Abstract: A cordless treadmill including a frame, a belt system, and a drop-in cartridge is disclosed. The cartridge includes a plurality of staggered rollers configured to provide tactile feedback to the user. The frame is adapted to receive the belt system and the cartridge as they are lowered into the frame, and the frame is adapted to place the belt of the belt system into tension as the belt system is lowered into the frame. An integrated flywheel generator system provides smooth operation of the treadmill and generates electricity to power additional systems.