This is exactly the kind of use I'm interested in. Like the guy above me said try moving it more proximal on the forearm. From what dcrainmaker says w watch HR monitors it needs to be on a flatter section of the arm and tight to get a good read.
How does the HR data look post-ride? Can you use it for training analysis?
I know you can pair a chest strap, I had one of those and it was a pain, I was hoping the watch could provide sufficient data on its own.
It was tight, it wasn't moving around, even after stopping it took a while to get a reading. Maybe a different location higher up would work better, i'll try that next time.
In terms of analysis, its not too good, I leave it on the heart rate screen so I can check at any time whilst riding just by raising your wrist, assuming the watch can read it! It would be nice if you could also set heart rate zones in this view. I feel like the watch is setup for the average person rather than those who exert themselves a little more and its more focused on achieving daily goals rather than being in the right HR zone say. An athlete mode with more detailed settings and analysis would be useful I think.
In terms of analysis, you can view the heart rate history in table form, i.e. heart rate readings with a time stamp, seems to be about 6 per minute saved during a workout, its cumbersome to look through, it should be in a graph format really and against distance, altitude like on most existing apps, along with a map of your route.
If position on wrist (or improvements to detection) sorts out the missing HR numbers, and there is an export option to Strava with all data, I would be very happy with it.