Black Friday essential tech discounts – I thought this device was a joke, now I never, ever ride without it

Radar? Seriously? What kind of cyclist needs that? This was my reaction when, just a few years back, my older brother, an Englishman who has made Connecticut his home, told me he and his US riding buddies were all riding with Garmin radar-equipped rear lights. “Try it,” he urged me, “I now hate riding without it.”

His was an earlier unit than the Garmin Varia RTL515 I’ve found heavily discounted for Black Friday, but it worked in exactly the same way. Essentially, the Varia RTL515 is no bulkier than a typical super-powerful rear light – it’s visible from up to a mile away, and in bright sunshine – but the housing contains a radar sensor. This can detect cars, motorcycles, vans and other vehicles from 140 metres away.

Being stubborn, stupid and wanting to appear superior I remember declining his offer to try what I mistook for a lame joke. Fortunately, my younger brother, who lives and rides in the English Lake District didn’t. So, when I caught up with him a few weeks later he told me: “Try it, I now hate riding without it.” So, I tried it, and you know what? I now hate riding without it.

Here’s why. Every time a car approaches from behind, its position and speed are picked up by the Varia unit, which relays that information to your head unit or phone via Bluetooth. No, it doesn’t have to be a Garmin head unit and the phone app is free – all you need is a suitable handlebar mount.

The location of the vehicle is indicated by a dot on a slender line running up the side of your screen and, of course, it changes position as the car gets closer or hangs back. If the vehicle turns off at a junction then the dot simply disappears. If a car is approaching particularly quickly then the line turns red to alert you. Audible warnings, which can be muted, are also sounded.

It goes without saying that the Varia RTL515 can locate multiple vehicles, not just one, so it works brilliantly on roads with quiet to moderately busy traffic conditions. Being able to tell exactly what’s behind you on a fast, busy A-road or highway is a godsend. Similarly, being warned of occasional fast-moving traffic on otherwise quiet country roads is so reassuring when dodging potholes, especially if wind or rain noise makes it difficult to hear the sound of an approaching engine or electric vehicle.

Quite honestly, in heavy traffic, it’s not really a viable solution because your screen will always be filled with moving dots, so bear this in mind if you’re an inner-city commuter.

How much of a convert am I? Well, not only do I never ride without it, but I’ve since bought Garmin Varia RTL515 units for my wife, my son and my daughter. I have no solid evidence that we’re any safer, but I do believe in the idiom ‘forewarned is forearmed’. If you know in advance that something is about to happen, at least you can take action. Better that than riding blind.