Maurizio, with an international driving license you can ride in Hong, Kong and Taiwan, but not mainland China.

French bikers are wrong, an international driving license is not enough, you need a Chinese motorcycle license to ride in China legally. It sucks, but that is the law. However what would happen if you rode without a Chinese driving license? The worst that could happen is that they impound your bike, fine you and put you in a detention center for 7 days. However there is almost 0.1% chance of that happening outside of a very big city like Shanghai. You could bring your Italian Euro license and translate it into Chinese, and bring an International license, as they would be better than nothing and might help.

China is all about money, if you have that then you can pay any 'fine' you might get...usually.