Ted,
I respectfully disagree with Stryd.
First, the top 10K split in the 2012 Olympic men’s triathlon event was 29:07. This is the same time as the 25th place of the straight 10K event from that same Olympics. There was only 90 seconds difference between the winning 10K time and the 10K spit from the top triathlete. Yes, they are different, but not that different.
Second, in your triathlon training you will be running clean: only off the bike in limited brick workouts. You can’t use a 10K Oly time to define clean running zones. Your threshold test must match the environment in which you will be training.
Certainly, as you incorporate race-specific brick workouts you’ll want to adjust the intensity within your clean run zones for the appropriate zone penetration for a race. But for the other 99% of your exercise when you are not racing, you’ll need zones based on “fresh” legs.
David
EDIT: I forgot to address your other question on bike position and FTP, but it also perfectly illustrates this issue. It’s the same premise: you should perform your FTP test in the same conditions in which you expect to perform most of your training. Indoors, outdoors, cold, hot, upright, aero… all these conditions will dramatically change your output. I go as far as having my personal athletes use a completely different indoor and outdoor set of zones.
It’s best to use an upright FTP test for early season and then switch to aero FTP test for the more specific phase of training. Fortunately, the nature of zones allows this to be easily absorbed in between those tests, as the zone range can usually accommodate the delta between upright and aero while still staying within the zone.