Rearview Review of the Garmin Varia Radar

Bike Radar Integrated Light

The Garmin Varia radar is a product that has something for everyone. I don’t mean that it will appeal to everyone, rather it has something for the tech freaks, something for everyday bike riders, and something for the haters. You may already know which category you belong to when you think of the radar. Regardless of where you stand on this, in this review of the Garmin Varia Rearview Radar, I find some insights and also plenty of ammunition to support your viewpoint.

Bike radars aren’t a new thing; the earliest bike radar I know of was developed by a South African team who were experienced with radar technology and built a bike specific radar called the Backtracker. They went into crowd-funding to launch their product and during this period Bicycles Network Australia reviewed a prototype version.

The crowdfunding goal however wasn’t met and I subsequently spotted a few signals which suggested that the South African team had connected with Garmin – a logical match for this product. Less than a year later, the bike radar has now launched as a Garmin product. The Garmin version has shed some of the bulk of the Backtracker, is a more polished product, and connects with the Garmin Edge 1000 cycle computer.

Garmin Varia Unboxing

In the box Garmin Varia

Garmin Bike Radardetection

Garmin Varia Handlebar Display Unit

So what does the radar actually do? Let’s start with the basics. The radar has a display mounted on the handlebars and a radar and light unit which is mounted on the seat post, facing rearwards. The display provides a visual alert when vehicles are approaching you from behind and the light unit flashes faster as vehicles approach. It does a remarkable job at this and will track multiple vehicles, though it is limited to line-of-sight. The following 1 minute video shows the Garmin Varia in action.

If multiple vehicles are detected, they are each plotted on your display so that you can see, for example, three vehicles approaching and getting closer. This tracking shows vehicles approaching from roughly 100 meters away. There is also a basic speed indication: an orange light means that the vehicle is travelling at a moderate speed, while a red light means it is travelling very fast.

radar display

The second function of the radar is the integrated rear light which can replace your current rear bike light. The flashing rear light interprets the radar data and, as a vehicle approaches, the lights flash faster to alert the driver.

Bike Radar Light

I was curious, while reviewing, whether there were any significant differences between the Garmin Varia and the prototype BackTracker which I trialed a year before. The manufacturing quality is certainly more refined, which you would expect from a mass-produced electronic product. The USB ports for charging are integrated nicely and it incorporates the familiar Garmin mount (90 degree turn and it locks into position). The display can be mounted on the stem or handlebar and uses the traditional two o-rings to hold the mount into place, though I would recommend an out-front mount.

Garmin Varia Charging USB

A few mounting options for the radar/light unit are provided and I needed the aero seat post mount which was fastened with an o-ring. While the o-rings work, they will loose elasticity over time and I would be concerned about them snapping or loosing tension unexpectedly while out riding. For round seat posts, a clamp style mount is provided. Most cyclists should have enough space available to mount even with a saddle bag though if your saddle is set low, consider the space which is available to mount the radar.

garmin radar mount

Garmin Varia Round Seatpost

O ring bike mount

Bike Radar Detect Cars

For the display unit, I would have preferred a flatter / streamlined design. The alternative is a Garmin Edge 1000 cycle computer which you can link it to the radar; a convenient approach which also reduces the number of devices on your handlebars. For this review, I didn’t trial this option.

Radar Display unit mount

Varia Bike Radar Display

Charging is straight-forward; plug the provided (mini) USB cables into each device and when the green dot stops pulsing, charging is complete. The provided USB cables however are quite short and because there are two devices to charge, if you are used to charging your devices from your computer, they may be competing for power.

The on/off button for both is subtly integrated. When I first unpacked the units I had to look closely to locate them, but I do appreciate the design which is reduced to the essentials.

Display Bike Radar


Does the bike radar actually work?

Yes – it effectively detects cars… and ignores other things such as bike riders, trees, buildings, or vehicles travelling in the opposite direction. Simply, the Varia radar detects objects moving towards it only, and only above a certain threshold of speed/size. Everything else is ignored. It’s amusing when a large bunch of cyclists approaches (at catch-up/passing speed) and get detected. Motor cyclists were, as a rule, accurately detected.

