One thing that seems to pop up on this forum with some regularity is aero bar use. When it comes to aerobars on road bikes there is definitely a good way and a bad way to use aerobars. I'm hoping this can be a quick primer on the good way to go about using aerobars. I will address a caveat at the end for using your road bike more strictly as a TT bike.
So first let me define what I think is good aero bar use is:
- you don't compromise your fit on your road bike
- you are equally aero or more aero in the aero bars than on your drops
- the position is comfortable enough to use for an extended duration
- the position is equally powerful
What I think is the wrong way to use aerobars is: changing your road bike fit to make better use of the aero position, you are no more aero, you are uncomfortable or you lose power.
First, I recommend not moving your seat or your bars. Saddle setback for the purposes of a road bike should be set and stay set. Changing your setback is going to have an ultimate effect on your road bike fit. Same with the bars, if you have a good road bike fit, then smart aerobar choice and setup should allow for a good aero position without screwing up your road bike. Remember, at the end of the day, this is a road bike and having it set up to perform admirably as a road bike should remain its purpose.
Second, choose your aerobar wisely. For most road bike users, you should look for an aerobar that sits very low to the bar. Odds are, that you won't risk being too low. As an example of a "high bar", Richie Porte of Team Sky used a bar with pads about 3-3.5cm above his bar, but he runs a lower bar than most recreational riders (http://velonews.competitor.com/files...te-536x421.jpg) but it still results in a good aero position. The best, modestly priced, aero bar that comes to mind is Ritchey's new pro Sliver. it sits almost literally on top the road bar.
Third, run your extensions short enough that you don't get shoulder pain but long enough that you are allowing yourself to get low(extension length has an impact on body height as well as arm-shoulder angle). Generally, I've found that having your should angle around 100 degrees is pretty comfy on a road bike with clip ons. Bradley Wiggins is on the extreme end of extensions length, here: http://velonews.competitor.com/files...o3-419x421.jpg. Whereas Costa's shorter reach in this picture shows how high up his body is, adding length could bring him down some: http://velonews.competitor.com/files...ta-535x421.jpg.
Caveat: If you are going to use the road bike as a TT specific bike, then I think playing around with saddle setback and bar height is more understandable. Hell, I think that a person who really wants to crush their weekly TT while otherwise using their road bike as a road bike could get down to about a 5 minute conversion process. (The conversion process I'm imagining is having a cheap TT saddle on a spare seatpost set forward and some sort of way to drop your bars(removing spacers or specialized adjustable stem).