Originally Posted by Anders K
I've read somewhere that if you use a english threaded freewheel on an italian treaded hub you should not go back to italian threaded freewheel because the threads on the hub gets a little damage and there will be a risk of stripping the threads on the hub if you fit a italian threaded freewheel after the english treaded. Is this just in theory or just if you are a strong rider that apply much force to the threads?
I answered that recently in another thread. If you are a strong or heavy rider, it is inadvisable to mix English and Italian threading on hubs and freewheels. There is a 5 degree difference in the thread profile and it MAY cause failures.
It is generally safe to mix the Italian and English threads on hubs and freewheels for cyclists of medium strength and weight, however, once you mixed the threads, you should not switch back and forth.
The above rules of thumb are not just theory. I received a stripped English hub earlier this year, after the owner went back to English freewheel, because he couldn't find an Italian threaded replacement for the one he had worn out.