could be improved
  • Support for SMART LIGHT functions limited to Garmin devices
  • Battery life and charge-up time could be better

OK, now it’s the detailed bit. Please read the whole thing or just skip ahead.

Setup, Contents, Operation & Maintenance

You get the light with compatibility to a Garmin quarter-turn mount. You get one of those mounts too plus a couple of bits of moulded rubber which you MIGHT need in order to mount the rear light to either a round seat-post or aero/wing-shaped seat-post. Finally, there are two black rubber bands to physically attach the mount to the seat posts.

The Varia RTL510 has standard USB charging…you know what to do.

You pair it to a Garmin device in the usual way except, with a Garmin device, it can be paired as both LIGHTS and RADAR, although it seemed to work sensibly for me paired just as RADAR. However, when you also pair to a Garmin as LIGHTS there are further sensor options to allow you to determine, for example, the power on/power down behaviours.

With Hammerhead and Wahoo you can only pair as a single ANT+ sensor. But that’s fine.

There’s only one physical button on the top of the Varia which you press to toggle through the flash modes or press and hold to turn off. Again, it’s typically how these sorts of buttons work so you’ll be able to use it intuitively.

Press the power button again briefly and the status light will flash blue to allow you to pair as a light.

Garmin Varia RTL510 Review

Then you stick it on your seat post, making sure that the light is visible to approaching vehicles and hence the Varia’s RADAR can see them too. Other mounting options are listed further below.

How the RTL510 Works When In Use, When Reviewed

The RADAR detects relatively large objects, like cars, that are closing in on you at over 10km/h from at least 100m away (stated 140m). It also detects two/three cars very well although, for example, if those cars are close to each other the radar can think there is only one. Officially up to 8 vehicles can be detected at any time and I definitely had 4 working well.

  • vehicles pulling out of a junction behind you are, correctly, not detected unless they turn to follow you
  • other cyclists are usually not detected unless closing very quickly
  • vehicles behind you moving further away from you are usually not detected
  • vehicles behind you moving at close to your speed are not detected when in that state – the approach speed must be more than 10km/h, which is probably why approaching cyclists rarely register

When cars are detected, their approximate position is sent as a signal for your device to pick up and display or alert you in an appropriate manner. We’ll come back to that.

Only when the car is close to you will the light’s flash pattern change to become more frequent. All the Varia does in this scenario is to change the flash-pattern of the lights ie any audio or visual alert will be triggered by your handlebar/wrist device (if you have one).

If you have more than one VARIA light (front/rear) then a light network is formed (I only used one rear Varia when preparing this review)

RTL 510 Battery Life, Brightness, Charge & Indication

I’ve not timed how long it takes to fully charge it up but I’d guess more like 90 minutes than 30 minutes from flat to full.

On a full charge, the battery life is up to 15 hours of usage when the intermittent flashing mode is selected. I’ve had well over 10 hours, so the stated figure could well be right. Though remember that you may be often using this as a RADAR and so you will have day-time usage as well as night-time usage and so those 15 hours of charge can be eaten up more quickly than you might imagine.

The status light indicates the charge state when charging, so a flashing green light indicates charging and a solid green light indicates a full charge. It’s also BLUE when available to pair as a LIGHT

Garmin Varia RTL510 Review
Status Light


The Garmin Varia RTL510 Ecosystem – Reviewed

The RTL510 works well as a standalone smart rear light. At well over £/$/Eu100 it’s very expensive just for that purpose, so its value is better justified as part of your wider safety ‘ecosystem’. Having said that, the generic rear standalone RADAR light must be THE most effective anti-accident gadget there is. But let’s just briefly cover what else can link in with the RTL510 in your safety ‘ecosystem’

Broadly the other components fall into the categories of alerting devices (audio/visual), other lights and control devices. Older devices are also supported and the current Garmin accessory range comprises these



Alerting Devices: Bike Computers and Wrist Watches

In simple terms…the Varia RTL510 commonly links to your Garmin Edge to give on-screen warnings.

However, the Varia system is also supported by cycling computers such as those made by Wahoo ELEMNT, Hammerhead Karoo, Pioneer, Stages Dash (soon, maybe) and other Garmin devices like some Forerunner/Fenix wristwatches. So, as you can see from the following image, I did a bit of testing over several devices and I’ll share my experiences on each device later in this review.


