1. Field of the Invention
The present invention relates to a bicycle and more particularly to such a front fork for a bicycle, which has strong structure and light weight.
2. Description of the Related Art
A conventional front fork for a bicycle is made of metal. Recently, the bicycle is developed towards reducing its weight and adopts fiber reinforced material. As shown in FIG. 1, the front fork 1 is made of carbon fiber reinforced resin. The front fork 1 is manufactured by winding multiple layers of pre-pregs into two elongated tubes 2, placing the elongated tubes 2 into a die 3 and winding pre-pregs 4 around predetermined position for enhancement, inflating the elongated tubes 2 to make the elongated tubes 2 abut on an inner wall of the die 3, and curing the elongated tubes 2 and the pre-pregs 4 to form the front fork 1.
The front fork 1 has an upright tube 5 and two arms 6 extending from a bottom of the upright tube 5. As shown in FIG. 1, the two arms 6 each consist of an elongated tube 2, which does not has enough structural strength. It's easy to break, especially when the arms 6 encounter lateral stress. If the quantity of the pre-pregs used in the front fork 1 is increased for enhancing the structural strength, the weight of the product is unintentionally increased. Therefore, there is always a problem as to how to reduce the weight of the front fork and increase the structural strength at the same time.