I was trying to fit my 305 quick release mount on my bike and the only place I have is the stem (I have profile design aero bars). The bike mount available is for handle bars. After looking around online I was able to find a good solution. I thought I would post it here just in case someone else needed it. I tried it and it fits well enough and tight enough. I am happy. http://jvanis.blogspot.com/2009/08/installing-garmin-forerunner-305...
I ran across the same site when trying to figure out how to mount mine on the stem. My stem did not have as steep of an angle as the one in the picture so I ended up shaping a piece of high density foam to use as a wedge to get the angle right.