Originally Posted by coachboyd

Simple answer is that when you are rested (haven't been riding a lot) your heart rate will be a lot higher. As you ride more you will settle into your "normal" heart rate range.

I remember a couple years ago I took my winter break, which coincided with my honeymoon and three weeks completely off the bike. My first ride back I was sustaining low 180's for heart rate. Normally I can sustain about 170-172 when time trialing and my max is about 183. I think I hit 189 at one point on my first ride back. Over the course of the next few weeks my heart rate gradually went back to normal.