Do You Need a Rear Bike Light?

April 05, 2022 6 min read

Cycling is a great alternative to cars and walking as a mode of transport; a bike doesn't use fossil fuels or contribute to carbon emissions, but it is quicker than walking while still offering an effective exercise opportunity.  

Many developments have been made over the years to make sure that cycling is as safe as possible for people who choose to get around in this way, and there has been a steady increase in the number of bikes on the roads. 

When you cycle, you will need to be prepared for all kinds of external conditions, including awkward weather and darkness. These can affect the visibility of all road users, which can make it difficult for both you to see them, and them to see you. However, there are certain things that you can do to try and prevent accidents from happening due to one party not being able to see properly. 

One of these things is fixing a light onto the back of your bike. This is known as a rear light or tail light, and it alerts traffic behind you to your presence. Even if it's so dark that they can't see your outline or anything else about you on an unlit road, they will know that there is someone there sharing the same road as they are.  

What Does The Law Say About Rear Lights? 

In order to understand what kind of lights you need to install on your bicycle, you first need to understand what the law says about them. The requirements may be different depending on the country you are in, as places have their own rules and regulations for public road users.    

In the UK, The section of the Highway Code that deals with this topic at the time of publishing states:

"Rear lights must be fitted at least 300mm (1 foot) behind the furthest point where the reflector is visible." 

This means that the light should be mounted no further forward than the last reflective part of the rear wheel, and you can only mount it within 1 foot of that position. As well as this, you shouldn't put your hands on the handlebars when you ride, because this could cause your headlight to become obscured.

In some countries, such as New Zealand, Australia, and Canada, you also need to ensure that the light isn't blocking out your front light when you are riding in daylight. If you don't want to block out any other light source, then you will need a separate light that is capable of shining forwards onto the ground in front of you. 

While tail lights are not required by law in many US states, it is still a sensible idea to have them. However, it is illegal to ride a bike without a rear reflector, so you absolutely must have one of these, as well as pedal reflectors and a white headlight. 

Just because you cannot be prosecuted for not having a rear light, doesn't mean you won't needlessly put yourself and others in danger without one. 

Why Do We Need Rear Lights?

There are many reasons why you might want to consider installing a rear light on your bicycle. We have touched upon some of them briefly, but you might not fully understand them yet. The most common include:

Safety - A rear light can help to keep you safer by alerting drivers behind you to your presence, even if you are unable to see them. It also keeps them safer and avoids unnecessary accidents that might happen otherwise, when you encounter blind bends or junctions.

Visibility - When you are cycling during the day, you need to avoid having your headlight blocked by objects such as signs or trees. By having a rear light installed, you will be able to see everything clearly. You can also stay visible to others while riding at night. Without a rear light, you may find yourself suddenly becoming invisible to drivers, which can lead to an accident.

Traffic flow - Having a rear light allows you to more easily follow the direction of traffic around you. It makes it much easier for cars to see you, and vice versa. This can give you a better idea of how fast people are travelling, allowing you to react accordingly when driving. Also, you can tell who has stopped or slowed down, enabling you to plan your route accordingly. 

How To Install A Rear Light

The best way to get started with installing rear lights on your bicycle is to find a suitable bracket. There are two types of light mounts that are commonly used:

  • Mounting brackets - These attach directly to the frame of your bicycle. They are usually made from metal, so they won't rust over time. However, they require drilling holes into the frame of your bicycle, which can weaken its structure.
  • Adapter mounts - These are designed specifically for bikes with fenders. They come in various sizes, meaning that they can fit a range of bicycles. They work by attaching to the bottom of your fender, rather than onto the frame itself. Once attached, they allow you to mount your light anywhere along the length of the fender. Some adapters also feature additional mounting points, allowing you to install the light higher up to prevent it being covered by mud.

You will first need to decide where you would like to place your rear light. Most cyclists choose to mount their lights somewhere near the middle of the bicycle's back end, just before the chain stays. To do this, you'll probably need to drill holes into your frame. If you're using adapter mounts, you'll need to purchase a special tool called a "fender hole punch" to make these holes.

Once you've decided on a spot, you'll need to measure your fender and mark the position where you'd like to place your rear lamp. Then use a ruler to measure the distance between those marks. Next, drill through both layers of material (the fender and the frame) until you reach the other side. Repeat this process until you have all the necessary holes drilled.

When you've created all the necessary holes, you'll need to insert a bolt into each one. This should be done by threading the bolts into the holes and turning them clockwise. After inserting all six bolts, tighten them firmly.

While this guide should work for most rear bike lights, there may be some that require different installation methods. Always read the instructions that come with the specific model you buy, so that you don't run the risk of damaging them through improper installation.

Are There Different Types of Rear Lights?

Like with anything else you can buy, there is a lot of variation in terms of the lights that are available to you. These range from basic models with only one power setting, to ones with a multitude of beam patterns and light levels. You will also need to consider how many hours of battery life you will get, and if your light requires removable batteries.

Ideally, you need something that emits a bright beam of steady light output, and has a power button that is easy to work. You should be able to keep the light visible at all times. However, you may not be satisfied with just a simple light, as you may find that you'd prefer a more powerful light with different power levels. Other features are also helpful to have, such as a high waterproof rating for cycling in the rain.

Fortunately, you can purchase a light that has advanced uses. For example, you will definitely need active lighting when cycling at night, but you may only need passive lighting during the day. It drains the battery levels if you keep constant lights on throughout the day, as daytime visibility is usually better anyway.

Because of this, it is a good idea to have a rear light with a day flash mode, such as the Blackburn Dayblazer. This particular set comes with both a front white light and a rear red light. It has various light modes that can help you adapt to different conditions, such as levels of natural ambient light and street lighting, light pollution, and a powerful setting for driving on rural roads or unlit roads.

These light modes include constant modes, steady modes, and flashing modes according to the situation. When you need a steady beam or a strong beam that stays constant, the first two are the ones to pick. 

You may decide you need a flash pattern to make yourself more noticeable, so that is also available for maximum visibility. Similar settings are also known as pulse modes, so look out for those words in your search.

Final Thoughts

As you will have learned, rear lights may not be a legal requirement, but they are definitely a worthy investment to ensure your personal safety. There are many types of tail lights on the market, including ones with removable batteries and ones that are USB rechargeable or have a power bank.

It's not necessary to have the brightest settings and max power engaged at all times, especially in bright sunshine when there is a lot of active lighting around - you can use the lowest setting and still have enough light visible. However, on unlit roads in urban environments or on rural roads, as well as low daytime visibility, it is good to have the maximum output possible for a good degree of all-around visibility.