Can I just ask how people are measuring their runs? The reason I want to know is that I've just noticed a massive discrepancy in the length of my run depending on how I measure it. I had measured it using the measuring tool with Google earth, and was happy with that; but I've just been out on my bike and my bike speedometer says I've completed 1.5miles 160metres before google earth says I have. This could be a difference of maybe 30 to 40 seconds over the 1.5mile best effort back!! (i've checked my bike speedometer's calibration, which is set to 2099 for the 26*2.0 measurement on the tyre. But i suspect this may still be wrong). Does anyone know how accurate google earth is and/or of a more accurate way to calibrate a bike speedometer???? Ps. i've now tried measuring 2 different 400metre running tracks using google earth and i was only 2m and 1.5m out with each - which is making me think that google earth is pretty accurate.