I want to dial in my cockpit and trying to find the best mounting system for my iPhone (with water proof case), as well as my Garmin Edge 810.  In a perfect world, I could swap out the 810 and easily pop on my backup GPS (eTrex30) if necessary.  I would love to hear about highly recommended mounts out there? Also, I never had issues with a GPS falling off the stock 810 mounting system the first time I raced the TD but I think I have heard people tying them down better with a lanyard.  How do you do this?  Thanks for the help, much appreciated.