IMHO..The Fitbit trackers work best when you are running/walking, but for a truer elevation record, try using the GPS feature when biking. I live in a pretty flat area, on a sunny day, I can walk 10 miles and get maybe 1 or 2 flights (20 feet maybe). When the air pressure is falling (say, clearing up after a thunderstorm) I can see a elevation change of 15-20 flights on that same walk. The fitbit altimeter is accessed through a small pinhole just under the side with the 2 hard buttons on it, and almost at the very bottom..Maybe when you are cycling the bend of your wrist is blocking the hole and not allowing the device to sense the pressure changes. I do know the GPS recordings of elevation are spot on. Another thing to try is to use your phones GPS feature in conjunction with the Fitbit App. The App will track your movements and sync when you are finished. This saves battery life on the surge and gives a pretty accurate report. Emujo
