Changes

The Stryd is so accurate outdoors, I couldn't understand why it was so bad on a treadmill. To my chagrin, I discovered that the main problem is my treadmill speed display is way wrong. Accurately calibrating a treadmill proves to be rather more complex than I'd have expected, as the treadmill will slow down when your foot is in contact with the belt, then speed up when you're in the air. For details on how to evaluate your treadmill have a read of [[Treadmill Calibration]]. However, this variation makes it tricky to know what the "true" speed should be. Obviously, the average speed of the belt is completely wrong, as the speed of the belt while your airborne has nothing to do with your running speed. During the time your foot is in contact with the belt, should you use the minimum speed, the average speed or the maximum speed? With my treadmill, the difference between minimum and maximum during contact is about 15%, and between average and minimum is about 9%. I've found Stryd seems to be quite close to the minimum speed rather than the average during contact. I calibrated my treadmill and then calibrated Stryd to the corrected treadmill speed, which is a lot of effort and tricky to get right. A much simpler solution is to use the [[North Pole Engineering Runn Treadmill Sensor]], which measures the treadmill speed with far less effort and greater accuracy.