Recording movement using GPS devices is always subject to error but when it comes to elevation data the difference in recorded values between two or more people on an identical ride can be rather dramatic. This difference can become even more extreme if the there is some rain in the air when some devices carry on unaffected whilst others hang up their barometers in disgust. Here I’ll present a small comparison of various recordings of elevation from Stage 16 of the 2015 Giro d’Italia which although not a typical ride for the most of us, was affected by fairly typical weather.