My kids on motorcycles are my worst fears, it's just too bloody dangerous for them. So, I've banned them from riding. They are 26, 29 & 36 years old, I'm not sure how effective the ban will be.
I have offered my daughter's boy friend the Mighty CB1300 for a ride anytime though. 
Not sure how much I agree with this; surely what you are saying is that you are happy to control you kids, despite their ages, simply because of the slight risks involved in upsetting you, however you are happy to give a ride to some-one not in your family on a 1300cc motorbike. Surely, if your kids want to ride, at their age there is nothing that you can do about, and neither should you be able to do anything about it. It is their choice. I would have thought that the better way to approach your fears in this would be to make sure that they are properly taught how to ride, and practice effectively by going out with them on rides.
Please understand that I am not complaining about this, just getting confused with the reasoning behind the situation, after all if riding is "too bloody dangerous" why do
you do it?