How Cargo Carriers Work

Need a carrier
Sure, he's got plenty of space right now, but how much more stuff can he cram in the back of that car? This guy needs a cargo carrier, fast.
Flying Colours Ltd./Getty Images

With the effectiveness of modern fertility drugs and the seemingly endless amount of stuff children require when traveling, a family car can get awfully cramped. Fortunately, parents today don't have to choose between leaving one of their kids at home alone to make room for an extra suitcase. Thanks to cargo carriers, a lot more much-needed space comes in a long-overlooked place: outside the vehicle.

A number of companies manufacture cargo carriers that can hold everything from plain old luggage to high-end mountain bikes. These simple marvels of ingenuity make it possible for a person to enjoy his or her favorite (and space-demanding) activities without having to shell out tens of thousands of extra dollars for a larger truck or conversion van. How else can someone speed down the highway with a pair of skis attached to the roof or all of their luggage in tow without buying a big conversion van or pick-up truck? Cargo carriers, that's how.


OK, so you're sold. You can finally put those water skis to use again, or maybe it's time to get back into cycling. There are a lot of choices depending on what kind of uses you'll have for your cargo carrier. If it's extra luggage you've got and a station wagon you drive, a roof rack might work best. If you have a mid-size SUV and like to camp, then a trailer hitch cargo carrier should suit you just fine.

Regardless of whether your cargo carrier is roof-mounted or hitch-mounted, HowStuffWorks can help you install it. You'll be surprised how easy it is. When you're ready to learn, turn to the next page.



Installing Cargo Carriers

Cargo carrier
There are a variety of cargo carriers; we've focused on roof racks and hitch-mounted varieties.
Philip Gatward/Getty Images

There are two places for a cargo rack to be installed: on the roof or to the rear of the car. Both have benefits and drawbacks. Roof-mounted carriers can provide more surface space for your extra stuff, but can cut down on your vehicle's aerodynamics. Roof-mounted cargo carriers can also prove problematic in low clearance height situations like a parking deck. Rear-mounted cargo carriers are helpful because they provide extra space without cutting down on the vehicle's aerodynamics. They do leave your extra cargo vulnerable to fender benders, though.

Whichever you decide is best for you, here's a brief primer for installing a roof- or rear-mounted cargo carrier. We'll start with the roof-mounted carrier. Before we begin, remember to consult your cargo carrier's manufacturer instructions before installing your carrier.


To install a roof-mounted cargo carrier, you're going to need a roof rack. Many automakers build SUVs, wagons, minivans and some sedans with factory-installed roof racks already attached. If your car doesn't have a roof rack, you can install one yourself. Previously, this meant you had to drill holes in your car's roof. Some roof rack systems today circumvent that process by clamping to the car's rain gutters [source: Rack Attack]. These small, curved lengths of metal move water away from your car's windows and serve as a sturdy support for a roof rack. Because of the different designs and locations of rain gutters on cars, be sure to get a roof rack system that's been designed specifically for the make, model and year of the car you have.

Considering you've got a roof rack, it's time to mount your cargo carrier. Your roof rack should consist of two raised stationary parallel bars that run front-to-back along your car's roof (side rails) and at least two more moveable parallel bars that run side-to-side along your car's roof (crossbars). With roof-mounted cargo carriers, you have three general options: luggage baskets, which can hold luggage, bikes, kayaks and other items; cargo boxes, enclosed, hard-shell containers that can hold anything you can fit inside; and cargo bags, which are like cargo boxes, but aren't made of sturdy plastic.

Regardless of which type of rooftop carrier you buy, most make use of the width created by sliding the crossbars apart to stabilize the load. With the crossbars apart, the rack or box carriers are installed with brackets and screws that create a clamp to attach and stabilize the carrier to the crossbars. A simple turn of a few screws and most cargo carriers are installed. Be sure to check the tightness of the brackets and screws from time to time, especially on long trips.

If you don't want to install a roof rack, you may want to look into a rear-mounted cargo carrier. Almost all of these carriers make use of a trailer hitch. Like roof racks, many vehicles are manufactured with trailer hitches installed. If you don't have a trailer hitch, install a 1-1/4-inch (3.175 centimeter) interchangeable hitch. This allows you easily to switch between a ball hitch for towing and a cargo carrier.

There are a variety of rear-mounted cargo carriers. Most of them slide easily into the interchangeable hitch. A cargo tray, for example, is much like a roof-mounted luggage rack, with a sturdy frame that slides into the trailer hitch. If you have a cargo carrier that requires a larger or smaller trailer hitch receiver, this is easily fixed with an adapter.


You've got your basic cargo carrier installed, but wait, there's more. Read about some of the accessories and additional parts you may need.


Additional Parts Needed for Cargo Carriers

Roof rack
This VW van has an aftermarket roof rack installed. The luggage looks strapped down. Good. Wait! Don't forget the luggage cover.
Ulriche Hammerich/iStockPhoto

There may be a few more things you'll need before taking off for the great outdoors or on a nice, long vacation. For example, we don't recommend you simply toss your bike or your suitcases on to your roof-mounted luggage basket and go; you'd most likely wonder where exactly your stuff fell out.

The suitcase problem is easily fixed. There are some low-tech solutions, like luggage nets that hold your cargo in place and snap to your luggage rack. It's also a good idea to look into all-weather covers or bags to protect your things from the elements.


To carry a bike, snowboard, kayak or surfboard on your luggage rack, you'll need an additional part. These are specially designed racks that keep bikes, kayaks and surfboards upright and stable. Ski racks hold skis and snowboards in place. Some models include a bar that lies on top of the crossbars. The bike sits in this extra bar and is held tight by fasteners. Some rear-mounted carrier baskets allow for similar accessories.

It's also a good idea to invest in some good locks for your cargo carrier to prevent someone else from helping himself to your stuff while you're parked. Cargo boxes in particular usually come with locks already installed, but there are additional locks on the market for everything from cargo boxes to snowboard racks. If you have a rear-mounted carrier, be sure to use a lock for your hitch as well, so thieves can't take your stuff and your carrier, too.

There are also some safety issues with cargo carriers that can be addressed with some well-placed accessories. Since it's mounted on top of the car, a roof-mounted cargo box doesn't get in the way of brake lights, but this can be a problem with rear-mounted cargo carriers. If you have a rear-mounted cargo carrier, you'll want to look into purchasing a brake light kit. These additional brake lights mount onto your rear cargo box and sync with your brake pedal. You might be surprised to find a plug designed just for this purpose beneath the rear of your car. With most brake light kits, you simply mount them and plug them in. There are also some rear-mounted cargo carriers on the market that have brake already built in.

With a well-installed cargo carrier and any necessary additional parts to make it safe, you'll be road tripping in comfort with lots of extra space in no time.

For more information on towing and other related topics, visit the next page.



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  • "Frequently asked rack questions." Rack Attack.
  • "Load Warrior." Yakima.
  • "Technical support and instructions for roof mount bike rack #64720." Pro Line Racks.
  • "Thule Terrapin cargo box." Auto Anything.
  • "Time Travel series." Thule Car Rack Systems.