Mtn biking4:40:00 [3] 60.0 mi (12.9 mph) ahr:120 max:140 shoes: Trek MTB Bike 34lbs
With 20 lbs of gear. About 30% gravel. Avg ~13MPH Avg HR after 1 Hr was 130 after 2 hrs it was 120 and stayed there. Exceedingly harder to keep HR up on a bike than running Why??