Known as exercise bikes, spin bikes are now available with LCD screens to keep track of your goals. They usually use magnetic resistance or frictional resistance. Because spin bikes have heavier flywheels, they require more effort and muscle activation. The transition between resistance levels is very smooth and very quiet, so you can concentrate more. Adjustable seats, handlebars and pedals allow you to adjust the position for comfortable training. The spin comes in a foldable design that saves space and is easy to store. Spin bikes are available in different colors and different sizes.