Precision suspension fork for bicylces

  • US 5,470,090 A
  • Filed: 09/07/1993
  • Issued: 11/28/1995
  • Est. Priority Date: 09/07/1993
  • Status: Expired due to Fees
First Claim
Patent Images

1. A suspension fork for mounting to a front wheel axle of a bicycle, comprising:

  • a. a steerer having an upper end and a lower end;

    b. a crown having a body with a central bore and two opposite end bores, said lower end of said steerer being press fit into the central bore of the crown;

    c. two parallel fork legs each having an upper end extending through a respective one of said end bores of said crown and secured to said crown, and a lower end attached to said front wheel axle, each fork leg further having a telescoping suspension system with an upper leg and a lower leg slidably engaged to each other;

    d. a brake arch having a cross-portion with a rim brake cable receiver and two leg-portions;

    e. a brake flange coupled to each one of said two fork legs for mounting one of said two legs of said brake arch and a rim brake post in a spaced apart relationship;

    f. said telescoping suspension system comprising an outer tube which is said lower leg, the outer tube having an elongated hollow tubular body with an upper end and a lower end, the upper end being press fit with said brake flange, and the lower end being said lower end of said telescoping suspension system;

    g. said telescoping suspension system further comprising an inner tube which is said upper leg, the inner tube having an elongated hollow tubular body with an upper end and a lower end, the body having a sidewall with reduced thickness tapered from the upper end toward the lower end, the upper end being said upper end of said telescoping suspension system, and the inner tube slidably engaged to said outer tube with the lower end of the inner tube sliding inside said outer tube;

    h. said telescoping suspension system further comprising a compression rod, the compression rod having an elongated body with an internal bore, the body having an upper portion with an upper end and a lower portion with a lower end, the compression rod further having an integral compression flange positioned at the upper end, an integral rebound flange positioned at the upper portion and spaced apart from the upper end of the compression rod, and a detachable positive stop clip attached at the lower portion and spaced apart from the lower end of the compression rod, the compression rod slidably engaged to said inner tube with the upper portion of the compression rod sliding inside said inner tube, and the lower end of the compression rod coupled to said lower end of said outer tube;

    i. an adjuster assembly having a cap mounted on said upper end of said inner tube, a spool slidably engaged with said cap, an adjuster screw threadedly engaged with the spool, a knob accessible from outside of said upper end of said inner tube for rotating the adjuster screw to drive the spool, and an elastomer adapter attached to the spool;

    j. a compression elastomer assembly having an elastomer rod, the elastomer rod having an upper end secured to said elastomer adapter of said adjuster assembly and a lower end received by said internal bore of said compression rod, the compression elastomer assembly further having a multiplicity of compression elastomers placed on the elastomer rod in series and partitioned by a multiplicity of elastomer washers, and positioned inside said inner tube between said elastomer adapter of said adjuster assembly and said compression flange of said compression rod to provide an easy fine-tuning of a preload on said compression elastomers by turning said knob of said adjuster assembly, and also to provide a compressive damping force when said outer and inner tubes are compressed from a balanced condition;

    k. a rebound elastomer assembly having at least two rebound elastomers placed on said compression rod and positioned inside said inner tube and between said rebound flange and said lower end of said inner tube to provide a rebound damping force when said outer and inner tubes are extended from said balanced condition;

    l. a second stage elastomer assembly having at least one positive stop elastomer placed on said compression rod and positioned outside said inner tube and between said lower end of said inner tube and said positive stop clip to provide a secondary compressive damping force when said inner tube travels into said outer tube excessively; and

    m. means for converting said suspension fork from a standard travel configuration to a long travel configuration, including one of said at least two rebound elastomers, which can be removed from said compression rod, and an additional compression elastomer, which can be added to said compression elastomer assembly, so that said inner and outer tubes can balance at an extended position to increase a compressive travel distance of said inner tube;

    n. whereby said suspension fork provides not only compressive but also rebound damping, and positive stop damping, and further provides fine-tuning ability of said preload, and easy conversion between said standard and long travel configurations.

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