... fitness level is but one explanation of HR differences. However, what you seem to have described (specially when you mention "hanging out" HR) most like is caused by genetic differences.

Hearts are a bit like feet. Some feet are bigger than others. Hearts can be the same. Some have hearts which are larger than others. So, HR can vary because of heart size alone.

As for spikes and troughs (i.e., HR drift) and HR drops after activity may be more directly related to fitness levels. Or, it could be their particular racing/training technique... some individuals will naturally increase pace while others will decrease pace as they progress into the activity.

FWIW Joe Moya

In spite of Hardcastle & McCormick's running bet, heart rate from one person to the next means almost nothing. I remember reading somewhere that while Indurain's resting HR is in the low 30s, Raul Alcala's was in the 60s. For two Tour contenders to be that greatly different is surprising. No doubt those same differences can be seen while racing too.

I have a really low resting HR myself. I wore a Holter Monitor one night while sleeping, and my heart rate went as low as 34 BPM. And I get dropped by dudes on Huffys on a regular basis. :)

All true but your chronotropic response is an important indicator of fitness. Your Hr gets up faster and drops faster so id say youre fitter.