Originally Posted by
Triguy
but when your seat is around 78-82 degrees, it is significantly higher(1+cm) than if it were around 76.
No, it's not. The difference in seat height when you move 2 degrees forward is very small (less than 1/4cm), assuming that the distance between the pedals and your measuring point on your saddle stays constant. Do the geometry for yourself.
This means that as a whole your body is sitting higher in the air, meaning a flat backed steep position is often less aerodynamic than a slightly rounded more slack position.
Do you have aero data to prove this?
Check out the FA positions on biketechreview.com.
Frontal Area isn't everything. There are many, many more considerations than just frontal area alone. For example, the angle of your arms with respect to vertical.
Secondly, having more weight on your front end often requires wider arms and shoulders.
This is not true, not even "often". The weight distribution on the front end and the width of the aerobar pads are independent variables.
Long ago Lances aero gurus agreed that getting narrow had big gains with less negatives on power and comfort than getting low.
This N=1 example is not a good one, because Lance had a back problem that prevented him from getting very low. All the gurus who have done scientific studies agree that for most triathletes, the solution is to get as low as you can (comfortably), then as narrow as you can (comfortably). I don't have a source off the top of my head for this contention, but I'll find one if you want.
For an N=1 perspective, I brought my seat back 4cm and down accordingly, my power files suggest no change in aerodynamics
Of course your power files won't show (or even suggest) any change in aerodynamics! Your power meter doesn't measure aerodynamics! Admittedly, one puts out less power in a more forward aero position, but the aerodynamic gains more than make up for it.
but my crotch neck and power files sure thank me.
The fact that your crotch and neck hurt when you move forward suggests an improper fit, not any inherent flaw in a forward position.
I don't think Steep or slack is right or wrong. It's an individual choice.
I think riding steep is right, and riding slack is wrong. It is a choice, but if you ride slack you may be making the wrong choice. I have scientific evidence to support this contention. Unless you can provide scientific evidence that supports riding at 76 degrees over riding at 78 degrees, we'll have to agree to disagree.
Source:
http://www.slowtwitch.com/Tech/What_...ngles_222.html