I have been using mapmyride plus a Sigma 2209. I use Sigma for cadence and HR. I notice that the total time of ride is significantly different between mapmyride and Sigma. For 25 miles there is consistently 60 to 90 sec difference. I am using a Iphone 5 mapmyride app. I think difference is due to pause time. The Sigma must pause faster when I stop for stop lights or rest faster than the mapmyride app. Would cyclemeter be more accurate and can I use cyclemeter with windows 8? They only talk about using with IPAD.
I use Cyclemeter and have the same problem. The iPhone GPS seems to "drift" sometimes when you're actually stopped. The next time you stop take a look at your phone and see if the app is registering a really low speed, like 0.5-1.5 m.p.h.