The kurt small wheel adaptor for new kurt turbo trainers a must for bmx recumbents and any bike with tires having an outside diameter of 22 or less the small wheel adapter raises the level of the resistance unit of any of the kinetic trainers by up to three inches by doing this the trainers fit tires with outside diameters as small as 16 by using this adapter kinetic trainers accommodate most bmx kids and recumbent bikes