As magpie referred to, so is heart rate measurement.
My first reaction was to ask you how knowing “precisely” where you are at any moment helps you become faster. However, I then realized that I know just as “precisely” where I am at any moment simply by monitoring my body’s signals and occasionally timing workouts and/or races.
And I see going by feel/time as a method that is based more on real world variables, as do a number of high level coaches and athletes.
And I feel a body’s signals are the best tools for this job, again as do a number of high level coaches and athletes. Notice a pattern here? If so, it’s because I base my beliefs heavily upon what those who have proven to know the most about the sport believe.
Are you trying to prove my point for me? You just showed how science can be used in cycling that is an unrealistic application for running as well as some of the variables in cycling that are much different, if they exist at all, in running. You also forgot to mention many of the training differences between running and cycling, such as the fact that one can recover faster in cycling because cyclists don’t have to worry about the high impact factors of the sport.
FWIW, I think it’s fair that you know you’re having this discussion with someone who has tried HRMs in the past. It’s not like I’m coming into this discussion not knowing both sides of the equation. I found the HRM to be useless and, at times, limiting.