Why I Want All My Fellow Riders to Ride with a Rear Light

My Experience with the Garmin Varia RTL510 and Bontrager Flare

Working at a bike shop, you see every type of cyclist walk through the door. You have your mountain bikers, your in town leisure riders, your hardcore commuters, and your even more hardcore roadies. With the exception of the mountain bikers who never really share roads with cars, I would go so far as to say that every cyclist ought to have a rear tail light on their bike.

Over the past few years we’ve seen more and more daytime bike lights from brands like Lezyne, Bontrager, Blackburn, and Garmin. The purpose of these lights isn’t just to make a rider more visible at night, but to catch a driver’s attention well ahead of when they pass you at any time of day. I’ve spent the past couple of years first riding with the Bontrager Flare R, then the Bontrager Flare RT and now the Garmin Varia RTL 510 and I’m writing this to encourage my fellow riders to make sure their bike is equipped with something similar before they head out on the road.

So here are 3 reasons why you should be riding with a rear daytime bike light.


In Canada, if a motorist driving down the road doesn’t have their daytime running lights on they’ll be slapped with a well-deserved ticket. By law in Canada vehicles are required to travel with daytime running lights at all time, you literally can’t buy a car in Canada without them. A motor vehicle is far larger than a cyclist, and it moves with far lower speed differentials to other vehicles than a car versus a cyclist.

So if cars run with daytime running lights, why shouldn’t cyclists? We’re a fraction of the size of a car and we travel at often a fraction of the speed.

Awareness is the key to accident avoidance. Cyclists simply do not have the mass or size of a car and are essentially invisible to motorists. Furthermore, there are not enough cyclists on the roads to make an impact. The everyday car driver is not accustomed to seeing cyclists on the road and, therefore, cyclists are not on the driver’s radar.

If a car driver only sees the occasional cyclist, he does not have a heightened awareness or an anticipatory thought process — “Before I change lanes, I better look over my shoulder to see if there is a cyclist to my right.” Or, “Although there are no cars approaching, I better scan to check for cyclists.” Until there is a dramatic increase in the number of cyclists sharing the road with cars, this automatic, reflexive thought process on the part of motor vehicle drivers will not occur.

If you dig into the numbers in car versus bike accidents, the common thread in nearly every incident is that the car driver was not aware of the cyclist until it was too late and often not until the moment of impact. The most common accident involves a left-turning car driver who simply does not see the oncoming cyclist.


I use a Garmin Varia RTL510, pictured above. The Garmin Varia RTL510 is both a light and a rearward facing radar. As soon as a vehicle comes within about 150m behind my Garmin Edge head unit will beep at me and provide a column indicator on the side of my screen that displays the live proximity of the vehicle to me within that 150m range. At the top corner of the screen the rider is represented by a small radar logo, and the dots appearing further down the screen represent the vehicle(s) within range. 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.

Its literally like having eyes in the back of your head. And while you should be relying first and foremost on your eyes and ears to maintain situational awareness of what is around you, on windy days or at higher speeds a device like this can be a game changer in adding to your senses. Typically as a vehicle approaches, if its safe to do so I’ll give the driver coming up behind me a friendly wave or a thumbs up to let them know that I know that they’re there, and as just a little preemptive thank you for giving me an extra couple meters space.

The beauty of the Garmin Varia RTL510 is that you’ll never be taken by surprise when you’re riding along. When you’re riding along in the city, you should expect that there are always cars around you. But when you’re out on some back country road, or on a gravel ride well off the beaten path, you can go hours without seeing another soul. Lost in that meditative state, or deep in a tempo ride, its easy to ride a few meters in from the edge of the pavement and get caught off guard when you realize there’s a car you’re blocking behind you. With the Garmin Varia, that simply doesn’t happen anymore.

What about other cyclists that you’re riding with? Somehow the radar doesn’t get confused and is able to distinguish easily between riders and cars. And in certain modes, the blink pattern of the light will actually change when it sees a car, which actually gives your fellow riders a heads up behind you that there’s something coming down the road.

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.


Rear daytime lights weigh next to nothing, can be subtly integrated into your seatpost, are often USB chargeable, and have come down in price significantly over the years. An awesome rear bike light like the Bontrager Flare or Ion will run you about $70. And since we’re talking about safety, I’d simply ask, why wouldn’t you use one? I’ll give you a list of things that are more expensive than a humble bike light.

  • A new high visibility bike jacket or jersey will run you anywhere from $100 to $300. And while they certainly can help to make you more visible, they’re only good during the day and won’t provide much help at night. Sure you could also get a reflective jersey or jacket, but now where talking about another piece of clothing.
  • Reflective Bike Shoes are actually a thing, and they’re awesome. The heels of my Bontrager Velocis bike shoes are reflective and while I’m riding at night, the biomotion they create is ideal when it comes to making other drivers aware of my presence, but new shoes are $150-$300 as well, so I wouldn’t go out and buy a pair just for the reflectivity (but your next pair should have some reflectivity…).
  • A new bike if you’re run off the road by someone who was too busy texting to notice that you were there. That’ll run you anywhere from $500 to $10,000 depending on who you ask.
  • Your life. I don’t want to play the fear card, but anything that makes a rider a little bit safer is worth it in my books.

The point that I’m trying to get across here is that we as cyclists are notorious for spending money to chase marginal gains in speed. An aerodynamic or featherweight bike frame will run you a few thousand dollars and save you a couple minutes on that Strava segment. A pair of 50mm deep wheels will also run you a couple thousand dollars and probably save you seconds. A powermeter and bike computer or watch to measure your fitness performance will run you into the hundreds of dollars.

All of these add up to make us fitter and faster, but one simple device can make you safer, a $70 light. So why not?