A magnetic clutch transitions a drivetrain or flywheel between a freewheel or unlocked mode or configuration and a locked or fixed gear mode or configuration. The magnetic clutch includes a rotor rotationally fixed to the pedals of the drivetrain. An armature is connected to the flywheel. A field coil generates a magnetic field which causes the armature to move to the flywheel. Friction between the armature and the rotor rotationally fixes the flywheel to the rotor.

A left leg unit includes a vertical piece; a horizontal piece; a vertical guide groove; a horizontal guide groove; an outer coupling bar to which the vertical piece and the horizontal piece are rotatably coupled, thereby coupling the vertical piece and the horizontal piece to each other; and a pedal that is rotatably coupled to the outer coupling bar. The vertical guide groove and the horizontal guide groove are extended in such a way that they intersect with each other. A rotation axis of the pedal is disposed away from a rotation axis of the vertical piece and a rotation axis of the horizontal piece and is disposed away from a midpoint of a line that connects the rotation axis of the vertical piece and the rotation axis of the horizontal piece, whereby the rotation axis of the pedal moves along an elliptical trajectory.

An epicyclic pedalling apparatus comprising: a first epicyclic arm comprising a first pedal crank arm connection for coupling a first pedal crank arm to the first epicyclic arm to enable pedalling of said first pedal crank arm about a first spindle axis; and a second epicyclic arm comprising a second pedal crank arm connection for coupling a second pedal crank arm to the second epicyclic arm to enable pedalling of said second pedal crank arm about a second spindle axis; wherein the apparatus is arranged to enable: (i) the first epicyclic arm to rotate to move the first spindle axis, and (ii) the second epicyclic arm to rotate to move the second spindle axis.

An exercise machine has a crankshaft having a crankshaft mounting surface, a landing surface, and a crankshaft bore, a crank arm having a threaded crank arm bore and a crank arm mounting surface that is frictionally engaged with the crankshaft mounting surface, and a fastener that axially extends through the threaded crank arm bore and into engagement with the crankshaft bore to fasten the crank arm to the crankshaft. The threaded crank arm bore is configured for threaded engagement by a removal tool such that removal of the fastener and insertion and rotation of the removal tool in the threaded crank arm bore causes the removal tool to disengage the crank arm mounting surface from the crankshaft mounting surface and thus facilitates removal of the crank arm from the crankshaft. Methods of disassembling an exercise machine having a crank arm are also provided.