Join Date: Apr 2002
Location: Dandridge (Near Knoxville), TN, USA
Re: Why the difference?
That is an easy one. GPS mileage is very accurate, when basically riding straight line. However, when riding a lot of twisty roads it will be short.
The reason is that GPS calculates speed every fraction of a second so that will be accurate no matter the path, but distance is done on a much longer sample rate. OK for straight line, but on curves the distance between sample points will mean that you have gone around the curve some distance, and the sample points are connected by straight lines. So, the calculated distance is the sum of the straight line segments around the curve, while the actual distance traveled around the curve is longer.
Also contributing is up and down hills. GPS distance will be shorter as the distance calculation in most civilian GPS units does not calculate altitude change well, if at all.
GPS is very accurate for speed, not as good for distance.
I don't want to achieve immortality through my work...I want to achieve it through not dying.
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.