A spin bike is designed to hold up the rider's weight. These bikes are made of strong steel so that they can handle pressure put on them as a result of the rider's body position changing during a workout. A spin bike has a seat that's usually smaller than what you'll find on a regular bike. The fast cycling motion you experience on a spin bike occurs as a result of specially-designed wheels and the bike's durable construction. A spin bike has one wheel that's connected to a weighted flywheel, which has pedals attached to it. http://www.yunpaosports.com/spin-bike/