Abstract: Methods for making an aluminum alloy bicycle frame and for making tubes for such frames including use of an aluminum alloy containing about 0.5 to 1.3% magnesium, about 0.4 to 1.2% silicon, and about 0.6 to 1.2% copper and preferred practices for making extruded and drawn tubing of the alloy and making bicycle frames from the tubing. The preferred practices include extrusion temperature control and other aspects of extrusion and drawing.

Abstract: A method of providing an efficiently running internal combustion engine including the steps of operating an engine at a constant rpm while increasing the torque load on the engine, measuring the torque value at predetermined intervals of the torque load to obtain a brake mean effective pressure for each of the intervals, and measuring the fuel consumption at the predetermined intervals. The common log of the brake mean effective pressure is plotted against the common log of the fuel consumption for each interval to obtain a straight line curve (10) which extends linearly with a constant first slope to a D-point coordinate (16) after which it continues at a different second slope. A straight line extension (20) is plotted having the first slope and extending upwardly from the D-point coordinate (16).