ShakeIt - rumble effects in ACC with Buttkicker Gamer Pro. Effects last longer than on curb?

I've just received my Buttkicker Gamer Pro today, to be used solely with ACC on PC, and find the included Hapticonnect software quite disappointing. So I then installed Simhub, after hearing it offers a superior experience. However, I'm really struggling to set it up. Basically, I mainly want effects when I hit curbs, rumble strips, or grass. I seem to have got this going in the Road Rumble area, but it has one major issue - I hit the curb/strip, it activates, then I get back onto the road, and the effect lasts for another half second or so. How do I set it up so that the effect is only triggered while I'm on the rough surface? I've tried adjusting the various settings on the fly, with no luck.