So I order a nautilus from Nippy Norman (excellent service btw) and made a nice stiff bracket. The fitting came with a simple bolt and nut, which I replaced with a nyloc and added washers. Seems that was a mistake, coz the damn thing fell off after about 200 miles and destroyed itself on the road 
The bolt is clearly supposed to go in the open slot on the horn (rather than the hole, which is too small), but it seems that the vibration would soon loosen the bolt and allow it to fall off.
How did you fit yours?
(1150GSA btw)

The bolt is clearly supposed to go in the open slot on the horn (rather than the hole, which is too small), but it seems that the vibration would soon loosen the bolt and allow it to fall off.
How did you fit yours?
(1150GSA btw)