Front gear for bicycles

  • US 4,453,924 A
  • Filed: 03/25/1982
  • Issued: 06/12/1984
  • Est. Priority Date: 03/30/1981
  • Status: Expired due to Fees
First Claim
Patent Images

1. A front gear for a bicycle comprising a gear main body made of plastics and a metal core embedded in the gear main body;

  • the gear main body being in the form of an integral molding of plastics including a plurality of support arms arranged radially of the axis of the main body, an inner annular portion connecting together radially inward base ends of the support arms, an outer annular portion connecting together radially outward ends of the support arms and a sprocket wheel formed at the outer annular portion, the sprocket wheel and the outer annular portion being integrally joined together at an inner periphery of the outer annular portion and being arranged in succession axially thereof as spaced apart from one another so that the outer annular portion serves as a chain guard;

    the metal core including a boss having a serrated bore for a crankshaft to fit in and ribs integral with the boss and extending radially from the boss in corresponding relation to the support arms, each extended end of the ribs terminating at an intermediate portion of the support arms, at least one of the ribs being formed with a positioning hole, the ribs being embedded in the support arms of the gear main body, the boss being embedded in the inner annular portion of the gear main body at only an outer peripheral portion of the boss, while an inner peripheral portion of the boss being exposed to which an end of the metal crank shaft is to be crimped after insertion into the boss;

    at least one of the support arms being formed with an opening and register with the positioning hole.

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