Traditional exercise bikes use brake pads or belts to add resistance to the workout. Often times the result is noise, jerky pedal motion and the need for routine maintenance.
Magnetic resistance provides smooth quiet pedal motion. The tension is created by a placing a magnet close to an aluminum flywheel. The closer the magnet is to the flywheel, the greater the pedal resistance will be. The magnet never touches the surface of the fly wheel!
When shopping for an exercise bike, don't assume that a bike has magnetic resistance; most bikes don't. If it's not mentioned in the description, then it doesn't have it.
"I am immensely pleased with both the build quality and the resistance. This will provide good solid exercise when couch-bound. Great for those of us who don't like to go out in the cold and/or have small apartments."