Originally Posted by
EnsitMike
No, your monitor seems VERY far off. 120's is not even close to accurate for 24mph unless it was downhill. Even if you're a fairly strong rider, your heart should at least rev up to 140's.
Originally Posted by
EnsitMike
Yes, that is a bad reading. Heavy breathing is pushing in or around the 160-170BPM range, possibly into 180. What HR monitor did you buy?
You can't say that. HR varies significantly by individual. Also the power someone can put out at their LTHR will vary dramatically from individual to individual with training.
The fact that the OP has a resting HR in the 40's would indicate he's pretty fit. It could be that his LTHR is 130, which would be rather low, but not off the charts.
For one individual with a low LTHR and very good power at threshold, 24mph, particularly for a short period (the OP didn't say he was averaging 24mph) they might see a HR of 125.
For another individual with a high LTHR, and poor power, 24mph might be 195bpm.
And for the same individual, 24mph might be 140bpm one day, and 180bpm another, depending wind, grade, duration,hydration fatigue, etc (which is the reason we use power meters.)
The only way for the OP to sort any of this out is to do a field test. Assuming he's otherwise in good shape, and been riding a fair amount he can do a field test and determine his LTHR, and set zones from there.