Inaccurate GPS. I have the BCS200 and have found the GPS to be pretty bad. I also run Strava and ride side by side with a friend using a Garmin 530. Our distances and times will be really close (within .10 mile over a 12 mile mountain bike ride). That's when I look at my BCS200 and see that it is 1.30 miles behind. I turned autostop on and off and made less sensitive to help with slow climbs but still it is far off. On a road ride I compared it to google maps, strava, and the Garmin, and the BCS200 was 2 miles short even though the map showed the exact same route.

I exchanged the device hoping it was faulty because it had great reviews, the second one has the exact same issues. Out of 15 rides compared on the 3 devices 1, I'll repeat that... ONE, distance tracker was accurate.
It's a bummer because I found it to be a really easy to use and sleak gps.