Little changes in bike fit can make a difference.

Even though I've been pretty happy with the fit of my bike, I was a little disappointed in the (relative) lack of power I've been sustaining in my aero position since I've started measuring it with a power meter. One thing I'd heard mentioned is to keep the upper arms as close to a 90-degree angle to the torso as you can, so I figured I'd give it a shot.

I switched my 100mm stem out for an 80mm stem and took out one 5mm spacer from the steerer tube. My arms are now far enough back that while I'm riding, my knees may occasionally just touch my triceps a couple inches above my elbow.

From my own pseudo-scientific testing on the same course doing intervals at threshold, I was able to increase my average power output at LT HR by 15-20 watts. Just subjectively, bringing my elbows back as far as they'd go makes me feel more compact and somehow able to deliver more power to the pedals. The position just FEELS stronger.

I love the aerodynamic goodies as much as the next guy, but that kind of power increase is nothing to sneeze at, and all it took was a $40 stem and a few minutes of wrenching...