| 摘要 |
A light weight bicycle frame has open section, e.g. I section, parts cast in a light weight metal or alloy, preferably a magnesium alloy. A frame consists of an upper bar, and a lower bar, a saddle stem, a head, and rear forks. The bars are of I section and the saddle stem is of U section merging into or taking a tubular section receiving a saddle support tube. A structural bridge of I section interconnects the bars. The lower bar joins the saddle stem at a point intermediate the ends thereof and above the bearing for a crank wheel.
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