A junction for the head tube of a bicycle frame with top tube and down tube members is fabricated in such a way that the top tube and down tube members are jointed. The method of mitering the top tube and down tube members to form the requested joint is cutting off a portion of walls of both the top tube and down tube members at the head ends to form a miter joint. The method of mitering provides for optimum contact area and ease of manufacturing, especially for tubes with non-traditional cross-sectional shapes.
In a frame structure of a small vehicle, an abutting surface abutting against a first frame member is provided on a second frame member constituting a part of a vehicle frame together with the first frame member. The second frame member is welded to the first frame member by an outer periphery of the abutting surface. The two frame members constituting a part of the vehicle frame are also welded together by the outer periphery of the abutting surface formed on the second frame member so as to abut against the first frame member. This achieves a decrease in the size and weight of the second frame member while sufficiently ensuring joining strength thereof. An opening portion open to an abutting surface is provided in a second frame member to expose a part of a first frame member. The second frame member is welded to the first frame member by a periphery of the opening portion.
A head tube for a bicycle frame that accommodates oversized frame tubing and the use of a standard sized head set. Preferably, the head tube includes a body defining a pair of lateral extensions that cooperate with the body to define an outer surface configured to receive at least a portion of a frame tube. In addition, preferably, the head tube defines a wall thickness that is thicker at the bottom of the head tube than the thickness at the top of the head tube. In addition, preferably, the wall thickness is greater at both of the top and the bottom of the head tube than the wall thickness of the middle of the head tube. Preferably, in at least a portion of the head tube, the wall thickness is thicker in a forward side than the thickness in a rearward side.
A bicycle including a frame having a main frame portion and an articulating frame portion pivotally mounted to the main frame portion and carrying a rear wheel of the bicycle. A shock absorber preferably is operably connected between the main frame portion and the articulating frame portion. Preferably, the top tube and down tube of the main frame contact one another for a distance extending rearwardly from the head tube of the main frame. In one arrangement, the down tube has a non-circular cross-sectional shape.
