with the american classic there isnt an axle as such, it has more like spacers. that is why it is light and thats why it reccomends using a quick release, because the hub couldnt take bolts. also stan shaw had an american classic and the disc mounts bowed in on it so it bent his rotor round the mount (wierd i know). these reasons are why people use hubs like the pro2 because it is a pretty light weight hub,which is good quality and is mega reliable with great performance. steve