If you look very hard where the brass bit connects to the speedo, you will see a very tiny slot head grub screw....... It can be a pig to get undone and then you drop it and lose it............I think I have seen some with a small R-Clip instead (or is that what I did on mine.....?) Much easier to get at if you have the fairing off.....
Here is a photo of the back of the speedo............you can see the tiny screw in place (bottom right)....... I was right.........mine now has an R-Clip.........
I opted for the R-Clip for no other reason than I can't be a*sed to take the fairing off, just to get at the screw....much easier with a clip. The problem with the trip cable is that the knob seizes in the dash mount.........rust etc.......There is no outer to the cable as such, only a loose plastic sleeve.