On the Tandem and me and my Co-Rider had the same Heart monitor. He is 45lbs heavier than me and I weigh 145lbs. So he is approximately 25% heavier than me and we set our monitors up to our own weight. He was showing 25 to 30% more calories burned than me so By ratio I reckon the monitors were about right. As to whether they were giving accurate readings- I would not like to say.
All I can state is that on the long rides we used to do- He was eating about twice the amount of Fuel than me and neither of us was gaining weight---or losing it from our norm.
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How long was I in the army? Five foot seven.
Spike Milligan