The new Garmin Varia RTL510 is a product I never knew I needed. It’s an early warning detection system that lets you know a car is approaching from behind, which is a godsend on the rural roads I regular ride; it also syncs perfectly with a Garmin Edge (no surprise there) and is a very bright rear light.
- Pros: Early warning detection, syncs seamlessly with Edge computers, bright light, easy mounting, sleek looks
- Cons: Expensive
A few years ago Garmin launched the Varia radar system, a rear-facing radar device that linked to a handlebar unit to warn of approaching cars, their proximity and speed of approach. I’ll be honest and didn’t really think much of it. I mean, what’s wrong with looking over your shoulder?
> Garmin launches new Varia radar system + remote controlled lighting
But I’m open-minded and happy to try new things, so I was intrigued to try the newly updated Varia RTL510, which combines the radar technology with the light tech from Garmin’s Varia rear lights. I’ve been increasingly running daytime rear lights so this seemed like the ideal product for me.

And I have to admit I’ve been really impressed. I won’t go as far as saying it’s one of those products that I ever wondered how I coped without, but it’s not far off. Let’s be clear, it doesn’t replace your own senses when it comes to being alert to other road users, and it’s arguably not going to make you safer. But what it does and what impresses me is that it detects an approaching car far sooner than I would.
The range of detection is 140 metres and every time I’ve looked over my shoulder after first being warned of an approaching car, I’ve been surprised by just how far away the car is.
So it does act as a really useful early warning system, and for riding the quiet country roads that I do on a daily basis, I like that.
Heads up
The Varia RTL510 can be synced to a dedicated radar display unit, or it can be paired with a Garmin Edge computer. I’ve been doing the latter, testing it with an Edge 820 and more recently the new Edge 130 (review to come). You can view all compatible devices here.
Pairing the Varia RTL510 to the Edge is a doddle: you simply connect it as a new sensor via ANT+. That’s all you have to do. You know it’s connected because you have a small radar symbol in the top corner. The Edge can also connect to the light and switch it on and off automatically when you turn the Edge computer on and off, which is pretty neat.
Fitting the Varia to the bike is also simple. The mounting bracket attaches using a rubber band – there are two different rubber adapters to suit round and aero seatpost – and the same quarter-turn interface as the computers fixes the Varia in place.

It’s a vertical design and is fairly unobtrusive on the bike. It’s not much bigger than other lights on the market and it’s a fairly sleek design.

Then you go ride your bike. The first warning you get of an approaching car is a beep. After that, a thin column appears on the side of the screen (you can customise which side of the screen it appears on), with a dot at the bottom representing the car and position relative to yours, represented by that small radar logo in the top corner. The colour of the column indicates the speed of the car: amber is standard and red light means to take care, a car is approaching at high speed.
I was asked a question on Instagram along the lines of ‘great idea, but surely it trades one risk for another?’ It’s a really good question. What I’ve found is that the warning beep is the best part of the system, and rather than constantly looking down at the screen, I just make occasional and quick glances to see where the car is.
Be warned
Why the Varia appeals, and why I’ve taken to using it for every ride, is because I’m happy to admit there have been occasions when I’ve been surprised by a car passing me, simply because I’ve been deep in thought or just let my mind wander, or because it’s really windy and your hearing is impaired. That surprise factor hasn’t happened once with the Varia.
So that warning beep serves a very useful purpose. As a result, I’ve found I’m not checking over my shoulder ‘just in case there’s a car approaching’ as much as I used to. You shouldn’t depend on the Varia completely, but you pretty much can. What you can’t see is that the Varia light blinks when a car is overtaking you to serve as an additional warning to the motorist.
After that beep occurs, it’s easy to quickly glance at the computer screen to see where the car is in relation to your position, but that element is secondary in my opinion to the early warning beep. It is useful when it shows two cars on the screen, the maximum it can display.
