Scratching my head a little here. Don't have a power meter on my TT bike, but have one on my road bike, and the possible conclusions are interesting or maybe plain wrong
The TT in question was done on a "squared circuit", 2 laps of 6km each, sea level, sunny evening but around 10 C of temperature only, pretty slow wind and many trees around, so I'd guess the wind impact was quite minimal, certainly I didn't feel much.
For the 12km, I produced an average speed of 39km/h which was 2.3km/h improvement from my road bike testing of the same circuit last year. In TT, my HR was pretty close to max sustainable for that length of the interval, and therefore I'd guess the power as well. Now the kicker - on my road bike I could produce approx 300W for the duration, so I'd guess, even if my TT position was pretty uncomfortable (which personally doesn't seem to be the case), I should have put out at least 270W.
From the power models, producing 270W at sea level for 39km/h would solve approx for 0.35 CdA which seems to be quite a high value for a TT bike. For instance, Privateers TT above for his speed and power solves for CdA of 0.28. Too rough of a calculation , do I have the most "unaero" TT position ever
, or something else not taken into account? Will post a pic of me from the finish line of the TT in question later.
Using this modeller http://www.cyclingpowermodels.com/Power ... arios.aspx
(Only disadvantages to this site are the inability to change the pressure and temp figures, which are too favourable for the uk! not many low pressure 20 degree days over here!)
I get privateers to be roughly 0.25-0.24 ignoring elevation changes on the overall power average.
and for yourself assuming 270w we get 0.28-0.29, Room for improvement certainly but that's what this game is about. It takes me weeks of turbo+road training on the TT bike to acclimatise to the position or to positional changes to even come close to replicating my road power on the TT bike.
Maybe try swapping the PM over to the TT bike for some testing?? I have to use my Powertap on box section rim for testing which is a significant compromise over a disc, but the accurate information is essential.
One question, I'm assuming the squared course means it has roughly 4 corners, or is a loop, as slowing to corner and lack of pedalling can have large impacts on the figures too. 8 corners would have a large effect on final results.