Yeah, sometimes it works ok, and sometimes it spikes right out of the gate. For a while I thought the key was to use the 'me' tile to get a hr rate lock for a few minutes before starting an activity, but sometimes that doesn't make any difference. It seems totally random as to whether its going to act up or not. Yesterday on the treadmill it started spiking to 120 after just a minute or less into a walk (should have been around 85 to 90). I could step off the treadmill, and it would quickly settle back to where it should be. Step back on the treadmill, and within a handful of steps it would be right back up to 120. Finally after about 10 minutes it settled down and behaved. I've had one or two rides on the stationary bike where it acted right, but that's about it. Same with the treadmill. Pretty discouraging, actually. I have a Garmin Fenix 3 HR on order, just awaiting stock. It'll allow me to use the optical hr for 24/7 use, and default to a chest strap for activities. If it works out, I may end up retiring the Band.