MrJamie
Oaf on a Bike
GPS varies depending on the sample rate the app uses and the way it interprets data and depending on your ride too.Questions: Which is more accurate Google Maps or Strava/iphone GPS? Can I claim a sub 5hr 100 mile?
If you ride in a dead straight line for 100 miles, you only really need the start and end point, any points on the way that arent absolutely precise are adding small amounts of error data, which even at 1 or 2% can add up to a few miles on a 100 mile ride. On the other hand if youre doing a downhill slalom type ride the gps probably wont sample often enough to follow your route exactly and will essentially cut corners reducing your overall distance. For the guys writing the gps apps its a fine balance between oversampling adding in extra distance from cumulative tiny errors and under sampling cutting corners. On these apps the sample rate on cycling tends to be considerably higher than running which in turn will be higher than walking, as in to not add too much extra distance to each, but its far from perfect without using a bike wheel measurey thing.