Heart rate not correct during an activity with chest strap on.

Hi Richard - 

Start out reviewing this article - Garmin Watch Optical Heart Rate Accuracy Tips

1. Are you starting the Indoor Cycling activity?
2. During the activity, how many of the green lights on the back are flashing
3. Are you gripping handlebars or doing anything that would cause tension in your wrist?

HI Tracy

1. I wasn't as I was recording on zwift which then shared with Garmin and Strava, the issue was that the heart rate was not the same on my watch as my chest strap. I am now starting an activity and have paired the chest strap to my watch so that it uses that data for my intensity minutes for garmin connect, then discarding the activity as the other stats are recorded via zwift. Is there a way to not have to do this and still get an accurate heart rate from  my watch during a zwift ride? are all the other transmissions effecting the heart rate?

2. Yes all lights still flashing, works perfectly when riding outdoors.

3. Yes sometimes, have tried all sorts of watch positions and both arms and holding the  bars loosely but no change.

Each activity type has its own algorithm for heart rate monitoring. If you watch the green light patterns on the back of the watch you will see the number of green lights flashing increases when an activity has been started.  I would expect there to be a difference between the watch and the HRM simply because of device location and and function, but only a couple beats a minute or so. 

That being said, an activity has to be used. If you want the watch to display the most accurate heart rate you will need the HRM paired to the watch. You could opt to return to your original configuration but start an activity knowing you will discard it at the end, I would expect a slight difference between HRM and Wrist Heart Rate if that route is chosen.