Triathlon - Agressive fit and long distance???

I am shopping for a tri bike. I've narrowed it down to four bikes and got to ride 3 today. The last one is being built at my LBS to ride tomorrow. The bike that felt best so far is the QR Kilo in a size 52. I'm 5'11". My back was damn near perfectly flat and I was worried about the bike being small. When riding though it felt great. I was most comfortable and felt most powerful on it. The other two I rode were a 54 Felt S22 and a medium Kuota K-Factor.

I mainly do sprints, an occassional Oly, and plan to try a HIM this fall. I'm a horrible runner though so I will likely be sticking with the sprints and Oly's.

Is this aggressive of a position ok for longer distances? Anyone else do long distance with a really aggressive position? Good idea or bad? Any tips because I'm leaning heavily towards the QR so far.

Thanks for any help.

Oops. Crappy spelling in the title. Can't that be editted?

I have a Felt S25 tri-bike and I ride in a very aggressive position (i.e. very flat back with a big drop from seat to handlebars). I did a 70 miler yesterday and I'd estimate that at least 85-90% of my time was spent in aero position. The only thing that hurts after these long rides is my neck. Having to keep my head up and looking forward is tough for me. If I were doing a full IM, I'd probably opt for a slightly more upright position, but if I can manage it for 70 miles, 56 miles (for a HIM) is doable.

I try to alleviate the sore neck by not lifting my head so high, but it does hamper visibility a little. You may be more flexible in the neck than I am so it might not be an issue for you. For some people, their backs and hamstrings hurt if they ride in an aggressive position for too long, but it hasn't been an issue for me.

Everyone is built a little different so there's really no way to predict how your body will react after a long ride. I'd recommend not cutting your steerer tube until you've done a few really long rides, just to be sure.

I have a related question:

Does the seat tube angle matter when considering the fit of a tri bike? Say two bikes fit you very well, one has a 76 degree, the other a 78.

I have a related question:

Does the seat tube angle matter when considering the fit of a tri bike? Say two bikes fit you very well, one has a 76 degree, the other a 78.Yes. A steeper angle allows a rider to pedal with a more open hip angle. For some riders, this allows them to put more power to the pedals as well as making the bike to run transition easier. But a steep angle doesn't work for everyone. Some people don't like the handling characteristics of a steep seat tube bike. Others say that the steeper position causes more pressure on the pubic/taint area. I prefer 78 degrees, and most professional triathletes ride fairly steep. However, it doesn't work for everyone.

15cm of drop and a reach that would make the UCI upset(around 85cm) and I'm 5'8 or so. I've ridden in a similar position up to 80 miles.

Thanks for the replies everyone. I'm not sure of the drop but will measure it tomorrow when I'm back at the LBS to test ride the P2-SL. The steerer tube is not cut currently but it is at the top, I could go lower if I wanted.

I'm not super flexible but am thin so the position is ok. It felt really good, better than the other bikes I road today. The LBS employee did spend way more time setting it up just for the test ride compared to the other shop and 2 bikes. That may be why it felt so nice. The 55 Kilo was however way too big.

I'll get a measure on the drop tomorrow and see if it changes anyone's opinions.