World Tri Rules 5.2
l.) Fairings are prohibited. Fairings are defined as any devices or materials added, attached, or blended into the structure of the bicycle which have the effect of reducing the resistance to air penetration. Devices or materials (including duct tape)
added, attached, or blended into the structure of the bicycle that does not fundamentally alter or enlarge the general shape of the structure. . . are not affected by this rule;
IRONMAN Rules 5.03
(b) Protective screens, fuselages, fairings, or any other devices or materials (including duct tape) added or blended into the structure with the intent to reduce (or having the effect of reducing) resistance to air penetration are prohibited. Aerodynamic assemblies and protuberances on the head tube or elsewhere are prohibited.