I've been putting in some good miles this summer and losing a bit a weight...and getting faster on the bike. I'm 44, 185lbs. My previous highest recorded heart rate was 182 but yesterday I hit 189 in a sprint in a friendly crit. Pretty well max effort. Does it make sense that I can reach this heart rate or it there likely something wrong with my heart rate monitor. I time trial at about 172bpm for 25 minutes. Would this be 85%? Would it make sense to use that as 85% and adjust my heart rate zones accordingly? Or is it reasonable to be able to ride at say +90% for 25 minutes? A year ago max hit was 170, then 174, then 178, then 182 now 189. This is all good, right? Any comments greatly appreciated. Thanks.