Average folks must think we're nuts when they see our rigs go whizzing by completely covered in steel tubing. Who can blame them? It takes a hard-core wheeler to really appreciate the beauty of a vehicle wrapped in steel tubing. So if you're new to wheeling and just don't get all the steel stuff, let us explain the basics of rollcages and exo-cages to you.
Rollcage Basics
In the most basic of explanations, a rollcage is a protective steel frame of tubing built inside the vehicle to protect its occupants in the event of a rollover or accident. Rollcages are readily available from aftermarket manufacturers and off-road fabricators, but they will likely be called something else for liability reasons, such as sport cages or trail cages. However, even under a different name, many offer protection and safety.
Exo-Cages
There aren't too many manufacturers that sell exo-cages or kits. Exo-cages, which are built on the outside of the vehicle, are mostly one-off custom builds from specialty off-road shops. To the best of our knowledge, the only vehicles ever fitted with factory exo-cages are the Defender series built by Land Rover. Exo-cages offer some passenger safety but are generally added to a vehicle for body protection. They also work very well on tall or longer-wheelbase vehicles. The theory is that the longer the vehicle, the smaller the turning radius. The taller the vehicle, the more it will lean into obstacles, hence the need for additional body protection in tight spaces like narrow canyons.
Just about every exo-cage on the trail is custom-built, and they all serve the same purpose: to protect the vehicle's body panels and offer additional driver and passenger safety. The cages work! Notice that the front driver-side corner of the exo-cage is well worn, yet the fender is perfectly straight. | 
This is a fully functional cage incorporating an exo-cage on a well-used trail vehicle. The important thing to remember when building or ordering a cage is interior crossmembers. The crossmembers will keep the cage from collapsing in on itself in the event of a rollover. | 
Although there are millions of different configurations of rollcages, this is typically what you will find on the interior of a vehicle. The cages are stout, offer full protection, and usually are built so the factory hard top or soft top can be installed over them. |
Steel & Mass
If you are going to build or add a fully functional rollcage or exo-cage to your vehicle, you will be adding hundreds of pounds of weight and rolling resistance. A full interior rollcage with the addition of an exo-cage can add 200 to 500 pounds. Be prepared for a dramatic drop in fuel economy and performance. Also, keep in mind that the additional weight may take its toll on your suspension, requiring different spring rates, new shocks, or the revalving of your shocks.
Exo-cages work great in tight notches. Check out how the cage and integrated rocker guard protect the full side of the vehicle. | 
A properly designed cage includes well-placed grab handles that face inwards. If the vehicle were to roll or flop on its side, the occupants have a safe place to quickly grab without getting their hands crushed. It's also important to gusset the major connection and stress points of the rollcage. Taking a few minutes to fab a gusset or handle is well worth the possibility of saving a limb, fingers, or a life. | 
If a trail rig isn't running doors, we highly recommend interior driver and passenger door protection. It's not uncommon for people to be injured by obstacles protruding into the vehicle during a roll or a flop. |
What to Use
The two types of steel used for rollcages and exo-cages are 4130 chromoly and DOM (drawn over mandrel) steel tubing. Welded-seamed tubing is not recommended. Tubing sizes will range anywhere from 1 to 2 inches. Chromoly is a high-strength alloy steel that contains chromium and molybdenum. It's a misconception that chromoly is lighter than DOM. Since it is stronger, smaller diameters of chromoly can be used. For example; 0.090-inch-wall chromoly has about the same strength as 0.120-inch-wall DOM tubing. When chromoly is welded, great care should be taken, otherwise it can become cracked and brittle. If you haven't welded chromoly before, consult a professional before attempting to build a cage that is there to potentially save your life. DOM steel tubing is a lot easier to work with than chromoly and is about half the price. A cage built with DOM tubing-properly welded, gusseted, and constructed-should be safe and strong enough for any four-wheel build. Quickly quenching chromoly or DOM steel can cause cracking and lamellar tearing. Both metals should be allowed to air-cool. Chromoly tubing thicker than 0.120-wall inch should be heat-treated after welding.
Bolt-in rollcages like this sport cage from Rockhard 4x4 (www.rockhard4x4parts.com) offer good protection and are relatively easy to install. The company's cages utilize the factory Jeep rollbar but add rigidity and strength to it. The 1/2-inch-thick clamps not only hold everything together securely, but they look cool too. For maximum safety and protection, make sure any rollcage you decide to use is securely welded or bolted to the frame of the vehicle. | 
When building a rollcage make sure you notch the tubing properly. This will make the joint and weld stronger. Believe it or not, we have occasionally run across a homemade cage in which the tubing isn't notched, or notched enough. The huge gaps between the two pieces of tubing are filled with enough weld puddles to create another cage! | 
These weld-in, interlocking tube clamps from Camburg Engineering (www.camburg.com) are a great addition to exo-cages in noncritical areas. They work well around components that need to be removed for maintenance or repair. Over-the-hood or engine-compartment crossmembers are a perfect location for tube clamps. |
Cool Stuff
We have seen some pretty cool rollcages manufactured and custom built over the years. We like to think of a good rollcage builder as a fine artisan. Whether you are buying a cage or building your own, we highly recommend you do your research and choose wisely.