A drive train for a human-powered vehicle comprises a drive unit, a sprocket arrangement, and a total gear range quotient. The drive unit includes a motor configured to impart propulsion to the human-powered vehicle. The sprocket arrangement is operatively coupled to the drive unit. The sprocket arrangement comprises a plurality of rear sprockets and a plurality of gear ratios respectively corresponding to the plurality of rear sprockets. The plurality of gear ratios includes a largest gear ratio and a smallest gear ratio. The total gear range quotient is obtained by dividing the largest gear ratio by the smallest gear ratio. The total gear range quotient is larger than 5.

Chain-rings sets for power transmission systems, where at least one of the chain-rings is formed by independent segments provided with axial displacement means, where the segmentation is optimum both for shifts to a bigger chain-ring or a smaller chain-ring through a relative configuration between chain-rings, especially between the teeth involved in the power transmission during the shift, that ensure a smooth shift, efficient in the power transmission and reducing as possible the friction and the wear of the components.

A drive train comprises a sprocket arrangement and a force-transmission coefficient. The sprocket arrangement includes a plurality of rear sprockets and a plurality of gear ratios respectively corresponding to the plurality of rear sprockets. The plurality of gear ratios includes a largest gear ratio and a smallest gear ratio. The sprocket arrangement includes at least one individual sprocket-space provided between two adjacent rear sprockets among the plurality of rear sprockets. The force-transmission coefficient is obtained by dividing a total gear range quotient by a total number of the at least one individual sprocket-space. The force-transmission coefficient is equal to or larger than 0.97 and is equal to or smaller than 1.36. The total gear range quotient is obtained by dividing the largest gear ratio by the smallest gear ratio.

The present invention relates to a bicycle chainring (1) for engagement with a drive chain provided with rollers, the bicycle chainring (1) comprising: a plurality of teeth (2, 3) extending radially from a periphery of the chainring (1), wherein the plurality of teeth (2, 3) comprises a plurality of narrow teeth (3) and a plurality of wide teeth (2), wherein each tooth (2, 3) comprises a front flank (5) and a rear flank (6) with respect to a drive direction (DD) and two opposing side surfaces (9), wherein at least one side surface (9) of each wide tooth (2) comprises a protrusion (7) extending therefrom in an axial direction of the chainring (1), wherein each protrusion (7) comprises a respective groove (8) arranged halfway between a top land (10) of the respective wide tooth (2) and a root circle (11) of the respective wide tooth (2), wherein the groove (8) extends throughout the protrusion (7) in a direction substantially parallel to the top land (10). The invention further relates to a bicycle comprising the of the invention chainring (1).

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 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.

Chain-rings sets for power transmission systems, where at least one of the chain-rings is formed by independent segments provided with axial displacement means, where the segmentation is optimum both for shifts to a bigger chain-ring or a smaller chain-ring through a relative configuration between chain-rings, especially between the teeth involved in the power transmission during the shift, that ensure a smooth shift, efficient in the power transmission and reducing as possible the friction and the wear of the components.

A transmission structure for a bicycle includes two opposite transmission units. Each of the transmission units includes a linear reciprocating pedaling mechanism, a transmission module which is in transmission connection with the linear reciprocating pedaling mechanism, and a resetting module connected with the transmission module. The transmission modules of the two transmission units are connected with a power output mechanism through a unidirectional transmission mechanism. The transmission module includes a first driven wheel and a first transmission gear configured to be coaxial with the first driven wheel. The resetting module includes a connecting piece and an elastic piece. The connecting piece is connected with the first transmission gear. The elastic piece is connected with the connecting piece.

A ride-along vehicle may include a guard that attaches to a bottom portion of a molded plastic body and covers a spring and chain assembly. The guard may also provide an attachment point for the spring through a hole in the guard. The guard may have a narrow portion that covers and helps retain the chain on a sprocket as well as a wider portion that covers the spring. 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.