A gear system based on variably expandable gears, where input from either or both an operator or a computer processor may induce selective radial expansion and contraction of at least one gear in a gear set. The computer processor may be programmed to establish and maintain a desired gear ratio, regardless of the various variable forces which may be encountered, permitting gear setting and adjustment to control a desired parameter, such as speed, revolutions-per-minute, and watts with minimal effort by the operator.

A method of operating a vehicle is provided. The vehicle includes: an engine; a throttle operator moveable by a driver; a throttle valve regulating airflow to the engine; a continuously variable transmission (CVT) operatively connected to the engine; at least one ground engaging member including at least one of: a wheel and a track; a piston operatively connected to a driving pulley of the CVT for applying a piston force to the driving pulley when actuated and thereby changing an effective diameter of the driving pulley; and a control unit for controlling actuation of the piston and the piston force. The method includes: determining a driven pulley speed of a driven pulley of the CVT; detecting an uphill stand condition indicative of the vehicle being stopped on an uphill; responsive to the detection of the uphill stand condition, controlling the piston force based on the driven pulley speed.

A method of operating a vehicle is provided. The vehicle includes: an engine; a throttle operator moveable by a driver; a throttle valve regulating airflow to the engine; a continuously variable transmission (CVT) operatively connected to the engine; at least one ground engaging member including at least one of: a wheel and a track; a piston operatively connected to a driving pulley of the CVT for applying a piston force to the driving pulley when actuated and thereby changing an effective diameter of the driving pulley; and a control unit for controlling actuation of the piston and the piston force. The method includes: determining a driven pulley speed of a driven pulley of the CVT; detecting an uphill stand condition indicative of the vehicle being stopped on an uphill; responsive to the detection of the uphill stand condition, controlling the piston force based on the driven pulley speed.

Automatic transmission system for a bicycle configured to automatically adjust a torque ratio in response to changing drive forces by one of either diametric expansion or diametric contraction of the pattern of sprockets. The automatic transmission including a drive chain, a plurality of sprockets, and one or more mechanisms providing a spring force bias which biases the pattern of sprockets toward one of either diametric expansion or diametric contraction. The plurality of sprockets is in a substantially evenly spaced radial pattern and is configured to engage with the drive chain which encompasses a periphery of the pattern of sprockets. The pattern of sprockets is configured to expand and contract about its centroid in unison, and 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 the other direction.

Automatic transmission system for a bicycle configured to automatically adjust a torque ratio in response to changing drive forces by one of either diametric expansion or diametric contraction of the pattern of sprockets. The automatic transmission including a drive chain, a plurality of sprockets, and one or more mechanisms providing a spring force bias which biases the pattern of sprockets toward one of either diametric expansion or diametric contraction. The plurality of sprockets is in a substantially evenly spaced radial pattern and is configured to engage with the drive chain which encompasses a periphery of the pattern of sprockets. The pattern of sprockets is configured to expand and contract about its centroid in unison, and 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 the other direction.

A ride-along vehicle may include both handles and foot rests each capable of providing power to the pump arm. An improved pumper arm and steering mechanism may include a pivot joint that is provided by rods, pins, or bolts attached to opposite sides of the pumper arm. The universal joint between the steering arm and the pumper arm can be aligned with the center of the pivot point to prevent rocking of the steering arm as the pumper arm is actuated.

A ride-along vehicle may include both handles and foot rests each capable of providing power to the pump arm. An improved pumper arm and steering mechanism may include a pivot joint that is provided by rods, pins, or bolts attached to opposite sides of the pumper arm. The universal joint between the steering arm and the pumper arm can be aligned with the center of the pivot point to prevent rocking of the steering arm as the pumper arm is actuated.

A bicycle chainring for engagement with a drive chain includes a plurality of teeth extending from a periphery of the chainring wherein roots of the plurality of teeth are disposed adjacent the periphery of the chainring. The plurality of teeth include a first group of teeth and a second group of teeth.

A bicycle chainring for engagement with a drive chain includes a plurality of teeth extending from a periphery of the chainring wherein roots of the plurality of teeth are disposed adjacent the periphery of the chainring. The plurality of teeth include a first group of teeth and a second group of teeth.

A snowmobile includes a frame, a tunnel, a seat, an endless track, at least one ski, a handlebar, a cowling defining an engine compartment, an engine, a continuously variable transmission (CVT) operatively connecting the engine to the endless track, and a pulley guard assembly disposed over at least a portion of the CVT. The CVT includes a primary pulley, a secondary pulley, and an endless flexible member operatively connecting the primary pulley to the secondary pulley. The pulley guard assembly is disposed between the CVT and a lateral side of the cowling, and defines an air inlet. The air inlet fluidly communicates with a space defined between the pulley guard assembly and the lateral side. In some implementations, the cowling defines an air inlet. In some implementations, an air duct fluidly connects the air inlet of the cowling to the air inlet of the pulley guard assembly.