Whether you’re moving home, taking the family on a camping holiday, or planning a road trip, investing in a roof or bike rack can provide extra space and comfort. To help ensure this is done safely, International Drivers Association has put together a comprehensive guide. We cover how to safely transport your load, while avoiding frustrating fines and any potential car insurance voids. 

Bike Racks

Bike Racks

Permissible roof weight

Before purchasing or starting to load your roof rack, you will need to find out the permissible weight allowed for your car. The permissible roof load of a vehicle can be found in the operating manual and will confirm the maximum weight you can safely load your car up to. It’s important to note that the overall weight includes the weight of the rack itself, not just the objects placed on it.

An example weight for the Volkswagen T5 is 50kg, the equivalent of two adult-sized mountain bikes or two medium-sized suitcases. This is classed as a large vehicle, so most other family cars will have a much lower overall weight.

Fitting a roof box

There are a few things to be sure of when fitting a roof rack. The Highway Code states: “You must secure your load and it must not stick out dangerously”, so ensure that your roof box not only fits the weight limits of the vehicle, but also the measurements. It is important that your rack does not hang over the edges of your vehicle, and that it is not too far up from the roof.

Airflow will lift the front of the rack, especially at higher speeds, so make sure to securely fix the rack to your roof to avoid any movement once your journey is underway. While this might seem obvious, it’s vital to ensure a clear line of sight for the driver.

As well as the permissible roof weight, it’s also worth considering the overall vehicle weight. Some useful calculations to ensure the safety of your rack are:



Sticking to these guidelines will help you ensure your rack is safe. If loads exceed certain lengths or widths, you might have to give advance notice to the police, including details like the time, date, and route of your proposed journey, however this should only be in special circumstances.

Bike racks

For drivers looking to transport their two wheels, there are a few different types of bike racks to consider. One is a tailgate rack, which are a popular choice, but are generally not recommended by car manufacturers due to vehicles often not being designed to bear this type of weight.

Another option is a roof-fitted bike rack, which allows for a number of bikes to be fixed onto the top of a vehicle. If using one of these, make sure to follow the permissible roof weight guidelines as previously mentioned.

It’s important to note the height this adds to your vehicle, as it may mean certain underpasses are not accessible. This method also impacts fuel consumption, as the bikes up top will create drag.

The most recommended method of transporting bikes is through a tow-ball and bike carrier system. This set up securely attaches to the back of your vehicle, giving you the most efficient method of carrying bikes.

Rules of fitting bike racks

When fitting a bike rack to the back of your vehicle, it is important to make sure your number plate and brake lights are still fully visible to drivers behind you.

Drivers could be fined £1,000 and your car could fail its MOT test if you drive with an incorrectly displayed number plate. You can purchase number plates that can be fitted to the back of racks if covering your plate with your bikes is unavoidable.

Covering your brake lights is also considered to be a major safety risk, which could see you charged for dangerous driving. Fines can rise to a massive £5,000, plus up to nine penalty points. In some extreme cases, motorists could also find they face a temporary driving ban.

Bike racks may also get in the way of a driver’s vision when mounted on the back of the vehicle. It is important that you fit the rack and bikes in a way that doesn’t stop you seeing the road. Be sure to check how your vision is with the rack fitted while you are stationary. If there is obstruction blocking your view, you will need to readjust the rack. 

Tips for roof box and bike rack safety

  • Equipment such as bike racks or roof boxes could be classed as a modification and might not be covered by your car insurance policy. Make sure to check with your insurer before setting off and take out the necessary supplemental insurance if required.
  • Bungee cords can be a great way to keep bikes securely fastened in. We recommend tying the wheels of your bikes together too, as this minimises the chance of movement while in transit.
  • Chances are your bike will be suitable for the recommended rack system. If you have a particularly heavy or large bike model, it may be worth doing some extra research around how much your chosen bike rack can hold.

The International Drivers Association advises:

“Using roof boxes and bike racks are a great way of transporting heavy loads, we just need to make sure drivers are aware of the laws and safety concerns around using them.

It is your responsibility to ensure the weight of your rack is suitable for your vehicle, and that what you are transporting is securely fastened in. The rack should not hinder you while driving, so make sure your vision is not obstructed in any way and everything is secured. It is also important not to impact other drivers around you, so make sure nothing is sticking out in a dangerous manner.

We recommend you take out supplementary insurance, if you are not already covered by your existing policy.”

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