Here is an interesting pic of @
Racer Ex and @
Cleave in a race. One can guess who is passing whom in this pic but to be fair, I have been passed by R Ex in a 2k pursuit in Carson. So the passed by R Ex club is very elite.
This pic offers a chance to compare and contrast the two riders but not to criticize but observe and learn what may work for the individual.
I have somewhat poor neck flexibility. I cannot look up the way R Ex does in the pic. So if I use a lower position, my forward visibility is not great. I did the aero testing at Velo Sports Center and a Retul fit, so I have the optimized position for best aerodynamics and fit.
I can ride the ERO position but I my up road visibility is not great. So I tend to train in a higher position so I can see the traffic and etc ahead. The same is true on the track if there are other racers using the track.
Also, if one brings their arms together, it may cause the head to pop up. Head position is probably the greatest impact on CdA so gains by having the arms together may be offset by the head coming up.
So being able to turtle ones head while having the arms close together may result in a lower CdA.
Control is another major factor in determining speed. The bike goes the fastest when it is going straight and not turning. At the track, slight changes in position in the pole lane scrubs speed. And at VSC, this is even more apparent due to the short radius turns. So if one can keep the arms together, turtle ones head and ride the turns in a constant radius turn, you are there.
Crank length is another interesting discussion. ERO told me that team New Zealand showed up for testing with 155 mm cranks. The only way to know which is faster is to test.
I have found that shorter cranks allow me to stay on top of the gear better. Also, since I have been sprint training, I find I produce more power and spin faster in the ERO position on my pursuit bike than riding on the hoods of my road bike. Likewise if I ride my road bike and do a lot of climbing I will not do well in the ERO position at high cadence on my pursuit bike.