Recently, I was wondering why the fastest time trial times over standard distances really aren't all that much faster in today's aero age than when they were twenty years ago, before the advent of aerobars, disk wheels, and sculpted carbon framesets. For instance, in 1978, British rider Alf Engers rode a 49.24 twenty-five mile time trial on a stock road bike, and in 1988, Colin Sturgess rode a ten mile time trial to a startling 18.48. While there are, of course, outlying performances such as Chris Boardman's 45.57 twenty-five mile ride and Bradley Wiggins' 17.57 ten miler, there is not a significant difference in times for the most of the fastest riders, whether or not their performances took place after the advent of high tech aerodynamic bicycle technologies. Interesting, a similar pattern emerges when examining the bike splits at Kona, too.
So the question naturally arises as to whether developments such as aerobars and disk wheels make a significant difference for most elite riders. It's generally accepted that a low position on the bike--pelvis rotated forward, elbows in, head held below the level of the shoulders--is necessary to go fast.
Note in the photo above, the rider's back is flat and his head is held low. By rotating his pelvis forward, he is able to further drop his shoulders to achieve a more optimal aerodynamic position.
The rider in this photo has his pelvis in a more neutral position, which forces his shoulders up; this also causes him to stretch in his reach for his aerobars (notice that the angle of his elbows is much greater than ninety degrees).
A quick review of the top time trialists of the seventies and early eighties demonstrate positions remarkably similar to those achieved today with aerobars.
The riders in the photos above all have extremely aerodynamic positions, probably better than most riders today who use aerobars. Their backs are flat, their heads are low, their arms are held tight to their bodies, and their pelvis' are rotated forward to further drop their shoulders.
Would these riders have been faster with aerobars? Most likely, but not for the reason that you might think. It is possible to achieve a very efficient aerodynamic position without the use of aerobars, provided that you have a strong core, exceptional concentration, and a willingness to suffer greatly during your ride. What aerobars do for most riders to to enable them to achieve a good aerodynamic position with reduced physical effort--aerobars enable the arms and shoulders to support their upper body, which allows more energy and attention to be directed toward making the bike move forward quickly. What I am suggesting is that it is very possible to have an extremely effective body position without aerobars for a shorter (say, less than ten miles) time trial. (Example: hands held near the stem on bar tops, back flat/slightly below horizontal, elbows held tightly against the body, etc.); Of course, holding such a position without aerobars would require exceptionally strong core strength.
Do aerobars and the latest in tricked out aero wheels and bicycle frames make a difference? According to most studies, aerodynamic bicycle equipment can yield up at a 10% gain in performance, which is huge for most riders. But more important than aerodynamic equipment is making sure that you are fitted properly to your bike and that your body position is optimized for power and aerodynamics as much as possible. Unless these two criteria are met, no aerobar or expensive time trial equipment will make you appreciably faster.