8. Backstays
8.1. These are compulsory and must be attached near the roofline and near the top outer bends of the main rollbar on both sides of the car. They must make an angle of at least 30 ° with the vertical, must run rearwards and be straight and as close as possible to the interior side panels of the bodyshell. Their materials specification, diameter and thickness must be as defined in Art. 18.1. Forward facing stays are permitted if an angle of 30 ° cannot be achieved with Backstays providing they do not unduly impede Driver and Co-Driver access to the Vehicle.
8.2. Their mountings must be reinforced by plates. Each backstay should be secured by bolts having a cumulative section area at least two thirds of that recommended for each rollbar leg mounting in Art. 7 above and with identical reinforcement plates of a least 60cm 2 area( see Appendix 13 Diagram 22). A single bolt in double shear is permitted providing it is of adequate section and strength( see Appendix 13 Diagram 29) and provided that a bush is welded into the backstay.
8.3. The mounting foot or backstay may alternatively be welded directly to the bodyshell / reinforcement plate in accordance with Appendix 13 Diagram 22.
9. Diagonal Members
9.1. At least one diagonal member must be fitted. Their location must be in accordance with Appendix 13 Diagram 14 or15 and they must be straight. The combination of several diagonal members is permitted.
9.2. Where two diagonals in the form of a cross are used at least one of the diagonals must be a single piece tube.
9.3. The attachment points of the diagonal members must be so located that they cannot cause injuries. They may be made removable but must be in place during Events. The lower end of the diagonal must join the main rollbar or back-stay not further than 100mm from the mounting foot. The upper end must join the main rollbar not further than 100mm from the junction of the backstay joint, or the backstay not more than 100mm from its junction with the main rollbar.
9.4. They must comply with the minimum specification set out in Art. 18.1. A diagonal member fixed to the bodyshell must have reinforcement plates as defined in Art. 8 above.
10. Optional Reinforcement of ROPS
10.1. The diameter, thickness and material of reinforcements must be as defined in Art. 18.1. They must be either welded in position or installed by means of demountable joints. Reinforcement tubes must not be attached to the bodyshell.
11. Transverse Reinforcing Members:
11.1. The fitting of two transverse members as shown in Appendix 13 Diagram 18 is permitted. The transverse member fixed to the front rollbar must not encroach upon the space reserved for the Driver or Co-Driver. It must be placed as high as possible but its lower edge must not be higher than the top of the dashboard.
12. Doorbars( for side protection):
12.1. Longitudinal members must be fitted at each side of the Vehicle( see Appendix 13 Diagram 18 and 21). They may be removable.
12.2. The side protection must be as high as possible but not higher than one half of the total height of the door aperture measured from its base.
12.3. Where two members in the form of a cross are used, at least one of the members must be a single piece tube.
12.4. Where configuration Appendix 13 Diagram 21 is used a reinforcing gusset must connect the tubes along the horizontal length.
Motorsport UK 2025 National Competition Rules Version 11
Chapter 7 Appendix 3- Roll Over Protection Systems( ROPS) 252