I have exactly the same problem!I had a little go yesterday, although I do have drops I don't often try to assume the nearest I can get to a full TT position, but feeling the spirit of the TDF I thought why not. Tried to keep the same amount of effort and pushed up from about 23mph to 23.7mphish (it wasn't much of a headwind in fairness) then got a bit fed up of my thighs hitting my gut so sat back up again.
I had a little go yesterday, although I do have drops I don't often try to assume the nearest I can get to a full TT position, but feeling the spirit of the TDF I thought why not. Tried to keep the same amount of effort and pushed up from about 23mph to 23.7mphish (it wasn't much of a headwind in fairness) then got a bit fed up of my thighs hitting my gut so sat back up again.
I have exactly the same problem!
When I was slim, I used the drops a lot more because the position was much more comfortable for me than it is now. Nowadays, it is only for use on downhills and into killer headwinds.