Originally Posted by
Tourist in MSN
Occasionally a GPS will add a point in a track that has an erratic (false) location, but if that occurred your distance should have been off too. If you plotted up the data, did you see an odd peak or valley show up in the plot where there was no such land feature?
Every company that makes trackers has some method to deal with dirty GPS data. I think on average they are ok but small corrections on a long ride can add up quickly.
Here is an Strava's
explanation
I'm no KOM chaser but I do like to compare some of my own times on some sements. There are rides where Strava is missing a segment I did on a ride. There was some obvious GPS issues on my Elemnt and Strava didn't have a good enough stream to see I did that segment. The map shows me there but I guess just not accurate enough.