I have just the opposite question... will the STT fender fit on an XB12s? Seems to me the upper fender needs to bolt into something underneath the light but my xb12s doesn't have any mounts. I'd like to add the off road fender as I live down a gravel road and was planning on putting some more aggresive tires... (and I like the look).IMG_20170605_132355 (002).jpg
The front STT fender center bolt goes right into the adjustment bolt/hole under the words "USA" on the light housing in your picture. The other two holes to secure it are on the lower triple, it appears you will need to drill and tap the opposite side from the brake hose to mount it.