The pros bring the knees what appear to be up and close if not over the frame while pedaling.

Is there more power output?

Is it the preferred pedal stroke? Is this taught some where?

Isn't keeping everything in line (knees, feet) easier on the knees than trying to bend the knees sideways at the top of the stroke?

I could see some advantage in a ITT.. but for all other ??

well, if u see an advantage in an ITT, then you'll see an advantage everywhere.....

i have no idea about the biometrics of it all, but i've always kept my knees in, not just because i was trying to, and never had any problems with it.

The pros bring the knees what appear to be up and close if not over the frame while pedaling.

Is there more power output?

Is it the preferred pedal stroke? Is this taught some where?

Isn't keeping everything in line (knees, feet) easier on the knees than trying to bend the knees sideways at the top of the stroke?

I could see some advantage in a ITT.. but for all other ??

Keep everything in line. There are no advantages of bringing your knee in Aero or otherwise. Keeping everything in line produces the best power output.

Straight up and down is pretty good -- Arnie Baker et al describe some people having knee problems TRYING to pedal knees-in.

I think with the pros, they are using the lowest Q-factor choice of pedals and crank available, and tend to run a very high saddle height. Many amateurs have their knees too far apart from too low a saddle height.

My knees almost barely brush the top tube when I pedal, just naturally, when properly adjusted, with a campy double crank and speedplays.

Straight up and down is pretty good -- Arnie Baker et al describe some people having knee problems TRYING to pedal knees-in.

I think with the pros, they are using the lowest Q-factor choice of pedals and crank available, and tend to run a very high saddle height. Many amateurs have their knees too far apart from too low a saddle height.

My knees almost barely brush the top tube when I pedal, just naturally, when properly adjusted, with a campy double crank and speedplays.

The keeping everything in line comment is straight from the bio mechnical suggestion of a wobble naught fit, so we'er not going from a to low saddle (which usually makes people pedal knee out). I use to let me knees come in a brush my top tube but have worked to correct this problem. That said I doubt one would be causing any damage or major power loss unless your feeling pain as well your not going to see any benefits in aerodynamics.