Kinetic's Road Machine Trainer, automatic resistance that adjusts as you change speeds so you get a true outdoor simulation. With a 6.25 lb. flywheel and a sealed fluid chamber pushing back, natural resistance feel and low operating temperature for consistency. To store or transport the unit, fold up the legs and put it away. 2 1/8-inch roller - tire wear is reduced significantly. Stationary bike bicycle trainer. Great for tight schedules and winter to get rides in. Regular and 142 x 12mm thru-axel fine thread included.