Originally Posted by
Iride01
5% is still a difference from the real number.
Most of my argument concerns Calories, which is a dietary thing. When we get in conversations it is hard to know whether someone is talking about the work needed to move a bike and rider a certain distance or whether they are talking about how much energy their body burned while doing that particular amount of work.
If you want to believe that it's such a small number and doesn't matter. I'm actually in agreement with you. It's not big enough to matter. And that goes for either power meter or Calories derived from a cyclometer with HR.
Power meters are more accurate. There is less to argue about with their data for any one particular ride. But they aren't perfect.
So most of my argument falls apart because you and I aren't talking about the same thing or application of how it's used.
The variance between bike computers and methods used with HRM for caloric measurements are a LOT more than 5% to the point where they are largely useless.
I looked at Garmin, Garmin with HRM, Garmin with PM, and then between the same for Wahoo and for an iPhone App called Cyclemeter. The variance was about 100% - literally twice as much between methods. And around 40% with HRM to PM on a given brand. Repeatability was not good either because heart rate is influenced by a lot more than just exercise. However, the correlation is super tight between a PM because it’s a direct measurement of the effort or energy put into the cranks.
5% is a pretty good tolerance for most things engineering and I think that applies here. I agree, that is small. But the HRM methods to measure calories are not much better than a guess.
I had many of the same arguments until I finally bought a PM and tested it. I’ve been riding with them now for about 5 years and it’s been consistent. Go verify this yourself. You’ll get the same results.
J.