A pump-action mobility and exercise device may include a pumping arm attached to a foot slide. As the pumping arm is actuated, the foot slide moves forward and rearward in response to the pumping action. The foot slide can also be moved by a user's foot movement. The foot slide may be connected to a drive mechanism that selectively engages a chain or belt that loops around a drive wheel arranged on an axle of the vehicle. When the drive mechanism catches and moves the belt or chain in a forward direction, the axle rotates in a forward direction to drive the vehicle forward. A reverse mechanism may also be provided that selectively causes the drive mechanism to catch and drive the belt or chain in an opposite direction.

A bike includes a frame elongated in a longitudinal direction, a front fork rotatably engaged with a front wheel at a front end of the bike, a rear fork rotatably engaged with a rear wheel at a rear end of the bike, a handlebar supported for rotation at the front end of the frame for steering the bike, and a drive module configured to drive the rear wheel of the bike when operated selectively with power. The frame includes a down tube extending downward and rearward from the front end of the bike and a drive module enclosure formed at a second end of the down tube. The drive module enclosure defines a drive module receptacle that is open along the longitudinal direction of the bike. The drive module receptacle is sized to receive the drive module along the longitudinal direction of the bike.

A bike includes a frame elongated in a longitudinal direction, a front fork rotatably engaged with a front wheel at a front end of the bike, a rear fork rotatably engaged with a rear wheel at a rear end of the bike, a handlebar supported for rotation at the front end of the frame for steering the bike, and a drive module configured to drive the rear wheel of the bike when operated selectively with power. The frame includes a down tube extending downward and rearward from the front end of the bike and a drive module enclosure formed at a second end of the down tube. The drive module enclosure defines a drive module receptacle that is open along the longitudinal direction of the bike. The drive module receptacle is sized to receive the drive module along the longitudinal direction of the bike.

A chainring is disclosed herein. The chainring includes a front surface, a back surface, a center, and an outer diameter. The chainring has a thickness which varies from a lesser thickness at the outer diameter to a greater thickness nearer the center. The thickness of the chainring varying substantially the same on the front surface and the back surface such that the chainring is substantially symmetric about a plane dividing the front surface and the back surface along a direction normal to an axial direction of the chainring.

A chainring is disclosed herein. The chainring includes a front surface, a back surface, a center, and an outer diameter. The chainring has a thickness which varies from a lesser thickness at the outer diameter to a greater thickness nearer the center. The thickness of the chainring varying substantially the same on the front surface and the back surface such that the chainring is substantially symmetric about a plane dividing the front surface and the back surface along a direction normal to an axial direction of the chainring.

A foldable electric scooter and a manufacture method of the same. The foldable electric scooter includes a main body assembly, a front fork assembly located at the front end of the main body assembly, a rear fork assembly located at the rear end of the main body assembly, a telescoping plate assembly located on top of the front fork assembly and a handlebar assembly located on top of the telescoping plate assembly. The foldable electric scooter has a double headset design that increases a rake angle for more steering stability while still keeping the steering upright for an upright holding of the handlebars. The foldable electric scooter is manufactured by stamping of flat plate material.

A bicycle sprocket comprises sprocket teeth. The sprocket teeth include at least one first tooth and at least one second tooth. The at least one first tooth has a first radial-tooth height. The at least one first tooth has a first chain-engaging axial width which is smaller than a first distance defined between opposed outer link plates of a bicycle chain and which is larger than a second distance defined between opposed inner link plates of the bicycle chain. The first radial-tooth height is greater than the first chain-engaging axial width. The at least one second tooth has a second radial-tooth height. The at least one second tooth has a second chain-engaging axial width which is smaller than the second distance. The second radial-tooth height is greater than the second chain-engaging axial width. The first radial-tooth height is greater than the second radial-tooth height.

A bicycle sprocket comprises sprocket teeth. The sprocket teeth include at least one first tooth and at least one second tooth. The at least one first tooth has a first radial-tooth height. The at least one first tooth has a first chain-engaging axial width which is smaller than a first distance defined between opposed outer link plates of a bicycle chain and which is larger than a second distance defined between opposed inner link plates of the bicycle chain. The first radial-tooth height is greater than the first chain-engaging axial width. The at least one second tooth has a second radial-tooth height. The at least one second tooth has a second chain-engaging axial width which is smaller than the second distance. The second radial-tooth height is greater than the second chain-engaging axial width. The first radial-tooth height is greater than the second radial-tooth height.

A bicycle is equipped with a dual chain drive system having two cranksets symmetrically mounted on the rear section of an adapted and compact frame. The cranksets are located in close proximity to the rear wheel hub axle to enhance the energy efficiency, responsiveness and manoeuvrability of the bicycle.

A bicycle is equipped with a dual chain drive system having two cranksets symmetrically mounted on the rear section of an adapted and compact frame. The cranksets are located in close proximity to the rear wheel hub axle to enhance the energy efficiency, responsiveness and manoeuvrability of the bicycle.