I installed the Madstad shield and brackets near the beginning of last season, and did not notice the rain problem you had. BUT, there are a lot of differences:
- I'm 5'9", 30" inseam, and got the 11" system. I look way over
the windshield. Not knocking your preferences, but I never like to look through a windshield. (Where I live, if it's really cold out -- when I might want all the wind protection I could get -- there's probably also snow and salt on the roads, so I park the bike in the garage for the winter.)
- I usually have my shield positioned about halfway in the upper groove, the groove that the knobs control. If it's very hot, I'll tilt the shield such that the top of it is lower in those grooves.
- I've never moved the shield out of its bottom-most position in the lower J groove, the groove that's controlled by bolts. That is, I've left that the way it came.
I remember last summer when I first encountered some significant rain. I took my left hand off the bars and moved it all around behind and over and under the shield for a few minutes, conducting my own science experiment on the interstate. What I found was the rain that was coming underneath the shield promptly curved up behind the shield, and then joined up with the rain that was flowing up over the top. That is, my results were that the air pattern was just as pictured in the flow diagram at Madstad's site ( http://www.madstad.com/
, and then click on the "Click Here" link in the red text).
But, as I say, there are all the differences in the way we have it set, our heights, preferences, and the 11" vs. the 13". So, all of this is FWIW and YMMV.