Looked at my HR data from Saturday. Looks like I rode at Z4 sub threshold level or higher for 62% of the time I was in the saddle. If Hermes, AJet & other students of analytics are checking in, perhaps they can provide a bit of insight as to whether I, in fact, "cooked" myself going out too hard for conditions and resultant heart rate(s). Just trying to understand cause(s) to prevent a recurrence in the future.