Exclusive Rim Drive Action Trainer with magnetic resistance system drives wheel without contacting the tire * Ideal for use with knobby MTB tires and for road racers wanting to avoid tire wear * 7 resistance levels controlled by smooth and quiet magnetic system; ultra-strong double-wall steel frame * Compatible bike wheel sizes from 26 to 27-inches and 700c; can handle up to 264.55 pounds (bike and rider) * 1-year warranty for the mag unit; 5-year warranty for the frame