I am a Vivosport owner and I finally found a way to get a reasonably accurate HR with indoor cycling ! It is a configuration problem. To remedy this , every time I cycle indoors, I follow this procedure:
1- I check the exact distance from my wrist bone to my elbow and multiple that by .237
2 - I locate the point at that calculated distance above my wrist bone (toward my elbow)
3 - Ensure that my Vivosport is located exactly at that point
4 - I perform a 4 minute breathing exercise with the Relax Timer and repeat until my Stress measures in the Low range
5 - I then remove the Vivosport from my arm and place it on a table
6 - Strap on my 3 year old Vivosmart HR in its place
7 - Exercise while accurately recording my Heart Rate.
Hope this helps!