To the happy, you-gotta-move-with-it music, Karen Lauer pedals fiercely on her stationary bike at the front of the room, urging participants in her spin class to do the same. As the song trails off, ...

The best exercise bikes serve up incredible workouts without taking up as much room as a treadmill or rowing machine. Their low-impact nature means they're easier on the knees too, and come in ...