Use these axle nuts to put a city or track bike in the Tacx trainer. They are only suitable for the Tacx classic trainers. Separate adapter sets are available for direct drive trainers. The available axle nuts are: T1415 Axle nuts M10x1, T1416 Axle nuts 3/8 Shimano Nexus. They are only suitable for the Tacx wheel-on trainers.