Rear light
The other bonus is the extremely bright 60-lumen rear light that is incorporated into the unit. It has a claimed visibility range of one mile and has a run-time of 15 hours in flashing mode or 6 hours in solid and night flash mode. The light also has a 220-degree range to provide some side-on visibility and means car drivers should see the light before the radar sees them.

The Varia is easily charged via a USB port and the Edge serves up a low battery warning which is useful.
City limits
It works really well on country roads where traffic is light. Riding through towns reveals it can be triggered by parked cars which does reduce its usefulness to a degree, and I’m not sure given the hustle and bustle of busier towns that it would be as useful – when you’ve got a constant stream of cars passing, you don’t need to know there’s a car 140 metres away.
But if your commute or ride starts in the city and takes you out into quiet country roads, as most weekend cycle rides likely do, then it’s a useful addition. It could also stop you being caught unawares by near-silent electric cars.
What about when you cycle with other cyclists? I’ve used it both in a chain gang and club run and both times it wasn’t fooled by the cyclists following in my wake, yet was still able to detect a car approaching our small group. So it works well in those circumstances as well.
Warning or camera?
There’s no denying it’s a pricey investment. You are getting a rear light as well, although even a normally expensive rear light such as the Exposure Blaze Mk1 Daybright is still cheaper at £90. But there is nothing else like the Varia on the market – the only vaguely similar product could be the Cycliq Fly6, a £175 rear light with an integrated camera.
Choosing between the two comes down to whether you prefer to film close passes or have an early warning system, and much of that probably comes down to how busy the roads are that you regularly ride.
Obviously, the Varia isn’t going to prevent a close pass or a car hitting you. But if you’re riding along a quiet country road and a car comes out of nowhere at speed (as happens frequently in the Cotswolds) then it does give you that warning. What you do about it is up to you, but knowing there’s a car approaching often before you actually hear it is a positive thing.
I know I will cope just fine when Garmin asks for the Varia back, but having ridden with it for several weeks I’ve really got used to the early warning system. Would I part with £170 for it? I’m not sure I could… But if price is no obstacle then it’s a no-brainer and I’d tell you to go out and buy one.
Verdict
Useful early warning system with a bright rear light, but quite pricey
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road.cc test report
Make and model: Garmin Varia RTL510
Size tested: n/a
Tell us what the light is for
Garmin says, “Ride smarter and more aware with Varia™ RTL510 rear-view radar. Mounted neatly on the seat post, it provides visible and audible alerts for vehicles approaching from behind up to 140 metres (153 yards) away. Plus, the bright tail light is visible in daylight from up to 1.6 km (1 mile) away, so you can ride with confidence and peace of mind.
This sensor has your back
While out on a ride, you have to keep track of everything. What’s your route, how far you’re going, how fast and how hard you’re going to push it. But with Varia radar along for the ride, it’s like having eyes in the back of your helmet. It’s essentially an early warning system so you see cars approaching from behind and they see you.
This sensor has your back
Safety in numbers
Varia™ RTL510 rear-view radar is just one part of cycling awareness. When paired with compatible Garmin devices the system helps to create safer riding conditions by alerting riders to vehicles approaching from behind. Green light? All good. Amber light? A vehicle is approaching. Red light? Take care – a vehicle is approaching at high speed. Ride safe.”
Tell us some more about the technical aspects of the light?
From Garmin:
Provides visual and audible alerts to warn of vehicles approaching from behind up to 140 metres (153 yards) away
Tail light offers daylight visibility up to a 1.6 km (1 mile) away and is visible within a 220-degree range, so drivers can see you well before the radar sees the vehicle
Sleek vertical design easily mounts to most road-use bicycles, including racing, touring and commuter styles
Requires a dedicated radar display unit (sold separately) or wirelessly integrates with compatible Garmin devices1
Battery life: up to 15 hours in flashing mode or 6 hours in solid or night flash mode
It’s a doddle to use, there’s just one button on the unit itself.
The clamping system provides a secure connection to the seatpost and it doesn’t shake or rattle about, even on off-road trails.
It hasn’t rained in ages, but I subjected it to the hosepipe test and it was just fine.
