I just ordered a Vista HCx online. I should get it just in time for my trip to Europe. I looked at the handle bar mounts and it's not clear fro what I have seen which bar mount I need to buy (I run the standard 24.5mm / 1" bars). From the garmin site it's the part number 010-10496-00 (Large Diameter Rail Mount Adapter). Do I need anything else (does it mount on the standard battery door or is there another door for it?)?