Bicycle frame manufacture
View Patent ↗A bicycle frame is provided in which the head tube, top tube and down tube are constructed as a single structural unit with the ends of the top tube and down tube left open to allow for ease of molding.
1. A method of manufacture of a bicycle frame with
a top tube with a front end and a rear end,
a head tube with a top end and a lower end,
a down tube with a front end and a rear end,
a seat tube with a top end and lower end,
the front end of the top tube connected to the top end of the head tube,
the front end of the down tube connected to the lower end of the head tube,
the top tube and down tube diverging away from each another as they extend rearwardly from the head tube,
the rear end of the down tube coupled to the lower end of the seat tube,
the rear end of the top tube top connected to the top end of the seat tube,
the top tube, head tube, down tube and seat tube substantially forming a closed main frame loop,
the frame comprises a sub assembly molded simultaneously as a single piece comprising the top tube, the head tube and the down tube with the rear end of the top tube open providing access through the top tube to the top end of the head tube and with the rear end of the down tube open providing access through the down tube to the lower end of the head tube,
the method comprising:
molding the sub assembly,
manufacturing the remainder of the elements of the frame, and assembling the sub assembly and the remainder of the elements.
2. The method of claim 1 wherein the step of molding includes placing a preformed hollow element formed of uncured fibres reinforced composite materials to form the top tube, head tube and down tube in the mold cavity, placing the cores into the hollow element, constraining the hollow element between interior surface of the mold cavity and exterior surfaces of the cores while curing the resin by the application of heat.
3. The method of claim 2 wherein the cores are inflatable cores.
4. The method of claim 2 wherein the cores are solid cores with higher coefficients of thermal expansion than materials used in construction of the mold.
5. The method of claim 4 wherein the solid core is silicon.
6. The method of claim 4 wherein the solid core is rubber.
7. The method of claim 2 wherein the solid core is a material that self expands.
8. The method of claim 7 wherein the material is expanding foam.
9. The method of claim 1 wherein the step of molding includes placing a preformed hollow element formed of uncured fibres reinforced composite materials to form the top tube, head tube and down tube in the mold cavity, placing the cores into the hollow element, constraining the hollow element between interior surface of the mold cavity and exterior surfaces of the cores while curing the resin by the application of heat.
10. The method of claim 9 wherein the cores are inflatable cores.
11. The method of claim 9 wherein the cores are solid cores with higher coefficients of thermal expansion than materials used in construction of the mold.
12. The method of claim 11 wherein the solid core is silicon.
13. The method of claim 11 wherein the solid core is rubber.
14. The method of claim 9 wherein the solid core is a material that self expands.
15. The method of claim 14 wherein the material is expanding foam.
16. A method of manufacture of a bicycle frame with
a top tube with a front end and a rear end,
a head tube with a top end and a lower end,
a down tube with a front end and a rear end,
a seat tube with a top end and lower end,
the front end of the top tube connected to the top end of the head tube,
the front end of the down tube connected to the lower end of the head tube,
the top tube and down tube diverging away from each other and extend rearwardly from the head tube,
the rear end of the down tube coupled to the lower end of the seat tube,
the rear end of the top tube top connected to the top end of the seat tube,
the top tube, head tube, down tube and seat tube substantially forming a closed main frame loop,
the frame comprises a sub assembly molded simultaneously as a single piece comprising the top tube, the head tube and the down tube with the rear end of the top tube open providing access through the top tube to the top end of the head tube and with the rear end of the down tube open providing access through the down tube to the lower end of the head tube;
wherein the sub assembly is molded with a first core extending via the open top end of the head tube into the interior of the head tube and out the lower end of the head tube, a removable second core extending via the open rear end of the top tube into the interior of the top tube and to the front end of the top tube and with a removable third core extending via the open rear end of the down tube into the interior of the down tube and to the front end of the down tube, the method comprising:
molding the sub assembly,
manufacturing the remainder of the elements of the frame, and assembling the sub assembly and the remainder of the elements.
17. The method of claim 16 wherein the first core is removable.
18. The method of claim 17 wherein the first core extends into the front end of the top tube and the front end of the down tube.
19. The method of claim 16 wherein the first core extends into the front end of the top tube and the front end of the down tube.