I removed the nut that holds the upper handlebar in place and machined a nifty little stub fom a piece of 303 stainless to go back in its place. 10x1mm are the threads on that nut and curiously enough that is not a common metric fastener but I did have a tap. After screwing it on in place of the nut I wished I had made it longer but I can always make another to go on the other side.