I just got a Garmin for the bike, and after charging the battery and turning it on for the first time, it wants to know the position format I want to use. It defaults to degrees-minutes-seconds, which makes sense, but there's also a choice called "US National Grid." And of course there's absolutely no discussion of it in either the quick start guide, nor in the actual manual.
Can anyone offer any hints about this particular setting?
It doesn't matter unless you intend to enter or read out numerical coordinates. Most often you'll see coordinated given as degrees:minutes:second with whole degrees and minutes, and seconds with decimal places. The next most common is degrees:minutes with whole degrees and minutes decimal places. Less common is simply degrees decimal places. It's straightforward to convert. http://en.wikipedia.org/wiki/Geograp...ate_conversion
Typical Garmin documentation; leaves you in the cold. You could call them or email them and get an answer that might be right or wrong. But the person above who said it doesn't matter was right on if you are only referring to using the 500's routing function to keep from getting lost. Heres' why:
The only time the reference grid matters is if the device is trying to match coordinates with a chart or map. In that case for the matching to make any sense both have to use the same grid reference. Since the chart/map was already constructed using a particular grid reference that means the GPS must use the same.
Just be sure if you are going to construct a route using some application like Mapmyride you match reference systems.
It sounds complicated but a wee bit of practice and you'll have it figured out.