>Gears and Wears>GPS Accuracy of Nike+ Sportwatch
For the past two years I have been using a Nike+ Sportwatch. I have noticed that the Sportwatch calculates the distance ran considerably shorter than what is indicated on a mapping service. The watch calculated today's run at 8.76km. However, when I mapped out the run using mapmyrun (and Nike's route mapper) the run came out considerably longer at 9.2km. This has a huge impact on my pace (nearly 20 seconds per km). I use the Nike+ foodpod as well as the GPS (hoping together that the accuracy would be improved).
Do Garmin GPS watches have the same issue?
Trust Me, Im an Engineer
I use the sportband and find it is very accurate, it uses only the footpod, it is only a couple percent off of my running buddy's Garmin. From what I understand the nike sportwatch uses Tom Tom, where as the Garmin, well uses Garmin. The discrepancy found of the measuring might be a difference in satellite position and availability. Now, I use US Measurements, so your numbers indicate a .25 mile difference, which I have found is not unreasonable but definitely off. I have heard that Nike's Sportwatch does get not as good of satellite reception as the Garmin's so they do have an advantage.
Garmin has better satellites and as such has a much smaller margin of error on distance calculations. Footpods are only as accurate as calibrations.
Not all those who wander are lost - JRR Tolkien