A flywheel is both a metaphor and real-life tool we use in cars, trains, power plants, engines and more. It’s a simple wheel on an axle that stores energy as it spins. Once it’s spinning, it takes ...

In the hierarchy of things to dread at the gym, “stationary bike” ranks somewhere between “treadmill” and “that sweaty ogre who grunts while bench-pressing the equivalent of a Volkswagen Beetle.” Sure ...