I got pretty close to the claimed 15 hours – that’s likely more than enough for a week’s worth of riding for most people.
Really impressed with the performance as an early warning system.
Early days but so far, so good.
It doesn’t add much weight to the bike at all.
This is a tricky one. It’s expensive yes, but there are no rivals on the market and it occupies a real niche. I think if you like the safety appeal of the Varia you might just be able to justify the price.
Tell us how the light performed overall when used for its designed purpose
The light is bright with a good 220-degree range.
Tell us what you particularly liked about the light
Bright and it blinks when a car passes you.
Tell us what you particularly disliked about the light
More side-on visibility perhaps.
Did you enjoy using the light? Yes
Would you consider buying the light? Yes
Would you recommend the light to a friend? Yes
Use this box to explain your overall score
It’s an expensive but really useful product especially if you mainly cycle on rural roads.
About the tester
Age: 31 Height: 180cm Weight: 67kg
I usually ride: My best bike is:
I’ve been riding for: 10-20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, touring, mountain biking









48 thoughts on “Garmin Varia RTL510”
For that money, I’d want a
For that money, I’d want a camera.
I just had my old Fly6 give up the ghost, so I ended up buying a new Fly6CE model. The mounting is much better, but the buttons are surprisingly difficult to press. However, it does exactly what I want for a rear light and camera.
(I’m now trying to replace the battery on my broken Fly6, but haven’t succeeded yet. Pro-tip – never try to solder a Lithium-ion battery unless you know what you’re doing).
hawkinspeter wrote:
Did the fire brigade arrive in time
?
StraelGuy wrote:
Luckily I found this info before I tried: https://medium.com/@bikebot/fly-6-battery-replacement-cdbcd09150ce
I got some of the conductive glue, but so far it’s not working. I’ll give it another try with the same 18650 and maybe use something to hold it steady while the glue dries to see if that gets it working and if that fails, I might try to find a 18650 with metal tags already fitted.
I’ve had one for a couple of
I’ve had one for a couple of years now and wouldn’t leave the house without it. 140 meters is usually enough, it will allow you to claim the center of the carriageway to signal they don’t really have enough space to pass you at that next traffic island, hopefully causing them to brake or get round you quicker than the island. I also regularly move out from my line and back in just to give the driver another visual “cue” that I’m there (not that you should miss me, but I’m specifically trying to appeal to the visual receptors at the periphery in case they’re distracted) – I also hope they’ll think me a “untrustworthy” rider, incapble of holding my line, and give me more room when they pass. The suprising one is to know you’re not being followed on a descent, which I always thought I was (due to the wind noise) but would be going too fast to check over my shoulder.
In short, if you ride roads by yourself, I’d say its worth having.
I agree. I’ve had the radar
I agree. I’ve had the radar only without the light. I can honestly say it’s the best purchase I’ve ever made for my bike without exception. It is true that nothing replaces your senses, but I’m happy to accept a helping hand for all the reasons you stated..
if you’re unsure, just buy one. I’m glad I did.
Tempting, as all my riding is
Tempting, as all my riding is rural. Can it be run in radar-only mode? I’ve got a Seesense Ace on the way which appears to be a smarter light than this (and lower profile).
kil0ran wrote:
On the one I have you can adjust the light function from your Edge.
Yay, yet another source of
Yay, yet another source of irritating bleeping noises. Just what the world needs.
Interested to hear how well
Interested to hear how well it works with the Edge 130 – is the bleep loud and does the on-screen indicator work in the same way?
kil0ran wrote:
I can confirm it does – just started testing the 130 and it works just fine with the Varia
Typical Garmin – high price
Typical Garmin – high price for low tech. I had the first version, battery life was laughable. Sold my Garmin Edge (Garbage) and then the Varia. It only works with Garmin of course!
Now, instead I got the very small, but very powerful Exposure Trace daybright pack (front and rear) plus a mirror at the end of my handlebar. These lights are amazing. Since using them I have not had one car in 1½ years pass me close by.
