What to look for when buying a Cargo Rooftop Bag

Are you thinking about buying a cargo roof top bag for a road trip or journey? In this article I share the key areas of weakness in a car roof bag and what to avoid when making a purchase.


The first thing to assess when buying a bag is how big you need it to be. Most people agree that the bigger the bag the better but before you go out and buy a bag big enough to house King Kong, go get a measuring tape out! Your vehicle needs to have enough roof space to fit the bag so its important you have the dimensions of available roof space for your vehicle before you make the purchase. Measure the length of the roof and width. Also check your vehicle handbook or ring your vehicle dealer to find out the roof load bearing capacity to ensure your vehicle has enough strngth in the roof to carry a bag. Are you going to fit a roofbag without roofracks? If without then do you have roof rails? If so measure the available space within the roof rails. If you do have a roof rack, does the rack move or is it fixed in place? If it’s fixed, again measure the space available within the racks. Most bags will fit within the space inside of the racks but an alternative option might be to put the bag on a platform on top of the racks if required. Now you have your measurements you can start to assess how big a bag you can buy. Most bags are either measured in Cubic Litres or in Cubic Feet and here’s a rough guide to sizes:

Small Bags: 5-10 Cubic Feet or upto 250 Cubic litres

Large Bags 10-20 cubic feet or 400-600 Cubic litres


Strength is the key to a great roof bag. Typical areas of weakness are straps, seams, buckles, zip, material:

Straps: Ensure attachment straps are at least 2 inches wide for maximum strength. Webbing (car seat belt like) material is the strongest. Straps should be double stitched.


Your bag is going to get wet, really wet and you don’t want any water ingress as it could ruin your kit so waterproofing measures for your bag are really important. Cheap bags will typically have stitched seams (avoid!) and a regular zip these both leak water like crazy so if you are on a limited budget make sure you double bag all your kit with trash bags before travelling. Also if a bag is made with nylon denier material, altough tough, it also leaks after a good downpour. The better the bag the better the waterproofing so features to look for include: Sealed zips, Velcroed storm flap on zip, electronically heat welded seams and waterproof tarpaulin material


How does the bag attach to your roof? Each bag available comes with a different fitting and some are easier than others to attach and secure the bag to your car. If you have a vehicle with roof rails or racks it makes life easier when choosing a bag as most roof bags attach with standard plastic clips and straps to the rails. If you dont have any rails or racks then choose carefully. There are only 2 or 3 cargo roof bags available which work without roof racks. They typically either attach by threading straps though the doors and securing with a clasp under the roof in the actual car itself or they attach with hooks underneath the rubber seals of a door so ensure your seals can be pulled down before buying this type first.


Strength, size, water resistance and secure fitting are the key points to remember when buying a roof bag. If you consider all these points first you will only ever need one roof bag and it should last you a long time!



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