The Nike+SportsWatch GPS on the other hand performed spectacularly well. My previous review discussed my initial impressions and runs with the watch.
Bottom line: Nike+SportsWatch was 99.05% accurate showing 26.45 miles for the 26.2 mile distance. Given I did not run all tangents I think this is remarkably accurate
The screen was very easy to see in the bright sunlight even with sunglasses on.
I watched for auto lap mile splits and kept an eye on elapsed time as I went by course mile markers. Very useful while I was still actually running... It was overstating my distance a bit as when I approached mile markers I saw it mark laps 20-30 yards before the actual mile. After the first few miles it seemed to stay consistent at 20-30 yards. As things went far south I was unable to do much about pace so I really didn't watch splits. As I got into Boston, the buildings likely interfered with signal losing a bit of accuracy. Nike told me at the expo that the foot sensor takes over when GPS signal is completely lost and not when it is weak as I might have expected.
See this screen shot of the last 600 yards or so of the course where the track is running to the north of the street over the buildings. Given my condition coming down the stretch maybe I was weaving that much! I reviewed the rest of the track and it was by and large right where it should be. As is known GPS signals are blocked by large buildings and as these are the largest buildings on the course by far, on narrow streets, so no surprise some variations. Further, I was running with GPS only, no foot pod which when GPS signal is lost is supposed to pick up the tracking.
|NIke+SportsWatch loses signal down the Boston Marathon stretch|
Unofficial update from Nike on the future of SportsWatch:
I heard "unofficially" from Nike folks at the pre race expo, who should know, that they are testing average pace for firmware release expected in July. They also told me the foot sensor picks up when GPS signal is completely lost not when it is weak. I asked what I should run Boston with GPS, GPS +sensor, or sensor alone and they told me GPS alone.. I could not get them to tell me what their GPS sampling rate scheme is.
I now have the Polar Wearlink+ Heart Rate strap and will be testing it when I can hobble a few miles later this week.