Automatic transmission system for a bicycle

An automatic transmission system for a bicycle comprising:

• a drive chain;
• a rear wheel hub;
• and
• a rear mechanism configured to transfer drive forces between the drive chain and the rear wheel hub, the rear mechanism comprising:
• a plurality of sprockets in a substantially evenly spaced radial pattern proximal to a common plane and substantially equidistant from the pattern's centroid, each of the plurality of sprockets comprising a rotational center, wherein the plurality of sprockets are configured to engage with the drive chain, wherein the drive chain partially encompasses a periphery of the pattern of sprockets, wherein the pattern of sprockets is configured to expand and contract about its centroid in unison, and wherein each of the plurality of sprockets is restricted from rotating in a direction which enables a transfer of drive forces in propelling the bicycle forward but is able to rotate in an opposite direction;
• one or more springs providing a spring force bias which biases the pattern of sprockets toward diametric contraction;
• a first plate having a central axis;
• a second plate, rotatable relative to the first plate about a common axis;
• a plurality of linkages arranged in a radial pattern about the first plate's central axis, each linkage comprising:
• an arm connected to the first plate at a first pivotable linkage connection,
• a link connected to the arm at a second pivotable linkage connection, the link also connected to the second plate at a third pivotable linkage connection, and
• a fourth pivotable linkage connection between the first plate and the second plate, wherein the fourth pivotable linkage connection is a common connection within each of the plurality of linkages,
• wherein the plurality of linkages actuate in unison as the first plate and second plate counter-rotate relative to each other, wherein each of the plurality of sprockets is connected to one of the plurality of linkages, wherein a radial distance from the first plate's central axis to the rotational center of each sprocket corresponds to an amount of actuation of each of the plurality of linkages, wherein each of the plurality of linkages actuates in an outward direction expanding the radial pattern of sprockets toward the drive chain as drive forces increase, and wherein each of the plurality of linkages actuates in an inward direction contracting the radial pattern of sprockets away from the drive chain as drive forces decrease;
• and
• one or more dampers configured to slow inward actuation of each of the plurality of linkages as drive forces decrease,
• wherein the rear mechanism is configured to automatically adjust a torque ratio in response to changing drive forces by one of either diametric expansion of the pattern of sprockets as drive forces increase or diametric contraction of the pattern of sprockets as drive forces decrease.