Originally Posted by CdCf
Sure, in a flat area, with few and low hills, and no forests or tall buildings, the GPS is fairly accurate. Your close match was likely luck more than actual precision, though errors could average out over longer distances to some extent..
Not luck. I document and download every single ride I do. Very rarely is it off by even 1 percent. Now in all fairness, I do live in a rural, non-mountainous area but it is heavily forested. I guess if I rode around downtown NYC or along steep cliffs, it would be less accurate. The GPS is also great for average MPH, my unit always knows when I have stopped and will stop calculating a moving average speed and time moved.
But if I was really in need to be deadly accurate, I would get a cyclometer & calibrate it properly. But I find that being always under 1 percent is pretty darn good.
The only time I kick myself is the times I'll go walking for a geocache with my GPS while using it for bicycling. Or if I drive my car and forget to clear out the data. Then yes, it does mess up the data and I've got to reconstruct it from the GPS log taking out the distance and time walking or riding in the car.
Still a GPS is a great tool to have on a bike. And there's so many other things you can do with it besides bicycling.
I can't see them ever going back to Selective Availbity, too many public services and businesses now rely on GPS.