But there are situations in which is doesn’t work well. The obvious limitation is due to line-of-sight; if you are cycling in an area with lots of twists and turns then you can’t expect vehicles which are out of sight to be detected. Another difficult situation is when vehicles are following you, waiting to overtake, and are travelling at the same speed as you. I experienced vehicles suddenly disappear, but a quick peak over my shoulder confirmed that they were still there. Similarly, at traffic lights and in slow moving traffic, these were not situations where the radar was reliable.

So, let’s get down to it and talk about the value of using this hi-tech gizmo. Why can’t you just use a mirror instead? A rear-view mirror is a far cheaper alternative and provides similar information – visual confirmation. If you opt for a helmet mounted mirror, you don’t even have to tilt your head to look down at the display. Where the Garmin Varia differs is that it can more effectively provide an indications of the distance and speed of one or more vehicles approaching. The radar has decent reach in all lighting conditions, so a vehicle far behind will be registered sooner via the radar than by a rear-view mirror in most cases. When it comes to comparing a mirror and the radar there is an overlap, but each method also has unique advantages.

The most compelling question is, what do you do now that you know one or more vehicles are approaching? This is a question that could be debated endlessly by cycling enthusiasts and, rather than outline all of the scenarios, I will tell you what I do. Generally I cycle towards the left side of the lane to allow vehicles to more easily overtake, except in scenarios where I need to ‘claim the lane’ to ensure my own safety and limit dangerous overtaking attempts. When the display alerts me that a vehicle is approaching, I usually do nothing more than continue on my way, but I also appreciate knowing that a vehicle is about to pass. There are however situations where I react; if I am too far over in a lane, I will move towards the side. Or in a bunch ride I may be able to detect the approaching vehicle first and can call ‘Car Back’ which provides this useful information to the other riders.

Car behind cyclists
The bunch moving to single-file to let vehicles overtake

The radar never replaces a look over shoulder, especially when changing lanes. The radar provides useful ‘heads-up’ information, for example if I need to cross over a few lanes of traffic I can recognise that the coast is clear and the radar indicates no more traffic, then I look to check before signalling and moving over.

One of the inherent problems of this systems is that you have to look at the display, or have it in your field of view to see an alert. With a cycle computer you choose when to look down and absorb information, with the radar display it is not in your field of vision while cycling so you can miss a useful alert.

I’ll conclude this review with a prediction: heads-up display is on its way to cycling. This technology will take a few years to really come through, but there are already a few devices out there such as Google Glass or the Recon Jet, which is sports specific eyewear and features heads-up display capabilities. Imagine radar and video data being combined to provide an accurate picture of the road and traffic behind. With a heads-up display you would get a visual alert in your field of vision which guides you to focus on the display to see more detailed data such as video or information on the approaching vehicle. But for now, we need to be content with the first iteration of next generation bike tech.

Google Glass Cycling
Google Glass promo image © Google


Do you, or don’t you?

The Garmin Varia is the first commercial bike radar in what will likely be an evolution , so it is certainly a product that will appeal to first-movers. At $389 RRP it’s on par with other top-of-the-range bike gear investments such as cycling shoes, a helmet, or an action camera. Long distance cyclists who cycle in remote areas with infrequent traffic my place more value on advance warning of incoming traffic whereas a commuter cyclist, who already anticipates vehicles coming from all directions, may not see significant advantages.

If you were intrigued from the start or want to be first off the rank, then the Garmin Varia bike radar is for you. But if you never liked the idea, nothing in this product will convince you to buy it… yet. The more I used the Varia radar the more I have enjoyed it being part of my hi-tech cycling ensemble. This is one for my Christmas wish-list, after a new helmet.

For more information and purchasing options for the Garmin Varia Bike, visit Garmin Australia

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About The Author

Christopher Jones is a recreational cyclist and runs a professional design business, Signale. As the driving force behind he has one of each 'types' of bicycles.

2 responses to “Rearview Review of the Garmin Varia Radar”

  1. John Hawkins says:

    Where I see this technology adding real value is in being teamed with a camera and distance measurement to provide automated capture of drivers passing too close in jurisdictions where there is a minimum safe passing distance law.

    A widely available product like this would make a tangible difference to cyclist safety and challenge the resistance of some law enforcement agencies to policing these rules.

    Until this is done I don’t see what pain the product is solving that isn’t cured more effectively by the humble mirror.