This is my idea of a great solution for the C14's lack of a helmet lock. What you see pictured below is call a "Barender". They replace the stock weighted bar ends and provide a place to put your helmet when there isn't room in the bags. They're stainless steel and of very high quality. A barrel lock is used to secure them. They don't come with the spacer, but that does not pose a problem to those of us who own a lathe, have a friend with a lathe or are willing to pay a machinist to make the spacer. You can make your own as I did or have one/them made for you. For those of you who are interested, the URL is:
http://www.barender.com/I have one for each bar end and find them the be the best solution for the lack of a C-14 helmet lock that I have ever seen. Their weight is about the same as that of the stock bar end weights and provide equal vibration dampening.