Originally Posted by
Andy Somnifac
They estimate the power, which has a direct correlation to calories burned. As the OP states, the question is: how accurate are the power numbers? I'd say they're certainly not exact, but at least in the ballpark, as long as they have correct elevation data.
nope they're not very accurate at all. i've had hills that were 30 watts off my real (measured with a powertap) wattage. BAsically just dont pay attention to it.