Originally Posted by
Moisture
How are the aerodynamics so affected?
Read the thread. Read 531Aussie's posts.
Simply, its because as the cranks get longer, your knees rise higher into your chest at the top of the stroke, so you can't breath as well to start with and eventually your knees hitting your chest prevents a low back position being held at all, thereby making you less aerodynamic. Any gain in power is lost to extra wind resistance.