I would say, don't rely on stride at all. It's very rare people walk or run with exact stride length. Stride will be different if you change the incline of the treadmill or if you change speed. Stride will change if you get tired etc. We are not robots :). Mind that there is no real way the watch will know the distance from the treadmill or any other non-GPS activity for which it's not calibrated. Moreover, I don't think such watch exists. Fitbit doesn't plan to introduce editing activities so if you want the accuracy of the treadmill the only thing you can do is this workaround:
- track exercise first
- then log exercise manually providing same data like time, duration, calories but update the distance to match the one you see on the treadmill.
- delete tracked exercise, leave one logged manually.
I'm not sure, however, if the step count is affected somehow by deleting the tracked exercise. I performed the workaround many times but never looks if steps have changed anyway. This problem is quite common for exercises like Indoor Rowing, Elliptical and some others. Unfortunately, as long as the exercise stays immutable after being recorded not much else can be done.