Edit: As of December 2019 Stages Dash L50/M50 also support Varia

Stages Dash L50 Garmin Varia RTL510


Display Devices: Alternative Alerting Devices

The Varia Vision heads-up display (HUD) is also a display option and so is the Varia Handlebar Display (not tested)

An audio-visual warning can also come from a Varia Handlebar display unit which might be a sensible addition for you if you don’t yet have a compatible bike computer. The handlebar display comes in the RTL511 bundle (not 510) for about £/$/Eu50ish extra at RRP, which is cheaper than upgrading or buying a new bike computer. I’d buy a new bike computer but buying new tech is my response to most first-world problems 😉

Other Lights

Naturally, front lights are also supported which currently include the latest, greatest, brightest Varia T800 (GoPro mounted) and the older, twist-mounted Varia Smart Bike Light

There are other rear-light/RADAR options too. For example, the Varia RTL500 is an earlier version of the RTL510 and has several smaller red LEDs rather than one large one. That’s perfectly fine to buy too. Indeed, in some ways, I prefer the light-flash patterns of the RTL500, it’s just that the RTL510 looks sweeter 😉

Garmin Edge 820 Varia RTL 500
Garmin Edge 820 Varia RTL 500

Control Devices

Varia Remote

The Varia remote can adjust brightness as well as indicating left/right if you have two rear lights.

I didn’t test the Varia Remote at all as part of this Garmin Varia RTL510 Review. However, some CIQ apps for the higher-end Garmin devices do start to take over some of the in-ride control functionalities that the Varia Remote provides. These are the 3 most popular CIQ apps.



Source: VARIA on Garmin app store.

  • Tail Light Data Field (TLDF) – On a touchscreen Edge device you can tap the data field to save battery by turning off/on the rear light. The developer, Camillo, has added a neat new feature which records the status of the light in the FIT file thus making it possible to track back and potentially find a light that was dislodged from your bike and lost.
  • Radar Light – Similar to TLDF and also works on non-touchscreen devices, so the Forerunner now comes in to play in this category. Here you can also control the light modes and show the battery status. Apparently, it supports multiple rear lights.
  • Radar Battery – Displays the battery status as a coloured data field also showing the percentage.

Essentially these CIQ apps make more accessible some of the sensor options that are otherwise squirrelled away in Garmin’s labyrinthine menu systems.

Working with Bike Computers – Garmin Varia RTL510 Review

There’s quite a lot to talk about here so I’m just going to focus now on the rearview radar and the integration with bike computers and GPS sports watches. Let’s start with Garmin watches…


Garmin Varia RTL510 with Garmin Forerunner / Fenix / Vivoactive Watches

Precise models supported here


The experience on the Forerunner is adequate.

You can see on the image above that there is colour coding to indicate the level of proximity and a little white dot represents a vehicle. That’s fine but the watch is typically on your wrist and relatively far away from your line of sight and when that’s coupled with a necessarily small screen then the whole watch face experience is somewhat crowded and peripheral. ie the vehicle proximity information is LESS actionable because of the watch position and size.

Set against that, however, are the beeps and vibrate alerts which work well on your wrist to attract your attention at appropriate times. If you turned off those alerts and only wanted to rely on the visuals then a Forerunner on your wrist wouldn’t be that useful (maybe it would be if it was on your handlebars).

If you are in the situation of owning a Forerunner/Fenix/Vivoactive and thinking of getting a Varia then, don’t worry, it IS a good enough experience and will add to your overall safety.

Garmin Varia RTL510 with Garmin Edge Devices

You can see, in the top right corner of the image below, the WiFi icon showing that the Varia is connected and ready-to-go, when it’s red…guess what? it’s NOT ready-to-go.



The experience with the Garmin Edge devices is good. Even with the smaller 820/520, you get a MUCH better experience compared to that from the wristwatches. The visual alerts are just that little bit clearer and, I think, aesthetically well integrated to the screen. Note how some of the red on the Edge, above, is displayed transparently and so it does not waste valuable screen real estate. (Contrast that with Wahoo’s and Hammerhead’s implementations in the subsequent sections)

There’s no real downside. Buy one.

Here are some pretty rubbish images but they give you a flavour of all the configuration options and messages shown on an edge, there might be an option somewhere in there that I’ve forgot to cover in the main review.


Garmin Varia RTL510 with the Hammerhead Karoo

Karoo-flavoured Varia is just about perfect but…


This is a beautiful and clear link-up between Garmin Varia and the Karoo. Even the little cars could have been tacky but, IMHO, are pretty cool in the way they have been implemented

You get 4 levels of alert-coloured bar: RED=close proximity warning; YELLOW general warning; GREEN warning cleared; WHITE no warning.

