Exercise bikes are made with a variety of mechanisms to create resistance. Two examples include, magnetic and fan-based (think spin class).
The folding models use magnetic resistance exclusively. This is good news for someone considering an investment in a folding exercise bike. Magnetic resistance creates little wear and tear on the bike's parts, meaning a longer life and fewer repairs.
Other pluses of the magnetic resistance design include a quieter, smoother workout and the ease of adjusting resistance with the touch of a button.