Rear bike lights are all about being seen, not being used to see. This means you will see much lower lumens on a backlight when compared with front lights, but that doesn’t make them any less effective. With rear bike lights, it’s not about how bright they shine but how well they function as a light.
What is a lumen?
A lumen is how bright a bulb is. The higher the lumens, the brighter the bulb; a 60W bulb, for example, is around 800 – 850 lumens. However, bike lights, especially rear bike lights, won’t be able to get this high of a lumen number. They’re usually around 75 lumens for the lower-priced lights. You might think this is relatively low, but the bike lights are incredibly visible due to clever LED tech and how they flash.
What to look for in a rear light?
A rear light should be functional to your riding – if you ride in a city, a light which gives a flash cutting through the traffic is vital. This will help car drivers see you and hopefully give you space.
Road riders who ride outside the city might require a steady ‘on’ light with a flash that can be seen from a distance. You can also get rear lights which, using radar and sensors, pick up on cars behind you and flash to alert the driver that you are there.
What are the best rear bike lights?
What’s The Best has already rounded up the best bike lights so you can see where you’re going and be seen, so let’s now look closely at the best rear lights to help keep you out of trouble on the roads.
Best small rear bike light
www.wiggle.co.uk
Description
This small, lightweight, inexpensive rear light will clip onto your helmet and attach to your seat post, backpack or clothing to help you be seen on the road. Weighing just 12 grams and with three different light modes, it could be the perfect rear light for someone competing in a time trial race and a secondary rear light for a commuter in the city.
Pros
- Lightweight
- Inexpensive
Cons
- No quick release. You detach the whole light and mounting
Best rear bike light for visibility
Description
A handy little light from Lezyne, putting out only five lumens but has a visibility of 270 degrees, enabling you to be seen at junctions and roundabouts better. With five output modes, the Femto can run up to 15 hours, meaning your daily commute could be covered in one charge. The durable construction has an IPX7 water resistance rating with a threaded cover to keep the USB charging port clean and dry.
Pros
- Wide angle of vision
- Long run time
Cons
- Not the brightest rear light on the market
Best rear bike light for battery life
www.tredz.co.uk
Description
Another Lezyne light, but this one is a bit more substantial and offers up to 75 lumens of light from its LED bulbs with five different output/flash modes to give you maximum visibility. A neat little feature of this light is an integrated USB, meaning that it will charge cable-free, so you never have to search around at the bottom of your kit bag to charge your light.
Pros
- Bright flash at 75 lumens
- Only 45 grams in weight
Cons
- No mount for a quick release when you’re not riding
Best designed rear bike light
Description
When the first Blinder launched in 2012, it became an almost instant classic Knog product—beloved for its compact design, easy operation, adaptable attachment system and powerful output. Super bright at 100 lumens, an integrated USB means hassle-free cable-free charging; there is also a power indicator to show you how much battery life is left. Changeable graphic flash patterns mean that you can change how the light flashes, making it more distinctive.
Pros
- Battery indicator
- Bright at 100 lumens
- Low battery indicator
Cons
- No quick-release mount
Best rear bike light for commuters
www.trekbikes.com
Description
Bontrager is a very well-respected brand with many front and rear bike lights offered. This, the Flare R City, is the most popular bike light that they sell. It’s easy to see why as it’s great for commuters, the intelligent automatic ambient light sensor adjusts the light's beam brightness to match the conditions.
A neat little feature is the battery safe mode, which kicks in when the battery is at 5%, hopefully putting the light in its lowest setting to get you seen all the way home.
Pros
- Perfect for commuters
- Quick connect bracket
- Intelligent automatic ambient light sensor
Cons
- Hard to find cons, but it can take four hours to charge from flat
Description
Knog makes some quality bike lights, and the Blinder is no different. Putting out a blinding (sorry, not sorry) 70 lumens, it’s a bright light that cuts through the light noise on the city streets. With side lights, it also offers a wide field which you can see.
Pros
- Wide angle of light
- Bright at 70 lumens
- Respected brand
Cons
- No quick-release bracket
www.condorcycles.com
Description
The subtle Zecto Drive 80 is anything but subtle once turned on, and you’re riding, pumping out an impressive 80 lumens and ensuring you’re seen on the city streets and the country lanes. The rubber strap will fit around aerodynamic and regular seat posts, which means no quick release. This can be annoying as you always have to remount the light when you ride after taking it off for security.