You can also just about see, in the top left corner, the togglable bicycle icon showing that the Varia is connected (yes togglable IS a word…I checked)

The Karoo implementation is just about perfect.


The Karoo has no audio. Which is a BIG issue for some of you I believe? You would have to have BLE helmet speakers or a BLE handlebar speaker paired up to the Karoo to get the audio alerts (should work but not tested). You don’t get the full range of configurable RADAR/LIGHT options offered on the Edges but that’s no massive loss.

Trying to be positive, if you are in an urban area the frequent audio alerts are VERY annoying and I would turn them off in any case. So the Karoo would be OK there (maybe!)

Garmin Varia RTL510 with Wahoo ELEMNT /ROAM/BOLT

Not as sexy-looking as the Karoo but at least you can hear it


Wahoo is pretty cool too. I don’t have the colour-screened Wahoo ROAM model anymore but I have seen Varia working with ROAM and it is slightly prettier. The greyscale implementation of Varia on the base ELEMNT and Wahoo ELEMNT BOLT is still good though. Unlike the Edge devices, you do lose a bit of screen at the side but I didn’t find that a problem at all. The little car icon is also not quite as cool as on the Karoo – maybe it’s a Ford rather than a Tesla. But the ELEMNT does the job…and that is what the ELEMNT is 100% designed to do all over.

The big plus with Wahoo is that you can additionally set the top/side LEDs to flash when an alert is triggered. That works well but can get a bit annoying in busy traffic.

The Wahoos have no specific ‘Varia connected’ icon on the main screens but you are VERY clearly in large text warned of a low battery or disconnected device.

Here are some more images which don’t fit anywhere special by themselves. Enjoy.


Other differences across the manufacturers

You should pair the RTL500 as both a LIGHT and a RADAR as each sensor pairing gives you different options. However, that’s only possible on a Garmin watch/computer, so these points won’t apply to every device you use the Varia with.

  • Alerts – Only the Forerunner has a vibrating alert, it’s the only one that touches your skin so that makes sense. For some reason, a frequent vibrate annoys me less than a frequent, audible alert.
  • Muting – you can mute the alerts on all the bike computers
    • With the Karoo it’s super-simple and you just tap the bike icon in the top left of the screen and this also then entirely hides the RADAR bar from the left just leaving the small bike icon that can be tapped again to be re-enabled
    • With the Wahoo, muting the RADAR is not easy as you have to disable it within the ANT+ pairing menu. That’s fine for a more permanent change to the setting but a real PITA mid-ride.
    • Garmin similarly difficult as Wahoo through the main menus where the device can be disabled. However, the pull-down menus of the Edges does make it a LITTLE bit easier (See CIQ apps later for superior workarounds to this)
  • Extra Info – is generally available at the place where you have paired the Varia LIGHT/RADAR. However, the information and options on the Edge devices can also be accessed from the pull-down menus at the top of the screen which shows battery status, light testing options, and more
  • Extra options – On the Edge, you can determine when the auto beam on occurs (Timer Start, or Edge Turn On) and what light mode should be used (Auto, Trail, Individual, High Visibility).

Garmin Varia – Typical Customer

This is a great product as it should appeal to any cyclist who’d prefer not to be hit by a car. Which, let’s face it, is most of us.

However, there are some nuances

  • Automatically changing rear light patterns, based on proximity, are going to be useful to most cyclists. But the Varia system also supports indicator lights which will also be particularly useful to commuters faced with the need to signal to a large number of vehicles on each journey.
  • Conversely, the Sunday cyclist might also be interested in a visual or audible warning of approaching cars on narrow, wet and slippery country lanes
  • The whole system that includes handlebar remote controls is perhaps going to appeal more to less confident, urban cyclist or someone who just likes to have all the gadgets.
  • Perhaps Varia is a ‘must-have’, purchased by a concerned parent for the youngster’s first independent bike?

Anyway, the common theme for all types of buyer is ACCIDENT AVOIDANCE coupled with compliance to road safety laws.

