I have a Garmin Zumo 665 which now outdated and can be purchased pretty reasonably. If you subscribe to XM/Sirius radio you can get weather and traffic alerts as well. I have mine hardwired into the bike but you can still pop it off when you are worried about security. Mine is six years old and has never given me any problems at all. That it is water resistant and shock resistant is a very positive feature. I also like that I can plan routes on my computer and download them into the GPS. I have downloaded multi-day trips of as long as two weeks with all the stops and it takes me directly to the front door of my motel at the end of each day.

In my opinion mine paid for itself in the first year. I recommend buying one with lifetime maps.

Good luck