Pros
- Bright
- Great for commuting and further afield
Cons
- No quick-release mounting
Best rear bike light for helmets
www.tweekscycles.com
Description
Exposure by name and exposure by design – a trick little light that will mount to your seat post or your helmet, giving a maximum of 75 lumens of light. Great for commuters, it's super bright flashing and versatile mounting means you can get more than one rear light on you, giving you a greater chance of being seen. An inbuilt fuel gauge will show you when you need to charge your light, which is very handy.
Pros
- Bright at 75 Lumens
- Quick release mount
- Attachable to the seat post or helmet
Cons
- Seatpost mount can get knocked sideways
Best reactive rear bike light
www.chainreactioncycles.com
Description
In the Chain Reaction Black Friday sale, the Exposure Blaze Mk3 is a great rear bike light with a neat little brake light feature. When it detects deceleration, under braking, it will flash at 150 lumens, letting those around you, drivers or other bike riders, know that you are braking. Even when this ReAKT system isn’t working, the light still punches out a powerful 80 lumens.
Pros
- ReAKT braking system
- Bright at 80 Lumens (standard) and 150 lumens when braking
- Durable and rated IPX6 for water resistance
Cons
- High price, but we think it’s worth it
Best rear light technology
Description
A bike light is well worth having if you have a Garmin or Wahoo bike computer. Called the rearview because the radar inside the light will pick up on vehicles up to 140 meters behind you, alerting you via your bike computer or smartphone app. It will also adapt to your riding. If you’re in a group, the lights ‘peloton mode’ gives a lower-intensity flash so as not to dazzle your fellow riders.
Pros
- IPX7 water resistance rating
- Links to Wahoo and Garmin bike computers
- Alerts you of what’s behind
Cons
- High price
Best rear bike light and camera combo
Description
If you want that extra protection when cycling around the city or country lanes, this from TOOO is a rear light and a camera. In the unfortunate event of an incident, the DVR80 will record in full HD with an angle of 105, even at night, thanks to the SONY IMX 323 camera sensor. Recording at either 30 or 60 frames per second, image stability is high so that you can see what happens as clearly as possible.
Pros
- 80 Lumens of light give you a bright rear light
- Records in full HD 1920x1080P at 30fps or 60fps
- IPX5 water resistance
Cons
- High price, but there’s a lot packed in
Best premium rear light
Description
Three hundred and forty-five pounds for a rear bike light? Yes, it’s a very high price; let’s try and break it down as to why you would be paying that much for it. Consider the Garmin Varia Rearview Radar RTL515 Bike Light above has an RRP of £124.99.
Add to that a camera which films in 1080p at 30 fps or sets the resolution at 720p to extend battery life for longer rides.
The mount on this securely locks it to your seat post, so there’s no chance of it coming off while riding, and it’s super easy to take it off and put it back on again. The camera can run continuously, be turned off or be turned on when the radar detects a vehicle approaching.
The RCT715 really impressed us when we tested the light - if you can afford it, we can't recommend it enough.
Read our full Garmin Varia Radar RCT715 Camera Rear Light Review
Pros
- Bright
- Warns you of vehicles behind
- Works well riding in a group
- Records in 1080p at 30 fps
- Securely mounted
- 16GB SD card included
Cons
- High price
Frequently Asked Questions
Am I legally required to have a rear bike light?
No. However, while there is no legal requirement to ride with a rear light, we recommend that whether you’re riding in the day or the night, you ride with one. Lights will greatly increase your visibility, keeping both yourself and pedestrians safe.
Though lights are not legally required, a bicycle should be sold with reflectors and a bell by law.
What to look for in a rear bike light?
There are a few things that we like to look for when buying a new rear bike light.
A rear light should have a decent flash to cut through traffic disturbances. We also like lights that are easy to take off the bike and mount - this makes it easier when you’re done riding and reduces the risk of them being stolen.
Is it all about how bright they are?
Front lights tend to be more about brightness, but with rear lights, it's not such a concern. This is because they are about being seen, and a light which is pulsing or flashing is more likely to be seen than one which is steady.
What functions should my rear light have?
Rear lights often come with more than one mode of flash patterns; when you get your light, test to see what these patterns are and choose the one you feel most comfortable with. Remember, these aren’t to see with but to be seen.
Whether you want one with a camera on or a radar is up to you, these are fantastic to have to provide evidence, but there is nothing to say the police will always use it as such.