Why Does My Watch Say the Race Was Longer Than the Official Distance?
The Extra Hundred Metres Nobody Ordered Most of the gap comes from running wide of the tangents, not from the watch, so a better receiver only trims a little. If you race in a dense city centre, multi-band reception is the one purchase that helps, and everyone else should start the watch at the line and take corners deliberately. You cross the line, stop the watch, and the screen reads 10.18 kilometres. The race was a 10K, the course was certified, and your watch has just quietly told you that everyone else got it wrong. This happens to almost every runner who wears a GPS watch, and the reaction is usually suspicion. Either the organiser measured badly, or the expensive device on your wrist is not as accurate as the box implied. The truth is duller and more useful. Both numbers describe real distances, but they describe two different paths through the same streets. Once you understand which is which, the gap stops being irritating. It becomes a small piece of feedback about how e...