Originally Posted by hhnngg1

Even more important, is how much time do you actually spend in a training-type heart rate zone (zone 3/4+).

You can sit on your bike for hours on end, and barely get a workout. I stopped doing the local weekend 4 hr group ride since between the stops, regroups, no-drops, average speed became close to 11mph. I can almost RUN that fast. (Ok, not for 4 hours, though.)