03 is compatible with 135 x 12mm (w/5 mm spacer included with every Tacx Direct Drive trainer), 142 x 12mm and 148 x 12mm
04 The thru axle adapter kit is for bikes with a 12 mm thru axle. The axle adapter is required to couple the rear stay with the thru axle mount on a Tacx NEO or FLUX Smart trainer.
