Dunno why!
I had the bar mounts on the inner ends of both bars on both the original K12S and now on the K13S. Granted I have HeliBars (which don't utilise an under-bar steady arm) but that makes sod all difference.
You simply remove the plug in the inner end of the bar, stick in the taper-fit mount and do it up; simples and no need to touch the steady arm or the bar clamp bolts
I had to remove the bar end weight on my K12 and rod the plug out with a long thin thing as it wouldn't budge, but the one in the K13 almost fell out all by itself. Of course, the fitment with the HeliBars is totally different and a bit of a bodge as the bars are solid billet alloy
