Tuesday I went out and did a hard 10 mile ride in 95 degree weather. I hit my max heartrate of 180 four different times with a peak of 185. Yesterday I did the same exact ride with the same amount energy and reached my max once with a peak of about 181. Noticed on the second ride that I stayed around 160-170 range yet on the first one I hovered around 170-180 range more frequently. What can I tell from this? I typically ride 2-3 times a week but this was the first time I went hard back to back.