CRANK ARM FOR BICYCLE

PROBLEM TO BE SOLVED: To provide a right side crank arm for a bicycle with front gears mounted thereon in which the strength is not impaired, and the weight is reduced. SOLUTION: In the crank arm A for bicycle, an intermediate arm part 1, a base end boss part which is provided on one end part in the longitudinal direction of the intermediate arm part and fitted to a crank shaft of a bicycle, a tip boss part 3 which is provided on the other end part in the longitudinal direction of the intermediate arm part with a pedal fitted thereto, and a gear mounting part having a plurality of fingers 41a-41e radially extending at equal intervals from the base end boss part 2 with the axis thereof as a center and with front gears 6a-6c mounted thereon are integrally provided. In addition, in a pair of fingers adjacent to both sides of the intermediate arm part out of the plurality of fingers, the ends thereof are integrated the base ends of the intermediate arm part. A recessed part having a first part disposed in a longitudinal area integrated with the pair of fingers and a second part continuous from the first part to an intermediate part in the longitudinal direction of the intermediate arm part is formed in a back surface side of the intermediate arm part along the longitudinal axis of the intermediate arm part. COPYRIGHT: (C)2005,JPO&NCIPI