So I've been doing simple walking for about half and a half now, and have never had any problems with the activity app. I started cycling yesterday, and it was only logged 20 minutes with a 49 minute ride. The post-workout screen said it couldn't provide a heart rate chart. I saw this up here, and most posts said they were going to carry the band tighter, restart the phone and / or watch, and clean the heart rate sensor on the back of the watch and it should fix it. I did all these things before I went on a walk today. I just got back, and the same thing happened again. 4 minutes with a 27 minute ride, but it had a heart rate chart. So I'm not quite sure what to do. I used this watch before, about 2 years ago for bike rides, and it seemed okay then. Anyone have any suggestions?