Garmin Varia RTL510 Specifications

  • Modes: solid, night flash, day flash (RTL511 only has solid mode)
  • Battery Life – Up to 15 hours (6 hours solid, 6 hours night flash, 15 hours day flash) RTL511 has 10 hours of solid only
  • Lumens: 20lm solid, 29lm night-flash, 65lm day-flash (Contrast to Bontrager Flare R – 65 Lumens with 2km visibility. 270-degree angle – see below) RTL511 is 7lm
  • Dimensions: 98.6 x 19.7 x 39.6 mm
  • Weight: 71.0 g
  • Visibility – 1 mile
  • Side visibility? – Yes
  • The angle of light visibility – 220 degrees
  • RADAR Angle – 40 degrees
  • Communications – ANT+ only, no BLE
  • Vehicle detection – 140m/150yards
  • Compatability – Garmin Edge, some Garmin Forerunner, Hammerhead Karoo, Wahoo ELEMNT (check
  • Water rating: IPX7
  • RADAR detects 8 vehicles
  • Approach speed detection – 10 to 160 km/h (from 6 to 99 mph)
  • Manual: here
  • Latest Firmware I used: v3.50 (firmware notes and history HERE)
  • Alternative mounts eg saddle/saddle-bag mounts: Check

Garmin Varia RTL510 Review – The Future

I would like to see the Varia lights and RADAR adopted more widely by other manufacturers. For this to happen, IMHO, Garmin needs to make a cheaper version and more, competing bike computer makers need to add support…Sigma, Bryton, Lezyne, Mio Cyclo, etc..

I don’t see a significant need to change the RTL510 itself. Perhaps different light-flashing patterns could be introduced to prolong the battery and/or a larger battery introduced. BLE support might add the ability to connect to smartphone apps and open up a new market for Garmin.

It would be great to enable group riders’ Varia lights & Radar to work together and co-ordinate flashing patterns to further aid the group’s visibility. Also for group members who do not have a Varia device to also be able to receive proximity alerts. But I don’t think any of that is quite possible as things stand in Nov 2019 (please let me know if that’s wrong, I’ve not had a definitive answer to that)

Perhaps an alert too far would be for Garmin’s in-car devices to be forewarned of cyclists’ presence either as the driver approaches the cyclist from behind or if the cyclist is undertaking in slow-moving traffic (filtering…it’s NOT against the UK Highway Code). Or perhaps even a global standard to make car’s SATNAVs respond to ‘I’m HERE’ signals from cyclists devices…ain’t gonna happen 🙁

Perhaps the more advanced Dura-Ace Di2 shifter buttons could be used as an indicator if there are two rear lights? Let me know, that MIGHT already be possible via some wizardry in CIQ (but I think NOT)

Prices, Discounts & Availability – Garmin Varia RTL510 Review

Garmin Varia items are now available widely at discounted prices and it’s worth shopping around. The links in the post all click through to give you a choice of retailers for your country and should also click through to show you all the Varia products.

The discounts do all seem similar across different retailers, so I’d imagine Garmin is encouraging uniformity in some way. You might get seasonal/Black Friday discounts on one of these.

Currently, the standalone RTL510 is £130 – Eu155 – US$200

The blue images above/below click through to show prices from several of your local retailers.

NB: Some bundles come with the TL300 rear light (RTL is RADAR, so TL has no RADAR)


Reader-Powered Content

This content is not sponsored. It's mostly me behind the labour of love which is this site, meaning it's entirely reader-powered content ❤️ I'd really appreciate it if you'd follow, subscribe or Buy Me A Coffee ❤️ Alternatively please buy the reviewed product from my partners (which costs you no extra) and, for that, I receive a small commission. Thank you! FTC: Affiliate Disclosure: All links pay commission. As an Amazon Associate I earn from qualifying purchases.

9 thoughts on “Garmin Varia RTL510 Review (RTL500, UT800)

  1. I have one and love it! A product that just works without much of a learning curve.

    The driving in lower Fairfield County Connecticut is very aggressive, with plenty of tailgating, close passes even around curves across the double yellow line, and drag racing to make right turns (despite the complaining, you guys in the UK have it way better than we do). It can be a trying experience. With the Varia, I can see how many cars are behind me and how close they are, which allows me to better focus on avoiding potholes and giving runners a wide berth.

  2. According to the spec, the 511 model has only the solid mode. No day/night flash. Is this to be understood that the solid mode still includes flash patterns when a car is approaching? Or solid means solid that is it?

      1. That’s correct. The RTL511 is for German market, and due to very strict regulations in Germany, no flashing lights on bikes are allowed, and brightness is limited, too. So the RTL511 is either solid or off.

  3. had them on sale last week. Since then, I owned not one, but two (because there were two RTL 510 in the box, but only on mount and one o-ring, but non of the adaptors. I don’t believe it was a new box. Its pretty common now at amazon to get used stuff. But, both where working and I sold the second one für 100€, the one mount was enough for my bike.

    Do you switch them off at the switch or let them sleep (im using my bike mostly for daily stuff and commuting)? My old bike light had a daylight and a movement sensor and switched on accordingly.

Leave a Reply

Your email address will not be published. Required fields are marked *