Composite bicycle frame with y shaped tubular configuration

A bicycle comprising a front fork assembly, a seat assembly, a pedal axle support assembly, a rear wheel assembly a head tube sleeve for receiving said front fork assembly, a seat tube sleeve for receiving said seat assembly, and a bottom bracket tube sleeve for receiving said pedal support assembly;

• said bicycle being characterized in that if further comprising
• (a) a hollow slanted-Y-shaped front frame portion comprising:
• (I) a generally hollow common junction;
• (ii) a main tube connected between said heat tube sleeve and a middle portion of said generally hollow common junction in a slanted manner;
• (iii) an upper branch tube connected between said seat tube sleeve and an upper portion of said generally hollow common junction in a slanted manner;
• and
• (iv) a lower branch tube connected between said bottom bracket tube sleeve and a lower portion of said generally hollow common junction in a slanted manner;
• (b) a rear frame portion comprising:
• (I) an upper support paw connected between said seat tube sleeve and said rear wheel assembly via a first dropout, and a lower support paw connected between said pedal support assembly and said rear wheel assembly, said upper support paw and said lower support paw being disposed at opposite sides of said rear wheel assembly;
• and
• (ii) a generally hollow front junction for connecting between said main tube and said head tube sleeve, a generally hollow seat junction for connecting among said upper branch tube said seat tube sleeve and said upper support paw, and a generally hollow bottom bracket junction for connecting among said lower branch tube, said bottom bracket tube and said lower support paw;
• (c) wherein each of said main tube, said upper and lower branch tubes, said upper and lower support paws, and said junctions comprising at least a fibrous material impregnated with a synthetic resin, and said tubes, paws, and junctions being integrally united by overlapping edges of said resin impregnated fibrous material so as to form a unitary, bicycle frame.

A method for making slanted-Y shaped bicycle frame with reduced vertical rigidity for comfort and improved flexibility for drive chain assembly design comprising the steps of:

• (a) pre-forming a generally hollow common junction, a main tube, an upper branch tube, a lower branch tube, an upper support paw, a lower support paw, and a set of generally hollow front, seat tube and bottom bracket junctions;
• (b) using strip prepregs, which contain fibrous material impregnated with a synthetic resin, to connect said generally hollow common junction with said main tube, said upper branch tube, and said lower branch tube in a slanted-Y shape;
• (c) using said strip prepregs to connect said upper support paw with said seat tube junction and said upper branch tube such that said upper support paw will be disposed at one side of a rear wheel of said bicycle;
• (d) using said strip prepregs to connect said lower support paw with said bottom bracket junction and said lower branch tube such that said lower support paw will be disposed at another side of said rear wheel;
• (e) placing an inflatable bladder inside a hollow structure formed in steps (b) through (d);
• (f) placing said hollow structure obtained from step (e) into a bicycle frame mold;
• and
• (g) pumping air into said inflatable bladder while applying heat so as to cause said impregnated strips to be hardened.