Stationary exercise bicycles have many different types of resistance systems, including tensioned belts, air and magnets. Manufacturers use magnets on the flywheel of the bike to provide consistent tension during the pedal stroke that closely simulates riding an actual bicycle. Bikes with an electromagnetic resistance system are easier to use, and can therefore provide a better workout, than those with manually adjustable magnetic brakes.
Changing Resistance Levels
The biggest benefit electromagnetic brakes is that you can ratchet up the resistance quickly by pressing a button on the electronics console. If you have to manually adjust the magnets with a tension knob, the resistance will only change as fast as you can turn the knob, and the use of a manual system may cause you to break your exercising cadence.
Bikes with electromagnetic resistance offer a wider variety of exercise programs, which not only helps you train harder but will also keep you interested in exercising. The electronic console of the bike can vary the resistance level at specific time intervals as you ride, to simulate cycling outdoors. A bike with manually adjusted brakes only allows you to exercise at a specific resistance for a set distance, time or calories burned.
Though the way you move the brakes in relation to the flywheel is different, manual and electromagnetic brakes actually function the same way. Both types of brakes use eddy currents to control the speed of the flywheel. Walter Boyes explains in his “Instrumentation Reference Book” that as the magnets get close to the conductive material of the flywheel, electrons are spun in elliptical eddy currents in the opposite direction from that in which the wheel is spinning. The closer the magnets are to the flywheel, the more drag is created and the more resistance you feel pedaling.
A drawback of electromagnetic resistance is that it can significantly add to the cost of the bike. Lower quality bikes with manual resistance brakes typically cost less than $300, while an exercise bike with electromagnetic brakes could cost $600 or more.