And, actually I believe its much more important to have a strong FRONT light. Many more accidents happen from the front – oncoming cars making a turn in front of you, cars coming from side streets, pedestrians etc.
I have the older version.
I have the older version. Super bright and in flashing mode the type of rear light that really annoys fellow cyclists on the Dunwich Dynamo.
NIce that the new design is more vertical. The old one is a bit of a pain to position on the seat post for those of us with large thighs. On that subject, the Garmin mounts supplied are pretty focussed on seat post positioning which assumes that we all have a lot of exposed seat post, no saddle packs, racktop bags, etc. For my tourer, the great folks at 76Projects came up with a Garmin mount that fitted securely to the rear of the pannier rack.
But a great shame the new model seems to have lost the automatic brightness/flash adjustment that the old one uses when it detects a car approaching – which made it a great daytime rear light even without the Garmin computer.
Upgraded from the version 1
Upgraded from the version 1 to this version a few months back – I think they’re great, just improves your situation awareness and takes away the ‘drifting away’ factor you get once you’ve been out on a long one. It’s the perfect example of a product you never knew you needed until you tried it.
I have an RTL510 that I pair
I have an RTL510 that I pair with an Edge 1030. I can’t hear the 510 warning beeps 95% of the time. I can sometime hear a faint beep when riding slowly on a really quiet road. There isn’t any volume or tone control for alerts on the Edge 1030 or any other Edge computer. So if you have some high frequency hearing problems/loss you probably won’t be able to hear the alerts. You wonder who really tests these things?
jmess wrote:
Interesting. I’ve only used turn-by-turn once on my 130 and thought the beeps were a bit quiet so if there’s no volume control for the beeps generated by the RTL510 I wonder if it’s going work for me.
I agree about testing and also market awareness. Late 40s now so I’m in the world of varifocals and a lot of these screens just aren’t designed for that.
Exactly what am I supposed to
Exactly what am I supposed to be doing thanks to the extra data from this thing that I’m not doing already riding to the road conditions?
At best it’s yet another cycling gadget masquerading as a safety tool, at worst in 5 years we’ll all be forced to use them by people that don’t cycle.
Prosper0 wrote:
My thoughts too.
The only reason I’d have one of these is if the warning given by them was loudly given inside the following car. But that won’t happen as it’s obviously an attack on motorists freedoms.
Prosper0 wrote:
If you don’t hear the car due to them being electric, wind noise etc. then you won’t have the “data”, the way I see it is that it is like somebody coming behind you and shouting BOO, you jump out of your skin, but if you knew they were there, when they said BOO you don’t, it is all about knowing you are going to be overtaken, the exact same reason when in a group ride riders shout Car Up/Down, it is all about awareness, which is all about safety.
mikeprytherch wrote:
But it isn’t a surprise, is it?
As a cyclist on a road, it’s 100% fact that, at some point, you are going to be passed by a faster vehicle, regardless of whether you heard them coming, or not.
LastBoyScout wrote:
Absolutely we all know at some point we are going to be overtaken, it is nice to know when it is going to occur not, that is the bit you don’t always know unless you only ride in the city with constant traffic, on country roads it can be infrequent.
mikeprytherch wrote:
But if you’re going to be overtaken then the data is irrelevant.
What you need is some kind of minority report like pre-crime device that tells you if they’re going to hit you, preferably with gesture support for close passers.
aegisdesign wrote:
Not sure I follow… how is knowing how many vehicles are approaching and their closing rates irrelevant ? I mean you can always keep looking around to confirm all this, but having some situational information available without requiring that surely makes planning easier and the amount of ‘not actually looking in the direction of travel’ somewhat less. It’s pricey, for sure, but sounds like something that could be useful.
fukawitribe wrote:
Does knowing that prevent you from being hit? I would argue, it doesn’t. So if it doesn’t prevent you from being hit, it doesn’t matter if you know. It’s irrelevant data.
