A roll cage is a specially constructed frame built in or around the cab of a vehicle to protect occupants from being injured in an accident, particularly in the event of a roll-over. There are many factors to consider when selecting a roll cage set-up for a specific vehicle, including but definitely not limited to:

     – The material choice and strength

     – The load placed on the cage, chassis, and attachment points

     – Yield stress, the pressure level a material can take before it starts to bend and not return to its original shape after the force is removed

     – Ultimate stress, the pressure level that will fracture a material. This will typically result in the structure failing as a safety device.


There are three basic material choices, including mild steel tubing, DOM steel tubing, and 4130 chromoly steel tubing, each with unique characteristics. The size of the tubing to be used is determined by the weight of the vehicle.

– Mild Steel Tubing:

     – Made from sheet that is rolled and welded

     – Typically made of 1010 alloy or higher

     – Not as strong as the others

     – Acceptable with proper design

     – Tendency to bend before breaking


– DOM Steel Tubing

     – Manufactured and welded similar to mild steel tubing

     – Typically made of alloy 1018 and up to 1026

     – The higher the number, the higher the carbon content and the stronger the steel.

     – DOM means Drawn Over Mandrel

     – DOM is a process, not an alloy or type of steel

     – DOM process “trues” the tube and hides the weld, resulting in more accurate dimensions

     – DOM is considered the best choice for most builders since its is the strongest mild steel option and does not require the expertise of 4130 methods


– 4130 Chromoly Steel Tubing

     – Typically a true seamless tube

     – Chromium and molybdenum added for strength

     – Allows for a lighter design, with a thinner wall as strong as a thicker wall mild steel tube

     – Requires heat treating after welding to achieve maximum strength


There are often rules and regulations for roll bar/cage set-ups if competing in certain racing series. For example, NHRA states that a vehicle running a 10.99 second quarter mile or faster is required to have a roll cage rather than a hoop roll bar. For OEM-frame cars, the roll bar/cage must be attached to the frame. In unibody cars (most late model cars), a 6-inch square steel plate measuring 1/8″ thick must be welded to the floor as a base for each bar that makes its point of contact inside the car.

As a fusion of form and function, a roll cage serves the ultimate purpose of safety and performance. In the case of an accidental rollover or a high g-force turn in or out of a corner, the roll cage has played an elemental role in the past and future development of racing.