Kurt Kinetic Small Wheel Adapter. The small wheel adapter is required to use the Kinetic trainer on bikes that have tires with outside diameters (O.D.) of 22” or less. The SWA raises the resistance unit of any one of our trainers up three inches. By doing this, the trainer will now fit tires with as small as a 16” O.D., including most BMX, kids, and recumbent wheel sizes.