Planning for what? To dive out of the way should a car come up behind you with a driver who is a psychopath intent on running you off the road? Is that a likely occurance?
aegisdesign wrote:
It doesn’t absolutely prevent you from being hit, and no-one is pretending it does – nothing does – but some people may think’s it useful – do you not understand that ? Did you read/watch Rays review ? If you do, fair play, come back and say why you think it’s irrelevant.
I’m unsure how to deal with this – I meant ‘plan’ in the normal way we always we decide what we’re about to do on the road (or elsewhere) whether on a push bike, a motorbike, in a car or whatever – what do you mean ?
fukawitribe wrote:
No. I don’t understand why some people may think it’s useful. It gives you information you can do nothing about. How is that useful?
But I don’t plan to do anything about a car behind me other than when turning right where I’d look anyway.
As you’re riding along a road what are you planning to do with the information that a car is about to pass you that is different to if you were blissfully unaware of it? The implication is that you’re responsible for some action prompted by the car behind which is utter nonsense – it’s the responsibility of the vehicle behind not to hit you.
aegisdesign wrote:
So a number of people who use this bit of kit, find it useful and explain why, but you don’t understand. I suggest you don’t buy it; it’s clearly not for you 🙂
It is the responsibility of
It is the responsibility of the overtaking vehicle. But if they hit me, that doesn’t help.
What I do when being overtaken is move over at the last minute. That turns a ‘close pass’ into a wider pass.
Other things I do ‘with this data’:
-stop riding next to my friend.
-look ahead, if there is oncoming traffic, consider slowing down or pulling onto the verge to avoid being squeezed by a car passing when there is a car coming from the other direction
-hold a steadier grip on the bar, not grab a bottle etc etc.
mikeprytherch wrote:
Double post
To people wondering what to
To people wondering what to do with this information, at low volume roads that especially when I am very slow such as uphills or when tired, you may do the wobble dance: pretend to woble as if you learned yesterday how to cycle. It will consume around 20cm of road space but it will give you more that 50cm of extra passing distance. Just try it.
Useful when turning right. It
Useful when turning right. It’s sometimes difficult to take in fast approaching cars with a quick glance over the shoulder.
What if you don’t have an
What if you don’t have an Edge computer – does it come with it’s own display?
If not, then it’s not £170, is it? It’s £170 PLUS another few £100 for something to see the information.
Edit – just looked and it’s £260 with a display unit!
I had to give up cycling for
I had to give up cycling for over 20 years due to ill health and missed the recent cycling boom. One of the things I don’t understand with the new breed of cyclist is their near obsession with what is approching from behind. Just ride a decent distance from the kerb and worry about the idiots pulling out in front of you. They are far more likely to cause you injury.
Surely this is completely
Surely this is completely useless in a busy town/city where there are always cars around you in close proximity.
MarkiMark wrote:
You didn’t read the review then?
I’ve got the earlier version
I’ve got the earlier version of this. I find it a really useful bit of kit as being slightly hearing impaired I don’t always pick up on approaching traffic; this sends a signal to my 520 and flashes up invariably catching the eye and providing some forewarning of upcoming traffic. When riding with a guy who has had a stroke the other week we realised it may also be a help where people have issues with mobility in their neck/shoulders. I wouldn’t be without it now; plus it’s a laugh when I shout car up when no one else has seen or heard anything 🙂
This is an over-engineered
This is an over-engineered solution to a problem that has already been solved … a simple mirror works much better and lets you see exactly what is behind you.
nbrus wrote:
Others who have tried it may differ in their opinion
https://www.dcrainmaker.com/2018/04/garmin-varia-rtl510-radar-cycling-light-in-depth-review.html
I have the old model and love
I have the old model and love it.
Wasn’t sure before I got it if was worth it, but for me it is.
It’s great when I’m out in the country roads; a little bleep lets me know a car or whatever is coming so I can cycle suitably.
secondly when I want to pull out to the centre of a busy road I have an idea when I can as I can see the gap on my Garmin, ( I find it uncomfortable looking over my shoulder, so with this I have a better idea when to look to double check as I would not pull over without looking).
