UCI CYCLING REGULATIONS  1.3.020 For road, track and for cyclo-cross competitions, the frame of the bicycle shall be of a  traditional pattern, i.e. built around a main triangle. It shall be constructed of straight or  tapered tubular elements (which may be round, oval, flattened, teardrop shaped or  otherwise in cross-section) such that the form of each element except the chain stays  and the seat stays encloses a straight line. The elements of the frame shall be laid out  such that the joining points shall follow the following pattern: the top tube (1) connects  the top of the head tube (2) to the top of the seat tube (4); the seat tube shall connect  to the bottom bracket shell; the down tube (3) shall connect the bottom bracket shell to  the bottom of the head tube. The rear triangles shall be formed by the chain stays (6),  the seat stays (5) and the seat tube (4) with the seat stays anchored to the seat tube at  points falling within the limits laid down for the slope of the top tube. (See diagram  «Shape (1)»). The seat post shall comply with the dimensional restrictions that apply to  the seat tube and may be attached to the frame anywhere on the seat tube and/or top  tube. (See diagram «Shape (2)»). The maximum height of the elements shall be 8 cm and the minimum thickness 1 cm.  The minimum thickness of the elements of the front fork shall be 1 cm; these may be  straight or curved (7). (See diagram «Shape (1)»).  The top tube (1) may slope, provided that this element fits within a horizontal template  defined by a maximum height of 16 cm.  The effective width of the head tube zone may not exceed 16 cm at the narrowest point  between the inner join of the top tube and down tube and the front of the box for the  head tube. Additional frame components can be added between the head tube and the handlebar  stem. These must be inside the dimension of the head tube box.  Isosceles compensation triangles with two 8 cm sides are authorized at the joints  between frame elements except at the joints between the chain stays and seat stays  where triangles are not authorised (See diagram «Shape (3)»).  (text modified on 07.06.00; 01.01.05; 01.02.12; 01.01.16; 01.01.21)  E0221  GENERAL ORGANISATION OF CYCLING AS A SPORT  63 