Which one produces lesser friction?
or #2 )http://ecx.images-amazon.com/images/...aL._SY300_.jpg
As you can see, both options are quite bulging. I do feel, however, that the first option is more aerodynamic. It would be completely blocked by my butt and back. On the other hand, side panniers are only partially blocked by my legs. I still need to make sure: has there been any experiment to show any aerodynamic differences?