Originally Posted by
MMACH 5
The GPS also does not account for extra distance when traveling over hills. When you have at least four satellites available, most GPS units will give you the altitude, but it does not calculate that into your speed or distance.
This is why even GPS units that are designed for cycling, incorporate a wheel magnet/sensor to measure speed and distance.
In this cross-section of hilly vs. flat rides, the GPS only knows how far you went and how long it took. It doesn't take into account the hills in between.
I think that your cycling computer is actually correct and it is the GPS that is off by 2%.
Dang! You made digital images to answer the question, then uploaded them to your ISP's free storage area, got the URL and linked them here. The scary part is that I have actually done that before too. And I thought I was the only one who got that bored.