Simple is better
I attached my Garmin 60 CS to the handlebars with a simple bicycle bar mount, then hardwired the power lead and tied the lanyard around the bars for extra safety. I geocache, so it allows me to whip it off quickly to go for a hike, plus with the rough and tumble handhelds you never have to worry about waterproofing or durability. The bicycle mount lets me angle it to see the screen whether I'm standing or sitting, or to reduce glare depending on where the sun is. So far, it hasn't budged, even at high speeds on our washboard gravel road. Originally, I figured the mounting bracket would last a couple weeks and then I'd have to get a motorcycle specific setup, but here it is a few years later and I move it from bike to bike every day. I do wish I had a bigger screen sometimes though, so I don't have to take my eyes off the roadfor so long to focus on the map.
1974 BMW R90/6