Workout Summary: Spin 24 (1:11)

10 min wu and 5 min cd total 4 miles.
Did CT 0.5 mile flat TT course X 40 laps
Tried to hold power just over 200W ave. Kept HR below Ae cap of 139 for first 16 miles, then went with perceived exertion for final 4.
Total time 55:45 (20 miles)
Ave speed = 21.0 mph
Ave Power = 204 W
Ave RPM = 94
Zone Summary:
1 (70-115) = 11% (7')
2 (116-127) = 8% (5')
3 (128-135) = 18% (11')
4 (136-144) = 52% (33') (mostly held HR at 136-139)
5a (145-148) = 10% (6'20")
5b/c (149-170) = 1% (25")

*HR includes the cool down
I went into zone 5 for the final couple of miles. However, I didnt feel like I was working anywhere near my max, just a little heavy breathing.
I experimented a bit. Looking at holding 200 watts at various cadence. There is definately a breaking point. At cadence of 110 in easier gear, my watts would fall to around 160 and speed would increase. However, my HR would jump 5-10 beats. Then I shifted into more difficult gear, 54/12 and slowed cadence to 60 which increased my watts slightly to 210, maintained speed, and lowered my HR 8 beats to below my Ae cap. However, my legs began getting pretty tired.
At 85-88 rpm and mid gear, able to hold watts at 200-210 and maintain speed while holding HR at Ae cap.
I was watching 2001 TDF also, final TT stage. I mimicked Ulrichs cadence for 30 seconds or so. He was hitting 94-96 (God only knows what gear). Then with Armstrong. I had to shift into my 54/25 because he was cruising at a cadence of 116, and holding. Bottom line, is that I had to shift down to maintain this high turnover, and my HR shot up over zone 5 within 30 seconds.
I think the magic 90 cadence rule is pretty good for me. Up over 100 and my HR slips up quickly, even if I am in an easy gear. Too low cadence and bigger gear of course thrashes the legs (musc. endurance).

Diet:
breakfast: orange scone and med. coffee
Lunch: french dip sandwich and chips, water
Afternoon: small coffee
Dinner: 6 oz pork chop, pile of rice, about 2.5 cups. water.
1 beer before bed.