초록 ▼

A rotatable sprocket assembly transmits force from a chain into rotation of a wheel on a bicycle. A plurality of sprocket segments having peripheral teeth are mounted on a pair of sprocket housings so that the combined periphery of the sprocket segments is substantially circular. The sprocket segmen

A rotatable sprocket assembly transmits force from a chain into rotation of a wheel on a bicycle. A plurality of sprocket segments having peripheral teeth are mounted on a pair of sprocket housings so that the combined periphery of the sprocket segments is substantially circular. The sprocket segments are slidable relative to the housing in a substantially radial direction so as to vary the diameter of the combined sprocket segments. Each sprocket segment is formed from a plurality of hinged subsegments, with each subsegment having a single tooth thereon. The sprocket segments of one housing overlap the adjacent sprocket segments on the other housing so that the pairs of overlapping teeth combine to effectively form a single tooth. The sprocket segments are movable angularly relative to the sprocket housings, so that in combination with the radial displacement of the sprocket segments, the total number of effective teeth on the sprocket assembly can be varied in increments of one tooth. The sprocket segments are retained in a desired radial position by a disengageable latch mechanism. A shift actuator contacts the latch mechanism to cause disengagement of the latch and angular displacement of the sprocket segments to a desired position. Movement of the shift actuator is accomplished manually or automatically through a motor and an electronic control system. The wheel and sprocket assembly are rotatable about a hub assembly which permits removal of the wheel from the bicycle without requiring removal of the sprocket assembly.

대표청구항 ▼

A device that automatically controls the gear selection of a multi-gear shifting mechanism of a bicycle, comprising: an electric motor engageable with the shifting mechanism so that rotation of said electric motor causes said shifting mechanism to shift from one gear to another gear, the motor opera

A device that automatically controls the gear selection of a multi-gear shifting mechanism of a bicycle, comprising: an electric motor engageable with the shifting mechanism so that rotation of said electric motor causes said shifting mechanism to shift from one gear to another gear, the motor operational in a first direction to cause said shifting mechanism to select a higher gear, said motor operational in a second direction to cause said shifting mechanism to select a lower gear; a transducer that generates a transducer output signal having a characteristic that varies in accordance with the rotation rate of one of the wheels of said bicycle; a strain gauge that detects the strain applied to said bicycle when being pedalled by a rider, said strain gauge providing a strain gauge output signal responsive to the detected strain; and an electrical circuit that receives said transducer output signal and said strain gauge output signal, and that generates a motor power signal to operate said electric motor, said electrical circuit comparing the characteristic of said transducer output with first and second ranges of characteristics for the currently selected gear, said first and second ranges of characteristics varying in response to said strain gauge output signal, said electrical circuit generating said motor power signal with a first polarity to operate said electric motor in said first direction to select a higher gear when said transducer output is within said first range of characteristics, said electrical circuit generating said motor power signal with a second polarity to operate said electric motor in said second direction to select a lower gear when said transducer output is within said second range of characteristics. A method of controlling an automatic shifting mechanism in a bicycle, comprising the steps of: generating a sequence of pulses having a pulse repetition rate responsive to the rotation speed of a bicycle wheel; counting the number of said pulses in said sequence in a predetermined amount of time; comparing said counted number of pulses with a predetermined range of pulses for the currently selected gear of said shifting mechanism; shifting said shifting mechanism to a selected one of a higher or a lower gear when said counted number of pulses is outside said predetermined range of pulses for the currently selected gear; measuring the strain applied to the rear wheel of said bicycle by a rider on said bicycle; and adjusting said predetermined range of pulses for the currently selected gear in response to the magnitude of said measured strain so that said shifting step occurs when said counted number of pulses is outside said adjusted predetermined range of pulses.