PURPOSE: To improve durability and attain light weight by forming bottom bracket lug structure into a five-way joint reinforced in relation to a pedal axis by providing paddle like reinforcing parts at the root parts of a down tube fitting part, a seat tube fitting part and a chain stay fitting part.
CONSTITUTION: Seat lug structure is provided with paddle like reinforcing parts 4 at the root parts of a top tube fitting part 2 and a seat stay fitting part 3 so as to be formed into a four-way joint reinforced in relation to a seat tube axis 1. Head lug structure is provided with paddle like reinforcing parts 4 at the root parts of a top tube fitting part 6 and a down tube fitting part 7 so as to be formed into a three-way joint reinforced in relation to a head tube axis 5. Bottom bracket lug structure is provided with paddle like reinforcing parts 4 at the root parts of a down tube fitting part 9, a seat tube fitting part 10 and a chain stay fitting part 11 so as to be formed into a five-way joint reinforced in relation to a pedal axis 8.
ISHIMORI TAKUMI
NUMATA YOSHIHARU
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