I am glad that I ran into this post this morning. I find that my heart rate normally averages at 85% (131) of my MHR.whether it is 1or 2 1/2 Hr ride. I generally feel fine after these rides. I am hoping to do a century at end of the summer for my 66 birthday. My question is should I build up my endurance at my present effort and HR or should I concentrate on riding easier at a lower HR. The harder pace seems more comfortable to me. Thanks for any insight that can be provided. FYI Never had any heart issues RHR is in the mid 50s.