Originally Posted by chasm54

Sorry, you're not being obtuse, I am. I'm thinking of the pace I would run 5k on a training run, not race pace. Same for 10k. Difficult to describe the parallels between running and cycling, as I've just demonstrated.

Essentially a "tempo" hour is HR zone 3, the sort of pace that will leave you tested but not exhausted after an hour. And the 2x20 minute intervals should each leave you feeling that you could have gone harder, but not much...

Does that help?

EDIT: It occurs to me that you ex-runners might find some useful expertise in the triathlon forum. Those guys/gals will be better able to talk about the running/cycling transition than I am.