I can't really answer many of your questions, except.... You've seen my TT bike, which is my first TT bike as of September this year. I built that bike, and got a professional fit from one of the profiled fitters here on ST:

https://www.slowtwitch.com/...ern_Plains_7066.html

My sustainable power before and after the fit on both bikes, in both aero and upright positions is indistinguishable. 217 watts at 92 rpm. Leading into the change to the TT bike, I consciously did 2x20 intervals every week in the different riding positions. I did 2x20 upright on the road bike. Then I did 2x20 upright on the TT bike before I got the fit. Then 2x20 on the TT upright after the fit. Then 2x20 on the TT upright for the first 20, and aero for the second 20. Then 2x20 in the TT in aero for both. Every interval was within the range of 212 - 217 watts. The only oddball was the 2x20 on the TT upright before I got fit. My seat was very low (5cm), and my cadence was elevated by about 12rpm. After my seat was raised the cadence returned to my normal 88-92 ish range.

I'm very comfortable in the TT position. The only caveat to that is my neck because my position is pretty low. But, all of the contact points and the pedal box are totally comfortable. If I didn't have to look up, I can stay there "all day." But, I only race OD. So, I can manage the neck for an hour.

ETA: My 2x20 HR is 159 in all cases. Again, no change based on bike or position.

So many threads on this:

* https://forum.slowtwitch.com/...%20position#p6392228

*https://forum.slowtwitch.com/...%20position#p6288466

* https://forum.slowtwitch.com/...=tt%20power#p6754481

Thanks for the links...those were very helpful. However, not much discussion as to the training side of my question. How does everyone train? Should I be doing intervals in TT or upright?

I tend to do 20 min or longer intervals on the TT bike. Shorter ones on the road bike. For me it has gotten to the point where I find it easier to do the threshold type intervals on the TT bike. I think part is mental ("TT bike = TT mindset"). But also I just feel more comfortable in the TT position for the longer duration. And my position is fairly aggressive since I'm doing at most 40k TT not triathlon distances. Power is the same as on the road bike, unless it is a sustained climb.

You’re going to get mixed opinions. Some train in road positions and race in TT position with no issues. Others have to train in TT position to be efficient. I tend to do about 99% of my work in the TT position. It’s more comfortable and my power is higher. That’s probably bc I never ride my road bike anymore.

I’d say train in the TT position until your FTP gap is closed. Then do what works best for you.

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Team Zoot - Great Lakes

if you are positioned correctly there is no delta in power between road and tri.

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Dan Empfield
aka Slowman

Not that it needs it, but I am going to second that. I would not settle for any loss of sustainable power in aerobars. I think you should do all intervals of 3:00 or longer in your aerobars, and that is the approximate duration I am referring to as sustainable. I've seen too many riders achieve parity to accept anything else.

I only use my tt bike for intervals in the early season and ride road/mtb for all others (unless I have an early season ride and want to get more time in aero). As my big races approach, I move to where all of my rides are on the tt bike. Specificity.

Since I've raced Xterra for the last 2 years I had been doing most of my road riding on my road bike so most of my intervals have been on that bike.

When I rode my tri bike there was no difference in the interval power/effort. In fact I felt it was easier to modulate the power because I use my aerobars for leverage.