Also handy to know how many cars are behind you, but this depends on the layout of the road etc.
Also if the changing flash patterns work when a car approaches all the better.
Would I recommend them to most people? YES
They do have their faults as well though but the positive easily out ways them.
Having attended a fatality
Having attended a fatality where a crucial factor was one rider blindly following another crossing from their carriageway whilst attempting to access a cycle path on the other side of the road and being hit from behind by a car at speed (but not speeding) then yes I can see that something like this has a place.
I am also often unaware of a vehicle behind as soon as I would like to be due to wind noise and failing hearing. With the increase in quiet electric vehicles and a reluctance to use a courtesy beep by many drivers afraid of annoying a “lycra lout” this is only going to become more frequent. Whilst knowledge of a following vehicle may change nothing about how I am riding or road positioning, I would rather know they are there.
I particularly like the idea of the light doing something on detection of an approaching vehicle, like coming on, or brightening in daylight / dimming at night, interacting with vehicle alert systems, changing flash mode or otherwise doing something based on driver psychology to attract attention to itself. If combined with a camera it could turn the camera on, or turn it to super hi res mode or snapshot a numberplate or any other number of situation relevant actions.
Technology should not replace basic roadcraft on behalf of either rider or driver, but I’d probably buy into this type of device, just not this one. Maybe Cycliq are looking for a new feature for an upcoming Fly 6 model? Camera, proximity warning and light in a single package?
Mungecrundle wrote:
I’d recommend a small mirror (Cateye BM45 is the best – https://www.tredz.co.uk/.Cateye-BM45-Bar-End-Mirrors_84534.htm ) for easily having a quick check behind you without having to move your head. Once you get used to it, a quick glance gives you a good idea of what’s behind you and if it looks clear, you can do a proper check behind in case of blind spots. It’s a lot cheaper than a radar and gives you more information about what’s following you.
Electronics can go faulty and
Electronics can go faulty and fail to work if the battery runs down, but a mirror will always show you what is behind. This radar solution reminds me of how NASA spent millions developing a pen that would write in space, while the Russians used pencils!
nbrus wrote:
Don’t want to spoil your arguement, but the NASA story is a myth. (And in fact pencils created an issue where the tips would flake letting conductive microparticles float around.) NASA didn’t spend anything developing the Space Pen:
https://www.scientificamerican.com/article/fact-or-fiction-nasa-spen/
I’d rather use all that space
I’d rather use all that space on my seat post for my saddle pack holding multitool, 2 tubes, tyre levers and split link (and suncream for long rides).
I find with a saddle pack my exposure clamp is pushed down onto the frame, so room for one of these does not exist. At 5’9″ I’m sure I’m not alone in this.
Or are other people prioritising radar data over essential repair tools?
wycombewheeler wrote:
Come on, that’s a real stretch, no-one has remotely suggested that and it’s far from inevitable… personally my saddle bag doesn’t preclude putting much on my seatpost, certainly not to the point i’d have to put stuff on the frame, and I imagine that i’m not unique in that but i’m not claiming that it will fit for everyone.
wycombewheeler wrote:
I attached mine to the rear of my saddle pack. Not exactly rocket science.
This gadget won’t show you
This gadget won’t show you whether or not approaching traffic has spotted you and is moving out to overtake. A mirror will do this and you can take evasive action if required. This gadget also won’t work if you have another cyclist on your rear wheel blocking the view of the radar. It will however look stylish on a high-end race bike where a mirror might look out of place.
@hawkinspeter – I’ve got a
@hawkinspeter – I’ve got a brand new 18650 lying around that I bought for a project but never used. If you mail me your address at guyrwood at gmail dot com, I’ll happily chuck it in the post, it won’t get used otherwise.
StraelGuy wrote:
That’s very kind of you, but I’ve got a whole bunch of spare 18650s lying around myself. I tried using a cheap chinese lamp over the winter that used 4x18650s but it was complete overkill (and heavy), so I’ve got far too many already. (I put 4 of them into a battery bank case, but I’ve still got unused ones).
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