Minimum Dimensions( mm) 23.5. 45 x 2.5( 1.75in x 0.095in) or 50 x 2.0mm( 2.00in x 0.083in).
24. Single Seat Racing Cars
Material
24.1. The rollbar must be symmetrical about the lengthwise centre- line of the car and of minimum height 900mm measured vertically from the base of the cockpit or 920mm measured along the line of the Driver’ s spine from the bottom of the car seat. There must be at least one brace rearwards from the top of the rollbar at an angle not exceeding 60 ° with the horizontal, this brace must be the same diameter as the rollbar, if two braces are fitted to the tube the diameter may be reduced to 26mm x 2.5mm( 1in x 0.095in). Where two braces are fitted, they may be rearward or forward facing.
24.2. The width inside the roll-over bar main tubes must be 380mm minimum measured 600mm above the base of the seat. It must incorporate a crossbrace to restrain the driver’ s head and give rearward support. The top hoop radius must not be less than 100mm measured at the centre line of the tube.
24.3. Cold drawn seamless Carbon steel 350N / mm 2
Minimum dimensions( mm) 24.4. Vehicles up to 470kg:
38 x 2.5( 1.5in x 0.095in) or 40 x 2.0( 1.6in x 0.083in). 24.5. Vehicles 470kg and over
45 x 2.5( 1.75in x 0.095in) or 50 x 2.0( 2.0in x 0.083in).
25. Other Considerations
25.1. An effective rollbar must be fitted with its top edge not less than 50mm above the helmet of the normally seated driver. It must be wider than the driver’ s shoulders at that height. It must be constructed of good quality seamless steel tubing of minimum 35mm diameter and wall thickness of 2mm. It should have the top bar straight or slightly curved but no tubes meeting in an inverted‘ V’. It must be effectively braced to structural members.
25.2. Non-standard Vehicles are advised to fit a rollbar to the following minimum requirements.
a. Minimum height 72cm from the rear of the uncompressed seat cushion. b.
c.
d.
It must have minimum flat width of 38cm running into radiused corners and affording driver and if applicable Passenger equal protection.
It must be effectively mounted and braced to structural members forward and aft of the cockpit and not less than cockpit width.
It must be constructed of good quality seamless steel tubing of minimum 32mm diameter and wall thickness of 1.5mm.
26. ALL aluminium alloy Roll Cages are prohibited.
Motorsport UK 2025 National Competition Rules Version 11
Chapter 7 Appendix 3- Roll Over Protection Systems( ROPS) 259