Abstract
Application of tapered handlebars using high strength aluminum alloys is effective to weight reduction and high texture appearance. However, due to the influence of Cu contained as a strengthening element, the extrusion productivity of material pipe was low, and the cost was high. Therefore, an alloy in which the addition amount of Cu was suppressed and which was strengthened by addition of Zn was selected. In addition, stress corrosion cracking resistance was secured by optimizing manufacturing conditions. As a result, the weight was reduced by 20% and the cost was reduced by 30%．
