Originally Posted by
tomato coupe
Here you go ... 10 rides on the same route, logged on a Garmin Edge 520 without a wheel sensor. The starting point probably varied by about 20 feet, and the finishing point by about 5 feet. If you dig into the files, you can extract a couple more digits for the distance, and compute some basic statistics:
Mean distance = 29.794 ± 0.017 mi. (Actually computed from 20 rides)
So, the relative uncertainty is at the 0.06% level.
Not to imply anything about TC's data, but it reminds me that having suggested it I'm obligated to say something about methodology.
- Make sure you're not selecting among the different rides. Use all of them that are applicable.
- It's good to select from a given time frame, and not from a given distance, type of ride etc. Same reason as above, and to eliminate variables.
- If you have a "snap to road" option in your software, turn it off for the checks. Snap to road will basically report the map distance, not the bike's true distance.