Originally Posted by
modernjess
No idea which is faster, and it's not a factor in my decision. Just comes down to personal preference. I'm more comfortable as a rider not wearing the load, which I did for many many years, Now, I commute with a rack and bag. What ever floats your boat.
And that is what it boils down to- personal preference.
I've worn backpack and messenger bag, strapped the backpack to the top of the rack, backpack in a grocery pannier, and used a trunk bag. They all have their pros and cons.
As far as the difference in aerodynamics... I haven't been able to get to wind tunnel to do a controlled experiment.