6 inches as done for the tube portion preforms and one flap 32a is applied onto the outside of the preform of seat tube portion 8 and a second flap 32b is placed inside of this preform between its inner surface and the outer surface of seat tube insert 14 as shown in fig7 in order to maximize compaction and structural strength in this area an expandable fiber reinforced structural epoxy foam is placed inside of the seat stay socket forming connector tube section 32 and a core pin 34 is inserted into the free end of the connector tube section 32 to define the inside wall of the seat stay socket as with the other inserts 10 12 insert 14 may be wrapped with a single ply of prepreg material however in this case due to the presence of tube 14a such a ply would not be wrapped so as to completely cover the outer surface of the insert 14 also as was the case in forming the other corner sections 9 11 a quantity of expandable fiber resin reinforced epoxy foam is applied to fill out the corner area and also serves to protect the bladder 22 against damage by the metal insert when it is expanded.