Frame assembly for a motorcycle

A frame assembly for a motorcycle, the frame assembly comprising:

• a head pipe for supporting a front wheel suspension at a front end of the motorcycle,
• a unitary leading frame portion attached to and extending rearwardly from said head pipe, and
• a rear frame portion for supporting a rear wheel suspension, said rear frame portion extending downwardly from a rear part of said leading frame portion, wherein
• the frame assembly comprises a first component part and a second component part, said first and second component parts arranged serially in a front-to-rear direction of the motorcycle, the first and second component parts being cast from an aluminum alloy;
• wherein the first component part comprises the head pipe and the leading frame portion, and the second component part comprises the rear frame portion,
• wherein the leading frame portion comprises a small section portion which provides a part of the leading frame portion having the smallest sectional area, the small section portion disposed medially in the longitudinal direction of the leading frame portion, and
• wherein the first and second component parts are coupled together at a portion of said frame assembly located behind said small section portion, wherein the first component part is joined to said second component part at a coupling portion, and the cross sectional area of the coupling portion is greater than the cross sectional area of the small section portion.

A frame assembly for a motorcycle, the frame assembly comprising:

• a head pipe for supporting a front wheel suspension at a front end of the frame assembly,
• a unitary leading frame portion integrally attached to and extending rearwardly from said head pipe, said unitary leading frame portion formed as a closed rectangular tube when viewed in cross-section, and
• a rear frame portion for supporting a rear wheel suspension, said rear frame portion extending substantially downwardly from a rear part of said leading frame portion, the rear frame portion having recessed portions opened in leftward and rightward directions and comprising integrally formed pivot support sleeves projecting in the leftward and rightward directions, such that the rear wheel suspension is supported by the pivot support sleeves;
• wherein
• said frame assembly is cast from an aluminum alloy and comprises three component parts arranged serially in the front-rear direction of the motorcycle;
• and
• said leading frame portion comprises a small section portion which provides a part of the leading frame portion having the smallest sectional area, the small section portion disposed at a medial part, in the longitudinal direction, of the leading frame portion, and the two rear-side component parts of said three component parts are coupled on the rear side relative to said small section portion,
• wherein a coupling portion is formed between the three component parts.

A frame assembly for a motorcycle, the frame assembly comprising:

• a head pipe for supporting a front wheel suspension at a front end thereof,
• a unitary leading frame portion extending rearwardly from said head pipe, said unitary leading frame portion formed as a closed rectangular tube when viewed in cross-section, and
• a rear frame portion for supporting a rear wheel suspension, said rear frame portion extending substantially downwardly from a rear part of said leading frame portion, the rear frame portion having recessed portions opened in leftward and rightward directions and comprising integrally formed pivot support sleeves projecting in the leftward and rightward directions, such that the rear wheel suspension is supported by the pivot support sleeves;
• wherein said frame assembly is cast from an aluminum alloy, and comprises two component parts joined serially in a front-to-rear direction of the motorcycle,
• wherein a coupling portion is formed between a first component part and a second component part.

A frame assembly for a motorcycle, the frame assembly comprising:

• a head pipe for supporting a front wheel suspension at a front end of the frame assembly,
• a unitary leading frame portion attached to and extending rearwardly from said head pipe, and
• a rear frame portion for supporting a rear wheel suspension, said rear frame portion extending substantially downwardly from a rear part of said leading frame portion, wherein
• said frame assembly is cast from an aluminum alloy and comprises three component parts arranged serially in the front-rear direction of the motorcycle;
• and
• said leading frame portion comprises a small section portion which provides a part of the leading frame portion having the smallest sectional area, the small section portion disposed at a medial part, in the longitudinal direction, of the leading frame portion, and the two rear-side component parts of said three component parts are coupled on the rear side relative to said small section portion,
• wherein said unitary leading frame portion is bisected in the front-rear direction of the motorcycle body.