A pedal crank drive having a pedal crank (12) and a chain ring (14), which can be connected to each other in a rotationally fixed manner to form a unit (10), the unit (10) having a spindle hole (16) for a bottom bracket spindle. The chain ring (14) has a first connecting contour (18) and the pedal crank (12) has a second connecting contour (20), wherein the connecting contours (18, 20) can be fitted into one another in an assembly position, and the pedal crank (12) and the chain ring (14) can be rotated relative to one another around the spindle hole (16) to a stop position in which the stop surfaces (22, 24) of the pedal crank (12) and the chain ring (14) abut against each other.

A pedal crank drive having a pedal crank (12) and a chain ring (14), which can be connected to each other in a rotationally fixed manner to form a unit (10), the unit (10) having a spindle hole (16) for a bottom bracket spindle. The chain ring (14) has a first connecting contour (18) and the pedal crank (12) has a second connecting contour (20), wherein the connecting contours (18, 20) can be fitted into one another in an assembly position, and the pedal crank (12) and the chain ring (14) can be rotated relative to one another around the spindle hole (16) to a stop position in which the stop surfaces (22, 24) of the pedal crank (12) and the chain ring (14) abut against each other.

One variation of a bicycle propulsion system includes: hub adapter configured to install on a rear axle of a bicycle and apply torque to the rear axle through a rear disk brake of the bicycle; a first rotor element; a second rotor element cooperating with the first rotor element to form a circular outer drive surface around the rear disk brake; a set of hub adapter brackets configured to engage the hub adapter; a chassis configured to transiently couple to a frame element of the bicycle; a rotor retainer arranged on the chassis and configured to locate the first rotor element and the second rotor element relative to the chassis; a motor mounted to the chassis; and a drive assembly arranged on the chassis and configured to transfer torque output by the motor into the circular outer drive surface to rotate the rear axle via the set of hub adapter brackets.

One variation of a bicycle propulsion system includes: hub adapter configured to install on a rear axle of a bicycle and apply torque to the rear axle through a rear disk brake of the bicycle; a first rotor element; a second rotor element cooperating with the first rotor element to form a circular outer drive surface around the rear disk brake; a set of hub adapter brackets configured to engage the hub adapter; a chassis configured to transiently couple to a frame element of the bicycle; a rotor retainer arranged on the chassis and configured to locate the first rotor element and the second rotor element relative to the chassis; a motor mounted to the chassis; and a drive assembly arranged on the chassis and configured to transfer torque output by the motor into the circular outer drive surface to rotate the rear axle via the set of hub adapter brackets.

An assembly for minimizing the disengagement of a chain from a chain ring is disclosed. The assembly includes an inboard leg and an outboard leg. Rotation of the outboard leg relative to the inboard leg locks the inboard leg in place relative to the outboard leg. Relative rotation locks the assembly onto a shaft. The assembly may include an outboard leg that snaps into place on the inboard leg and is capable of rotating between two extreme positions.

An assembly for minimizing the disengagement of a chain from a chain ring is disclosed. The assembly includes an inboard leg and an outboard leg. Rotation of the outboard leg relative to the inboard leg locks the inboard leg in place relative to the outboard leg. Relative rotation locks the assembly onto a shaft. The assembly may include an outboard leg that snaps into place on the inboard leg and is capable of rotating between two extreme positions.

The teachings provided herein are generally directed to compact vehicle drive mechanisms that can be used in the design of a foldable, carry-on vehicle. The compact drive mechanisms presented herein, for example, have contributed to the advent of the compact, carry-on bicycles set-forth in the teachings which include drive-and-steering units and drive-and-chassis units.

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.

Invention relates to the type of two wheel velocipede where the propulsion to the rear wheel is achieved by the use of riders legs/feet and propulsion to the front wheel is achieved by the use of riders arms and upper body on cranks that travel in circular motion using a single chain as a means to transfer force to the front wheel.

An innovative step is the chest and upper body support pad which enables the rider to relieve strain of the back muscles and provide a surface against which to pull the handlebars